DES 40A – 001
March 13, 2014
The Materials in a Coil Mattress
Every year in the United States, around 40 million mattresses are sold (Mattress Stewardship Briefing Document). Mattresses play an important role in our daily lives. In today’s society, we care a lot about comfort but we do not pay enough attention to the materials in a product that may directly affect our health. Although people frequently emphasize the importance of comfort, for a piece of furniture that we sleep on every night, it is essential to know what substances it may contain, because some materials include toxic chemicals. It is also valuable to understand the manufacturing process and acknowledge what happens when we dispose of these possibly toxic mattresses. As my group and I began to consider possible topics, we started by choosing futons but we quickly came to realize that the topic was too broad. Next, we decided to look into futon mattresses. However, this topic was too specific and did not have enough information. Ultimately, we chose to investigate mattresses. There are two main types of mattresses: coil and non-coil. After gathering enough research, we narrowed our topic to coil mattresses.
A mattress typically consists of three layers, the center/springs, then the supporting layer, followed by a quilt layer. For the center of a spring mattress, there are several options of coils. There are Bonnell/open coils, offset coils, continuous coils, and pocket coils. The coil examined throughout this paper is the pocket coil, which is made of steel wires and is shown in Figure 1. Steel is a secondary raw material. The primary raw materials used to form steel are coal, limestone, and iron ore (Steel and raw materials).
A support layer follows the center coil section. Comfort layers can consist of various materials such as latex, polyurethane foam, viscoelastic foam (a type of polyurethane foam), and cotton batting. There are two main kinds of natural latex, Dunlop and Talalay. The raw latex is collected from rubber trees. The difference between the two natural types is the way they are manufactured (Mattress Information). A third common type of latex is the synthetic latex. Another material found in a mattress is polyurethane (PU), which is a type of both rigid and flexible foam. “The chemical nature of the PU, the high air permeability, and the high inner surface area of the foam structure cause this material to be highly flammable” (Konig, A., et al., 469). Since polyurethane foam is highly flammable, it is required to have a fire retardant. A fire resistant material is used on mattresses in the United States because it is a required law. A natural substance that is commonly used is melamine, which is mixed with formaldehyde to create a melamine resin (the fire retardant). Formaldehyde can be absorbed by inhaling and/or through our skin. This chemical can have both minor and serious effects on human health.
Symptoms of low-level exposure include; runny nose, sore throat, cough, dermatitis, sleeping difficulties, headache, fatigue, breathing difficulties, sinus irritation, chest pain, frequent nausea, bronchitis, and decreased lung capacity. Signs of acute exposure include; abdominal pain, anxiety, coma, convulsions, diarrhea, and respiratory problems such as bronchitis, pneumonia or pulmonary edema (Healthy Home Test Kits).
Even when there is, only a small amount of formaldehyde on a mattress it can still take years for the chemical to disappear. Chemicals typically found in fire retardants are boric acid and antimony. Moreover, the fire retardant used the most right now for flexible polyurethane foam is tris (chloropropyl) phosphate or deca-BDE (decabromdiphenylether) (Konig, A., et al., 470). These chemicals incorporated into fire retardants can be highly toxic and no one really wants to sleep, night after night, on dangerous materials. Something to consider as an alternative for toxic fire retardants would be wool, which naturally acts as a fire barrier. Wool can be found in some mattresses, this material could be used as a more permanent solution for a fire retardant.
According to the article “Examining Viscoelastic Flexible Polyurethane Foam,” viscoelastic foam is a kind of flexible polyurethane foam. Any further information, regarding the primary raw materials used to construct this foam, appears unavailable. The materials used in the viscoelastic foam maybe made of similar materials to the polyurethane foam since it is a type of polyurethane foam. “Although viscoelastic foam production technology has been available for more than 35 years, commercial products have only recently been made widely available to consumers” (Mattress Information). This may be a result of the product being newer; therefore, there is a lack of information provided. A fourth substance used in a support layer is cotton batting, which is a primary raw material. Cotton can contain harmful chemicals that are used for pesticides to help the crops grow.
The final outer layer is the quilt/top layer. This layer can consist of different substances; this paper will concentrate on polyester fabric. Polyester fibers “are long chain polymers derived from coal, air, water, and petroleum,” which develop during chemical reactions amongst an acid and alcohol (Polyester Manufacturing). There are two types of polyester, PET (the most common) and PCDT. The main raw material in PET polyester is ethylene derived from petroleum. “It is oxidized to produce a glycol monomer dihydric alcohol which is further combined with another monomer, terephthalic acid at a high temperature in a vacuum. Polymerization, the chemical process that produces the finished polyester, is done with the help of catalysts” (Polyester Manufacturing).
Mattress construction involves several steps along the way. Once the size of the bed is decided, manufacturers begin by constructing the center pocket springs. The coils acquire their unique shape from tempering steel with heat or electricity. The electricity used in the production is a secondary raw material, which comes from coal – a primary raw material. These steel coils are individually enclosed in a pocket of fabric, linking them to adjacent coil-casing groups (Pepper). The number of coils in a mattress will vary depending on the size of the bed and the gauge/thickness of the wire. According to “Innerspring Mattress Information,” the higher quality mattresses generally have a 13-gauge wire (Whitney). The author also points out that the higher gauged numbers are thinner wires. Moreover, to delay the process of corrosion some manufactures will add a plastic coating or enamel to the springs (Whitney). A majority of companies will have other specialized manufacturers construct the center springs. According to Pepper, after springs are fabricated and the mattress company acquires them, the workers will inspect the work. Then, the manufacturers will sew a fabric around the coils as an insulator, preventing the following layer from molding or being caught in the coils (Manufacturing Process of Mattress).
Next, in a mattress is the support layer, which determines the comfort level. In this section, there can be several layers of cushiony material depending on the company and the type of mattress. The materials that are used, are placed on both sides of the center, building the mattress outwards. As previously discussed, this mattress portion can consist of latex, polyurethane, viscoelastic, and cotton batting. This section can typically range from two to eight layers, while the thickness can range around one fourth of an inch to two inches (Manufacturing Process of Mattress). The final layer, commonly known as the quilt layer, provides a functional purpose along with a beautiful design. As noted above, this layer can consist of polyester fabric. To produce this layer, manufacturers generally use a giant quilting machine. The machine usually has a range of different needles to stitch the cover to a portion of backing material (Pepper). Stitching the mattress helps to avoid it from moving across the support layers. “Once the fabric is quilted, it is cut into panels that will fit the top and bottom of the mattress” (Pepper). The side portions of the mattress are taken from the material used for the top and bottom or designed individually on a border machine. Before adding the side panels to the mattress, any vents or handles have to be attached.
Once the three mattress layers are constructed, workers attach flanges. “Flanges are the connecting panels that are attached to the quilted cover of the mattress with the help of hog rings which are large, round staples. The flanges are attached to the top and bottom panels with the help of a specially modified sewing machine and the hogs rings are stapled to the flanges. During the closing operation, the hogs rings are secured to the innerspring unit” (Manufacturing Process of Mattress). After attaching the flanges, the most critical part of the mattress manufacturing takes place, the closing operation. According to Pepper, this process requires a movable sewing head that is located on a track. To accomplish this closing task “tape edge operators manually feed the top, bottom, and side panels and a heavy duty binding tape into the sewing machine as it moves around the mattress” (Pepper). It is crucial for the operators to know how much material to feed into the machine. Pepper states that, the final product will portray the tailor’s professional expertise.
Once constructed and fully inspected, a mattress is sent to the packaging area. The first step in this area is to attach the warning label along with the care directions. Next, the mattress is packaged in a plastic or a paper cover, either by hand or by a machine. Mattresses can be sealed in bags or films, which are typically clear, made from flexible polyethylene. For additional protection, a boot film can be added. A boot film of red, blue, or black can be incorporated through an automated wrapper. Once a mattress is packaged and sealed up tight, it is ready for transportation. Throughout the life cycle of a mattress, these pieces of furniture are commonly transported by trucks. For extra support, some transportation vehicles will “line the beds with new or scrap corrugated cardboard” (Nelles).
In the article “Box Spring Mattress Fact Sheet,” Lisa Sefcik states, mattresses can last between five to seven years. A person can tell a mattress needs replacing by the feel and the appearance. If the mattress looks as though it is sagging, it may be time to replace it. It is important to constantly rotate and flip a spring mattress to help lengthen the lifespan. Sefcik explains how a newer mattress needs rotating every two weeks for a few months and afterwards it can be rotated every couple of months. She also acknowledges that in between rotations, the mattress needs to be flipped. During the lifecycle of a mattress, repairs can be made in order to be reused. According to the Consumer Product Safety Commission discussed in the “Mattress Stewardship Briefing Document” batting can be replaced, mattresses can be stripped down to the springs (as seen in Figure 2) and rebuilt, and various elements can be replaced with new or recycled materials.
Although renovations can be made, people generally tend to dispose of their old mattress to buy a brand new one. When people discard their mattresses two things can occur; the mattress or mattress parts can be recycled or the mattress can be sent directly to the dump. When mattresses are recycled, they are stripped down and their components are separated into different groups. “Mattress Stewardship Briefing Document” provides a chart explaining what certain materials can be recycled and into what products. The chart shows that the steels coils can be reused as scrap metal, while the polyurethane foam, cotton and other similar fibers can be incorporated into carpet underlay.
Meanwhile, “of the 40 million new mattresses and box springs sold every year, only a small percentage of the used mattresses they replace are recycled.” In other words, the majority of these mattresses are being tossed into dumps (as seen in Figure 3). When people dispose of mattresses at a landfill, there is generally a “Landfill tipping fee” as the “Mattress Stewardship Briefing Document” calls it. These fees are based on the weight of the product. These fees can also results in illegal dumping because people are not willing to pay to dispose of their old mattress. Bulky, yet flexible mattresses can also cause problems when trying to compact and bury them in dumps. Another common issue found in landfills is with the steel springs. These coils can destroy equipment that is typically used to compact and shred products, therefore, certain facilities will require mattresses to be removed from the solid waste group. (Mattress Stewardship Briefing Document).
Mattresses are an important part of our lives; therefore, when purchasing a mattress we should investigate both the level of comfort and the materials inside. People sleep on their mattress without even knowing that what is beneath them can contain toxic chemicals. People need to understand the steps of a mattress’ lifecycle and contemplate the possible outcomes of disposal methods. With all of this knowledge, people can make better-educated decisions when they are dealing with mattresses.
“ALL ABOUT MATTRESS COILS.” All About Mattress Coils. Sit 'n Sleep, n.d. Web. 07 Feb. 2014. <https://www.sitnsleep.com/resources/article/all-about-mattress-coils>.
Double Pocket Spring Mattress. Digital image. Forcom: For Comfortable Mattress. Festure, n.d. Web. 15 Feb. 2014 <http://img.weiku.com/a/015/966/Luxury_Plush_39cm_15_quot_individually_coil_mattress_double_pocket_spring_9407_3.jpg>.
“Examining Viscoelastic Flexible Polyurethane Foam.” IN TOUCH, June 2003. Web. 8 Mar. 2014. <http://www.pfa.org/intouch/pdf/IntouchV11_1_read.pdf>.
Griffiths, Tony, Charles Coe, Fabio Fiori, and Ian Berry. “Mattress Recycling.” Waste and Resource Management 166.4 (2013): 158-66. ICE, Nov. 2013. Web. 5 Mar. 2014. <https://vpn.lib.ucdavis.edu/,DanaInfo=ucelinks.cdlib.org,Port=8888+sfx_local?sid=EI:Compendex&genre=article&issn=1747-6526&date=2013&volume=166&issue=4&spage=158&epage=166&title=Proceedings+of+Institution+of+Civil+Engineers%3A+Waste+and+Resource+Management&atitle=Mattress+recycling&aulast=Griffiths&aufirst=Tony&isbn=> .
Hartman, Eviana. "Mattress Eco-Matters: Don't Take It Lying Down." Washington Post. The Washington Post, 06 Apr. 2008. Web. 07 Feb. 2014. <http://www.washingtonpost.com/wp-dyn/content/article/2008/04/03/AR2008040303081.html>.
"Healthy Home Test Kits." Formaldehyde Facts. N.p., n.d. Web. 11 Mar. 2014. <http://prohousedr.com/formfact.htm>.
“How Springs Are Made.” How Springs Are Made. ThomasNet, 7 Mar. 2014. Web. 07 Mar. 2014. <http://www.thomasnet.com/articles/machinery-tools-supplies/how-are-springs-made>.
“Innerspring/Coil Mattresses.” Inner Spring Coil Mattresses. Mattress Mattress Inc., n.d. Web. 15 Feb. 2014. <http://mattressmattress.com/coil-mattresses.html>.
Konig, A., et al. “Flexible Polyurethane Foam with the Flame-retardant Melamine.” Cellular Plastics 44.6 (2008): 469-80. Sage. Web. 5 Mar. 2014 <https://vpn.lib.ucdavis.edu/content/44/6/,DanaInfo=cel.sagepub.com+469.full.pdf+html>.
Lanoe, Thomas, Carla L. Simoes, and Ricardo Simoes. “Improving the Environmental Performance of Bedding Products by Using Life Cycle Assessment at the Design Stage.” Cleaner Production 52 (2013): 155-64. ScienceDirect. Elsevier, 21 Mar. 2013. Web. 05 Mar. 2014. <https://vpn.lib.ucdavis.edu/science/article/pii/%2CDanaInfo%3Dwww.sciencedirect.com%2BS0959652613001479>.
“Manufacturing Process of Mattress.” Manufacturing Process of Mattress. Textile Exchange, n.d. Web. 07 Feb. 2014. <http://www.teonline.com/knowledge-centre/manufacturing-process-mattress.html>.
Mast Business Directory. “Factors That Need Consideration While Starting Manufacturing for Beds and Mattresses.” Mast Business Directory. Mastbusiness.com, n.d. Web. 07 Feb. 2014. <http://www.mastbusiness.com/bizarticles/ba465/>.
“Mattress Construction.” Mattress Information//Mattress Upholstery and Foam Beds. N.p., n.d. Web. 07 Feb. 2014. <http://matresses101guide.com/Mattress_Construction_Mattress_Upholstery_and_foam_beds.html>.
“Mattress Information/Mattress Construction/Mattress Springs or Mattress Coil.” Mattress Information/Mattress Construction/Mattress Springs or Mattress Coil. N.p., n.d. Web. 07 Feb. 2014. <http://matresses101guide.com/Mattress_Construction_Mattress_Springs_or_Mattress_Coil.html>.
Mattress Layers. Digital image. Mattress5.jpg. N.p., n.d. Web. 15 Feb. 2014. <http://i889.photobucket.com/albums/ac95/timeless-design/2012bed/mattress5.jpg>.
Mattress Production Process of Akant Ltd. YouTube. YouTube, 5 May 2009. Web. 3 Mar. 2014. <http://www.youtube.com/watch?v=_V7XdiAAULU>.
“Mattress Stewardship Briefing Document.” Product Stewardship Institute, Inc. | Mattress Stewardship Briefing Document. Product Stewardship Institute, Inc., 25 July 2011. Web. 7 Feb. 2014. <http://www.productstewardship.us/associations/6596/files/Mattress_Stewardship_Briefing_Document_FINAL.pdf>
“Mattress and Box Spring Case Study: The Potential Impacts of Extended Producer Responsibility in California on Global Greenhouse Gas (GHG) Emissions.” Mattress and Box Spring Case Study: The Potential Impacts of Extended Producer Responsibility in California on Global Greenhouse Gas (GHG) Emissions. California Department of Resources Recycling and Recovery (CalRecycle), 20 Nov. 2012. Web. 07 Feb. 2014. <http://www.calrecycle.ca.gov/publications/Documents/1430%5C20121430.pdf>.
“Mattress Buyers Guide to Off Gasing.” Articlesbase.com. Articlesbase.com, 17 Dec. 2008. Web. 07 Feb. 2014. <http://www.articlesbase.com/sleep-articles/mattress-buyers-guide-to-off-gassing-688552.html>.
McMahhon, Mary. “What Is Melamine?” WiseGEEK. WiseGEEK, 10 Feb. 2014. Web. 08 Mar. 2014. <http://www.wisegeek.org/what-is-melamine.htm>.
Nelles, Barbara. “Mattress Packaging Equipment to Keep Beds Clean, Costs down.” BedTimes. BedTimes, Mar. 2009. Web. 10 Mar. 2014. <http://bedtimesmagazine.com/2009/03/mattress-packaging-equipment-to-keep-beds-clean-costs-down/>.
“Pepper, Dan. "How Products Are Made-Mattress.” How Mattress Is Made. Advameg, Inc., n.d. Web. 07 Feb. 2014. <http://www.madehow.com/Volume-1/Mattress.html>.
“Polyester Manufacturing.” Types Of Polyester & Polyester Yarn With Its Manufacturing Process & Application. Textile Exchange, n.d. Web. 08 Mar. 2014. <http://www.teonline.com/knowledge-centre/polyester-manufacturing.html>.
Sefcik, Lisa. “Box Spring Mattress Fact Sheet.” Overstock.com: Online Shopping. Overstock.com, n.d. Web. 07 Feb. 2014. <http://www.overstock.com/guides/box-spring-mattress-fact-sheet>.
Sleeping in Style. Digital image. Explanation-of-layers.jpg. N.p., n.d. Web. 15 Feb. 2014. <http://cbsminnesota.files.wordpress.com/2012/08/explanation-of-layers.jpg>.
“Steel and raw materials.” Fact Sheet Raw Materials - World Steel Association. World Steel, May 2011. Web. 7 Mar. 2014. <http://www.worldsteel.org/dms/internetDocumentList/fact-sheets/Fact-sheet_Raw-materials2011/document/Fact%20sheet_Raw%20materials2011.pdf>.
Watson, Catie. “What Is Polyester Fabric Made From?” EHow. Demand Media, 22 Dec. 2009. Web. 08 Mar. 2014. <http://www.ehow.com/facts_5792204_polyester-fabric-made-from_.html>.
Whitney, Nicole. “Innerspring Mattress Information.” Innerspring Mattress Information | EHow. Demand Media, 25 June 2010. Web. 07 Feb. 2014. <http://www.ehow.com/about_6657734_innerspring-mattress-information.html>.
Willis, John. “Stages of the Cotton Manufacturing Process.” EHow. Demand Media, 06 June 2011. Web. 11 Mar. 2014.
DESIGN 40A W/14
Embodied Energy of a Spring Mattress
Sleeping is something we do on a regular basis. We depend on our mattress to provide us with comfort in order to get a good night rest. We spend almost half our life sleeping, but unless that mattress is sagging or it doesn’t properly support us anymore do we have any thoughts about it. Sleep is one of our most routine tasks, and lets be honest, it’s one of the best routines we have. With mattress production, the goal is less oriented on sustainability, and more focused on sales/monetary gain. The energy spent for the purpose our restful sleep should be enough for us to lose a few hours. My group decided to study and research the lifecycle of a pocket spring mattress in order to gain some knowledge and enlightenment about what a product goes through from cradle to grave (or cradle to cradle). I have been given the task of writing about embodied energy, which appears to be the connection between both materials as well as waste throughout the life of this given product. I will explain the information I found regarding the embodied energy in the production process of obtaining the very mattresses we sleep on.
Extraction and refinement as well as shipping of materials are the most costly, and energy intensive processes in the creation of a mattress. In Mattress and Box Spring Study, the energy breakdown in the production process is discussed. They state “the production of goods from…[mattress manufacturing] measured in 2002 producer price has cradle-to-gate greenhouse gas emissions of 129 kg of CO2E and energy requirements of 1,745 MJ.” Their statement of “cradle-to-gate” refers to “all upstream economic activities, from drilling and mining, shipping, beneficiation and processing, including the actual manufacturing of the product.” This process measured roughly 12 years ago consumed 484.72 kWh of energy from extraction, transportation, and production. As demand for mattresses hasn’t changed much, it can be deduced that the statistic is still relevant, however as technology improves, energy consumption increases (in the case of automated or automatic machines). The study continues to break down the five most energy intensive portions that lead to the main amount of energy consumption by means of fossil fuel. The first and most energy intensive are Power Generation and Supply, which uses 449 MJ of energy. Second highest fuel consumption is 173.1 MJ and is used in the process of drilling, extracting and refining of Iron and Steel. Next is “Other Basic Organic chemical manufacturing” which includes materials such as latex, cotton, polyurethane etc. and uses 129.2 MJ. Trucks and transportation create the next highest energy use at 80.1 MJ. Lastly, Oil and Gas Extraction are the next largest consumers of energy using 25.8MJ of energy. The vast majority of the energy consumed during extraction, refinement and transportation is consumed by oil and gas, making the five most energy intensive portions (making up nearly 50 percent of the total energy use per mattress) heavily reliant on fossil fuels.
Upon looking for information about the energy used during the production process, I found that there are at least eight major machines (and possibly more for “high end” mattresses) required to create a pocket spring mattress. I found information about energy use of these machines on the website of a Chinese mattress machine manufacture called Xidengbao. This company provided information about each machine and their particular purpose as well as energy consumption by each machine. I will continue to explain these machines produced by Xidengbao in the following “production” paragraphs. In order to best represent the current times I chose the machines (typically the newest) to best represent the industry standard for mattress production.
The innermost structure of a mattress is the springs or coils. There are various types of coils used in mattresses, however to simplify the research my group chose to look into pocket springs. Pocket springs are made by a machine that coil and slice steel rods of different thickness into springs that are then dropped into pockets of fabric that are either stitched or glued closed. These pockets are connected as a single sheet of pockets that have one spring per pocket. A high-speed pocket spring machine is responsible for the process of cutting steel and encasing/closing the pockets. According to Xidengbao, the LR-PS-HX2/HF2 High Speed Pocket spring machine uses approximately 18 kilowatts of energy. As with every other machine used in the production process involved in making a mattress, the energy is derived from electricity.
The second part of the process is where the sheets of pocket springs are glued together to form a solid sheet of coils in the shape of any size mattress that is desired. The strip of pocket springs is fed into an automated machine that folds the sheets back and forth while gluing them together in order to create the mattress shape. Because there is less involved in the process of stacking and gluing the pockets together, this machine uses considerably less energy than the previous. Xidengbao’s machine, the LR-PSA-95P Fully Automatic Pocket spring assembly machine uses 8kW of energy.
The third step in the manufacture process is the creation of the foam layers. This is by far the most energy-demanding portion of the production process. A machine creates layers of polyurethane or latex foam by atomizing (breaking polyurethane into small particles) and spraying the foam in different levels of density. The foam is sent out as a solid unit that will later need to be cut to size and thickness to properly fit each mattress. Depending on the mattress, it is possible to have 2 separate machines for different types of foam. Xidengbao’s XLF-2400 automatic horizontal continuous foaming production line machine uses 130 kilowatts of energy to produce the foam. This stage is responsible for 74.2% of the overall energy consumption during the production process.
After creating the foam, the next step is to cut it down from a block to form the correct size to fit in a mattress. The XPQ-1650/2150 horizontal foam cutting machine by Xidengbao feeds the foam block through and is directed by a computer program to make exact cuts for the mattress padded layer. The entire process of cutting down and splitting the foam uses 8.32 kilowatts of electrical energy.
The outer layer of a mattress has a quilted top. This layer consists of two layers of fabric with an inner layer of cotton batting. These layers are sent through a machine where a computer driven system uses an industrial type sewing machine to create a desired quilted pattern. Material density and complexity of pattern can alter the power output used from this machine, however, the HF-DZ-1 High Speed Computerized Single Needle Quilting Machine (Xidengbao) uses approximately 8.8 kilowatts of electrical energy.
After all the separate parts of the mattress are created, cut, constructed or built, the next stage in the production process is assembly. Workers place the materials of the mattress together, making sure to have the same materials on either side. This includes the quilted top and bottom, layers of foam, and pocket springs. Once assembled, they use a tool called a WB-3C Highlift Tape Edge Machine (Xidengbao) which creates the outer edge of the mattress. This edge sometimes has handles, but often has a similar quilted pattern as the top and bottom. The machine uses only 1.5 kilowatts of energy to create the “edge tape”, where a worker then installs it. The final step in the construction of a mattress is where the top and “taped” edge are sewn together to fully encase the inside materials. This last stage in the production process is done by a WY-2A Mattress Border Tape Sewing Machine and uses the least amount of energy in the entire process at a mere .58 kilowatts of energy. The production process is complete once all the edges are sewn closed.
The total embodied energy for the use of one set of machines in the production process is 175.2 kilowatts (630.72 MJ), which is entirely derived solely from electrical power. With large industry operators such as Tempur Sealy International, who own 270.8 million dollars worth of equipment (statistics from Form K-10 Annual Report Tempur Sealy International, inc.), it can be assumed that their electrical energy consumption is much higher than the one I projected, because it is likely they own and operate more than one set of machines per factory. Not to mention, the energy costs generated for use of machinery accounts only for machines used for creating the mattress itself. It does not include other utilities such as lights, cooling/heating, employee commute or shipment of materials.
All the machines used for creating the mattress itself during the production process use electrical energy for power. The actual production of a mattress harnesses the most electric energy while all of the other components (especially extraction and transportation) use fossil fuel. Tempur Sealy International reported purchasing 62.5 million dollars worth of raw materials. Their operational expenses in the past year reached 771.1 million dollars (statistics from Form K-10 Annual Report Tempur Sealy International, inc.). This cost includes electricity, transportation, shipping, and other various items such as utilities and raw materials for one of the largest mattress manufactures in the USA.
There are several different components that attribute to transportation, and they tend to happen between each step in producing a mattress. As with the majority of products sold in the US, many of them are imported. “Around 3 million of 38 million mattresses and box springs sold in the U.S. in 2010 were imports” (Mattress and Box Spring Study). With each imported mattress, there is an added cost for fuel, and aside from cost, we are contributing to extra use of fossil fuels for a slightly cheaper product (labor is cheaper outside the US). According to Mattress and Box Spring Study, there are “38 million mattresses and box springs were sold in the U.S. in 2010”. This would have a direct correlation to shipping and therefore fuel consumption. Transportation happens between each step of the process. When materials are extracted, they are then shipped to mills where they are refined. After they are refined they are then shipped to the mattress manufacture. After a mattress is fully assembled, it is then shipped to a warehouse or sales floor. After it is sold, the new mattress is driven or shipped to the residence of the new mattress owner. Either dumping or recycling discards the old mattress, but regardless the outcome, the mattress is then shipped yet again. Transportation to a recycling center alone is explained when Mattress and Box Spring Study states, “three quarters of the collected end-of-life mattresses and box springs are first driven to a transfer station or other nearby collection site in a private vehicle, and the maximum length of a round-trip to collect each mattress and box spring set in a combination truck is 320km (200 miles)… Together with energy and greenhouse gas data for light duty vehicles and combination trucks, this results in primary energy demand for reverse logistics of around 60 MJ and cradle-to-gate greenhouse gas emissions of roughly 4 kg CO2E per mattress and box spring set.” “Dumping the mattress in a landfill uses 52.4MJ of energy in transportation” (Mattress and Box Spring Study).
The last and final stage of a mattress is disposal. Although we hardly think about what happens to our junk when we dispose of it, but the process of disposal is somewhat energy intensive as well. There are three major disposals of mattresses. The first and “greenest” way is recycling, because 85% of a mattress is recyclable (Mattress and Box Spring Study). “Primary energy demand and greenhouse gas emissions come from the transportation of the mattress and box spring from their pickup location to the landfill, as well as the construction, maintenance, and operation of the landfill itself… An estimated 69.3 MJ and 8.3 kg CO2E are avoided whenever an entire set is reused instead of landfilled” (Mattress and Box Spring Study). Although the “ideal” method of disposal is recycling, the vast majority of mattresses end up in the dump anyways. Due to manual processing (as opposed to automatic or machine processing) in the disassembly of a mattress, “the energy demand and greenhouse gas emissions from mattress and box spring reprocessing are minimal… Energy consumption data from the largest mattress recycling facility in the U.S. results in 8 MJ of primary energy per mattress and box spring set...” (Mattress and Box Spring Study). A little over half of the recycling energy is derived from oil and gasoline use for basic machines, while the remainder is derived from electricity.
The total embodied energy in the production of a mattress is astronomically high…It’s unbelievable to think that such a mindless item such as a mattress would take so much energy to produce from start to finish. “The cradle-to-gate primary energy requirements were around 33 billion MJ NCV. 1,780 MJ NCV [is] the embodied primary energy per average mattress and box spring set.”( Mattress and Box Spring Study) Considering roughly half the energy is derived from fossil fuels, this is a massive amount of consumed fossil fuels.
Through much research I have most definitely been enlightened by the overwhelming use of energy throughout the production process of a mattress. My research pertained to one specific item, and although quite limited in resources and statistics, it is shocking to know that average yearly production results a net energy use of 33 billion mega joules of energy derived from both fossil fuel and electricity. Prior to this project, I had no idea the overwhelming consumption product based industries consumed on a yearly basis. Considering my group chose to do our studies on a mattress surely does not help me sleep at night knowing I personally have contributed to such an enormous use of energy. The most unsettling part is that my research simply pertains to one item. It does not even begin to touch the tip of the iceberg of the product industry as a whole. As I look around at the objects we use on a daily basis, I wonder how much energy, how much waste, how many finite materials we have destroyed in the idea of simply decorating our living spaces. As a material society that focuses on rapidly accumulating and discarding objects, I begin to wonder how much do we waste in total? How can we better design objects so as to reduce waste, materials and energy consumption? The statistics about energy use in terms of recycling and waste were some of the most shocking to me. In my unrealistic imagination, when mattresses are disposed (or nearly any product for that matter) they are mostly recycled and materials are re-purposed. I never thought about the energy used to transport them to a facility or how much of the mattress is in fact recyclable but we do not invest to recycle them because, quite simply, the cost is too high for material separation. The results of my research were definitely eye opening. The amount of energy consumed should cause us to question our way of life, and think about how we live, and ultimately we should think about the cost we pay to have a good night rest.
1. "Mattress Production Process of Akant Ltd." YouTube. YouTube, 05 May 2009. Web. 13 Mar. 2014. video showing and explaining pocket spring manufacture process
2. "Tempur Sealy International, Inc. - Annual Report." Tempur Sealy International, Inc. - Annual Report. EDGAR Online, 21 Feb. 2014. Web. 13 Mar. 2014. data about mattress manufacture expenditures
3. "XIDENGBAO MATTRESS MACHINERY (GUANGZHOU) CO.,LIMITED CHINA XIDENGBAO MATTRESS MACHINERY CO.,LIMITED." Mattress Machines,Mattress Equipment,Pocket Spring Machine,Bedding Machinery, Bedding Equipment. N.p., n.d. Web. 13 Mar. 2014. This website contained all the information regarding standard manufacture automated machinery and electrical energy consumption by these machines
4. “Mattress and Box Spring Case Study: The Potential Impacts of Extended Producer
Responsibility in California on Global Greenhouse Gas (GHG) Emissions.” Mattress and Box Spring Case Study: The Potential Impacts of Extended Producer Responsibility in California on Global Greenhouse Gas (GHG) Emissions. California Department of Resources Recycling and Recovery (CalRecycle), 20 Nov. 2012. Web. 07 Feb. 2014. <http://www.calrecycle.ca.gov/publications/Documents/1430%5C20121430.pdf>. Provides detailed energy information pertaining to entire embodied energy from extraction to recycling/disposal
5. "Manufacturing Process of Mattress." Manufacturing Process of Mattress. Textile Exchange, n.d. Web. 07 Feb. 2014. <http://www.teonline.com/knowledge-centre/manufacturing-process-mattress.html>. provides information about some of the machines and processes of mattress manufacturing
6. Griffiths, Tony, Charles Coe, Fabio Fiori, and Ian Berry. “Mattress Recycling.” Waste and
Resource Management 166.4 (2013): 158-66. ICE, Nov. 2013. Web. 5 Mar. 2014. <https://vpn.lib.ucdavis.edu/,DanaInfo=ucelinks.cdlib.org,Port=8888+sfx_local?sid=EI:Compendex&genre=article&issn=1747-6526&date=2013&volume=166&issue=4&spage=158&epage=166&title=Proceedings+of+Institution+of+Civil+Engineers%3A+Waste+and+Resource+Management&atitle=Mattress+recycling&aulast=Griffiths&aufirst=Tony&isbn=>. source for information about the dumping and recycling of mattresses
Design 40A Winter 2014
Furniture Design: Coil Mattress
13 February 2014
Waste and Emissions of Coil Mattress
Until the 20th century, mattresses generally consisted of lumpy pads filed with horsehair, cotton, or rags. Lower class men and women had to rely on fabric sacks stuffed with straw or crop debris. In addition, these offered an inconsistent texture, and such mattresses were hard to clean, and often were filled with soil and insects (“All About Mattress Coils”). It wasn’t until the late 19th century when small manufacturers began to produce mattresses commercially. With the development of the box spring and John Boyd Dunlop creating a manufacturing technology that turned vulcanized rubber sap into latex foam, the design of the mattress evolved into what it is today (“The History of the Bed Mattress”). Yet, as the mass production of the commercial mattress as well as its comfort continues to increase, so does the waste and chemical production emitted from the production process.
Mattresses are generally consisted of two different layers, the comfort layer and the support layer. The comfort layer comprises of materials such as polyurethane foam, polyester fabric, and natural fibers. The support layer or innerspring unit as its called is created with a series of coils and springs. This support layer acts as the core of the mattress. Between the two primary layers is the upholstery, which is made of materials such as latex, polyurethane foams, and viscoelastic. In order for companies to pass fire regulations, these mattresses are then applied with fire retardants, which can be found in the comfort layers, support layers, or even both. These materials that consist of the mattress are composed to create a more comfortable and safe sleep atmosphere, but what the industrial companies are not telling us is the toxins and wastes that are emitted from these specific materials (“How Products Are Made”).
Polyurethane foam for example is the most commonly used material in the mattress construction. This material can be found in both the comfort layers and the upholstery. Although this material is the most popular, chemicals used in synthetic foams such as this one emit fumes. These fumes can cause reactions to people with chemical sensitivities. This process is known as off gassing ("Mattress Buyers Guide to Off Gassing"). An interesting experiment conducted on chemicals emitted from the mattresses was to test the correlation of respiratory tract irritations and polyurethane foams. To test the hypothesis that polyurethane foam from mattresses cause respiratory irritations and decreased airflow, four mattress consisted of polyurethane foams were created and Swiss Webster mice were then exposed to the emission given off from the mattresses for one to two hour periods. Results indicated that all four mattresses caused combinations of upper-airways irritation, lower-airways irritation and decreases in mid-expiratory airflow velocity in the mice With experiments such as this one, the conclusion that polyurethane foams causing harmful reactions is very clear. Since the mattress industry is not required by law to disclose the chemicals produced from polyurethane foams, companies are able to get away with these toxic chemicals emitted during production and distribution (Anderson et al., 2000).
Due to the high air permeability and the high inner surface area of the polyurethane’s foam structure causes this material to be highly flammable. Thus the need and application for fire retardants become a necessity. Yet, although these retardants are applied for fire safety, the use of halogenated flame retardants are not considered ideal due to high emission levels. One common substance in flame-retardants is boric acid. This substance is also known as a pesticide for killing cockroaches. Some of the other chemicals found in fire retardants are antimony and decabromodiphenyl oxide, which are both possible human carcinogens. Other toxic substances used in fire retardants on mattresses are Poly Brominated Diphenyl Ethers, also known as PBDE’S. Mattress manufacturers state that these chemicals stay trapped in the bed, but results speak otherwise. Small amounts of these chemicals seep through with the process of off gassing and the human body absorbs the toxins through both inhalation and through our skin. The issue of these chemicals does not come from the instant exposure of these toxins, but instead from the repetitive exposure which gradual leads to toxin buildups in the body. These toxin build ups cause harmful reactions to the human body which includes, dizziness, headaches, breathing difficulties, fatigue, nausea, and difficulty concentrating. Fire safety is a serious concern, but there are other ways than polluting our bodies with industrial toxins. Some possible replacements would be the use of organic mattress manufacturers who use natural substances instead of harmful chemicals for fire retardants (“A Toxic Fire Retardant Mattress”).
The metal coils that are located in the innerspring mattress are considered as the core of the bed. These coils are placed in order to provide stable back support. Without these coils, the mattress wouldn’t have any firmness to itself. The metal coils and springs provide a great source of support but it also enhances a dangerous type of pollution. Recent research has linked mattress coils to EMFs (electromagnetic fields) and radiation pollution. The connection is that the coils within the mattresses act as an antenna attracting and amplifying whatever radiation is circulating throughout your room. Antennas are nothing more than simple metal objects of appropriate length and size to match wavelengths of a specific frequency of electromagnetic radiation. Since the mattress’s springs are made of metal, and the length of a bed is exactly half the wavelength of FM and TV transmissions that are being broadcasted, the evidence that mattresses acting as antennas is very conceivable ("Your Mattress Could Be Acting as a Cancer-Causing Radiation Antenna").
The last materials that were considered harmful and gave chemical emissions came from the adhesive bonds and polyester fibers. The polyester fibers are found in the comfort layers of the mattress and the adhesives that bind the mattress layers and wood frames together contain formaldehyde, which is highly toxic. The adhesive bonds emit dangerous VOC’s (Volatile Organic Compounds) into the air, which are associated with symptoms such as rashes, headaches, and blurred vision. To further assist the theory that mattress adhesives release harmful toxins, a study in 2006 was performed on a memory foam mattress and a traditional innerspring mattress in which emissions from these beds were collected over a 96-hour period. In the end the memory foam mattress emitted 61 VOC chemicals whereas the innerspring mattress recorded 39 different chemicals. In addition to the formaldehyde chemical known in the adhesive bonds, other chemicals such as styrene, isopropyl benzene, limonene, trimethylbenzene, nitrobenzene, ethylbenzene and dichloridebenzene were found in the adhesives as well. Many of these chemicals are solvents and are listed as Class C carcinogens and are classified harmful by the EPA, The California Health and Wealth fare Agency, and the International Agency of Research of Cancer (IARC) (Brackman, 2010).
The adhesives that are binding the mattress layers are not the last material causing dangerous waste emissions but polyester fibers located in the comfort layers are producing just as, if not worse emissions. Polyester fibers are made from synthetic polymers that are made esters of dihydric alcohol and terpthalic acid, which means both of them are highly toxic and these toxins are not completely removed after the manufacturing process and find easy entry through the absorption of our body and inhalation similar to how the chemicals from the adhesives are consumed. Many health concerns have been confirmed due to the excessive use of these polyester fabric and fibers. Some of which are, chronic and severe respiratory infections as well as skin problems such as rashes, itching, redness, and dermatitis. In addition to human health risks, Polyester is very harmful and dangerous to the environment as well since polyester is hard to recycle or biodegraded and its production disposes toxins in the water and emits lots of pollutants in the air the ("Fashionbi 247." The Health Risks of Toxic Fibers and Fabrics.). However, although most mattresses contain materials that emit harmful toxins, there are still healthful and more beneficial alternatives for mattress choices. Some of these choices would be replacing materials with pure natural rubber latex in which the process of extracting the liquid latex is much like tapping maple trees for syrup. This process makes for a sustainable product and can be accomplished with no added chemicals. An innerspring mattress can also be developed naturally and non-off gassing with the use of a natural insulator, latex, wool, and/or with cotton layers ("Mattress Buyers Guide to Off Gassing"). Yet, even though we can aid in the reduction of toxic waste emissions from the materials, an even more difficult energy and waste emission presents itself and is focused towards a different target.
The transportation and distribution of the mattresses causes more environmental concerns than it does to humans. Most of the films and bags used to package mattresses and foundation during transportation and distribution are made of clear, pliant polyethylene. Other options include rigid polypropylene or jute boot bags, which are commonly imported from china. Since mattresses are dragged instead of carried across concrete plant floors, the film used to wrap them must be considerably strong and thick. Thus a petroleum-based “monolayer”, or single-layer plastic film is often used in addition to the polyethylene films. Extruders who work to produce these films are constantly devising stronger yet thinner resin formulations to help hold prices down, while still meeting mattress industry requirements for toughness. Although these films help prevent the mattress from getting ruined during the transportation process these present films and protective layers are not seen as “environmentally friendly” options since little if any recycled content is generally found in mattress films or bags ("Mattress Packaging Equipment to Keep Beds Clean, Costs down"). Although Polyethylene can be recycled, most of the commercial polyethylene ends up in landfills and in the oceans making the great pacific patch. Polyethylene is not considered biodegradable, as it takes several centuries until it is efficiently degraded ("Polyethylene Is Extremely Harmful"). Furthermore, plastics of polyethylene use around 6.45 kg of oil per kg, which results in 3.723kg of greenhouse gas emissions ("PET (polyethylene Terephthalate)"). In addition to the environmental impact, Polyethylene can also be harmful to humans as well. Potentially chemicals such as the plasticizer phthalate may leach from polyethylene. This chemical in particular has been associated with hormonal imbalances, increases in allergies, and reduced fertility. Other studies have shown that phthalate may also contribute to the development of obesity and breast cancer ("What Is Polyethylene?"). The polypropylene is also another form of plastic very similar to polyethylene. Although studies have shown that plastics made of polypropylene composites showcase no toxicity chemicals, the environmental damage is the same. Since polypropylene takes several centuries for natural degradation, most of these plastics end in landfills and pollute the environment with CO2 emissions. The materials and packaging of mattresses cause significant damage to both the environment and humans through its waste emissions, yet the greatest cause of waste production from mattresses comes from its life cycle. From beginning manufacturing until the end of the mattresses life to the mattresses reprocessing, waste continues to emit from the product and its contributors.
The 5 factors that out put the highest greenhouse gas emissions and energy contributions towards mattress production are iron and steel mills, power generations and supplies, truck transportation, oil and gas extraction, and other basic organic chemical manufacturing. These five factors together produce 94.4 kg of CO2 greenhouse gas emissions per production. The energy required in MJ for these five totaled 856.1. The statistics above showcase the amount of greenhouse gas and energy required for the production, manufacturing, and transportation of just a single mattress unit. These numbers were taken according to the trade and industry statistics in the U.S. in 2010 and during this year over 38 million mattresses and box spring units were sold. Of the 38 million mattresses and box springs, 3 million were considered as imports. The overall green house gas emissions produced from mattresses in 2010 equaled 2.4 million metric tons of CO2E, while the overall primary energy requirements were around 33 billion MJ NVC (“Mattress and box spring case study”). The contributors in the production of mattresses are creating drastic emissions and wastes as the mattress unit itself.
Once mattresses reach the end of their life cycle they most likely end up in a landfill. Primary energy demand and green house gas emissions come from the transportation of the mattress from their pickup location to the landfill, as well as the construction, maintenance, and operation of the landfill itself. Additional greenhouse gas emissions come from the chemical and biological degradation process of the mattress materials in the landfill. Yet an estimated 69.3 MJ and 8.3 kg CO2E are avoided whenever an entire set is reused instead of land filled. Additionally recycling diverts at least 85 percent of the mattress mass from landfills which estimates an additional energy and green house savings of 58.8 MJ and 7.1 kg CO2E, which is about 15 percent less than in a mattress reuse scenario. Although mattress recycling requires transportation as well as reprocessing of the products the cut in greenhouse gas emissions and energy wastes are significant. Together with energy and greenhouse gas data for light duty vehicles and combination trucks for the mattress transportation during the recycling period, results in primary energy demand of around 60 MJ and overall greenhouse gas emissions of roughly 4 kg CO2E per mattress set. Since automated disassembly in mattress recycling facilities is not used in recycling operations, manual disassembly is therefore required for recycling and reprocessing. This manual labor results in 8 MJ of primary energy per mattress and .55 kg of CO2 emissions (“Mattress and box spring case study”). Although the activities of recycling and reusing divert the end of life cycle of a mattress from the landfills, recycling of mattresses are uncommonly practiced and applied. In the end most of these mattresses are still sent to landfills to sit and produce constant greenhouse gas emissions and environmental waste (“Mattress and box spring case study”).
In conclusion the production and manufacturing of mattresses produce a significant amount of waste. Whether it is the materials releasing toxic wastes harmful to humans, the energy and environmental pollutants during the distribution and transportation, or the green house gas emissions emitted during the life cycle of a mattress, the wastes that is extruded is a very serious issue and one that should be taken of more concern. Yet, in recent years the push to minimize mattress waste has undoubtedly taken a turn for the better. With legislative pressuring manufacturers towards mattress recycling and the development of safer and non-toxic chemical and material replacements the waste cycle of the mattress will continue to diminish and the evolution of the mattress will continue to grow.
Anderson, Rosalind C., and Julius H. Anderson. "Respiratory Toxicity of Mattress Emissions in Mice." Archives of Environmental Health: An International Journal 55.1 (2000): 38-43. Print.
"ALL ABOUT MATTRESS COILS." All About Mattress Coils. Sit 'n Sleep, n.d. Web. 07 Feb. 2014. <https://www.sitnsleep.com/resources/article/all-about-mattress-coils>.
"A Toxic Fire Retardant Mattress." A Toxic Fire Retardant Mattress. N.p., n.d. Web. 08 Mar. 2014. <http://www.zenabode.com/fire-retardant-mattress.html>.
Brackman, Adam. "Is Your Mattress Toxic? (Hint: Probably)." Is Your Mattress Toxic? (Hint: Probably) | New Living. New Living, 7 July 2010. Web. 7 Feb. 2014. <http://www.newliving.net/uncategorized/mattress-toxic-hint/>.
EcoMall. "WHAT'S IN YOUR MATTRESS?" WHAT'S IN YOUR MATTRESS? - Ecomall. N.p., n.d. Web. 05 Mar. 2014. <http://www.ecomall.com/greenshopping/whitelotus.htm>.
"Fashionbi 247." The Health Risks of Toxic Fibers and Fabrics. N.p., n.d. Web. 08 Mar. 2014. <http://fashionbi.com/newspaper/the-health-risks-of-toxic-fibers-and-fabrics>.
Hartman, Eviana. "Mattress Eco-Matters: Don't Take It Lying Down." Washington Post. The Washington Post, 06 Apr. 2008. Web. 07 Feb. 2014. <http://www.washingtonpost.com/wp-dyn/content/article/2008/04/03/AR2008040303081.html>.
"How Products Are Made." How Mattress Is Made. N.p., n.d. Web. 08 Mar. 2014. <http://www.madehow.com/Volume-1/Mattress.html#b>.
"Manufacturing Process of Mattress." Manufacturing Process of Mattress. Textile Exchange, n.d. Web. 07 Feb. 2014. <http://www.teonline.com/knowledge-centre/manufacturing-process-mattress.html>.
Mast Business Directory. "Factors That Need Consideration While Starting Manufacturing for Beds and Mattresses." Mast Business Directory. Mastbusiness.com, n.d. Web. 07 Feb. 2014. <http://www.mastbusiness.com/bizarticles/ba465/>.
"Mattress and Box Spring Case Study: The Potential Impacts of Extended Producer Responsibility in California on Global Greenhouse Gas (GHG) Emissions." Mattress and Box Spring Case Study: The Potential Impacts of Extended Producer Responsibility in California on Global Greenhouse Gas (GHG) Emissions. California Department of Resources Recycling and Recovery (CalRecycle), 20 Nov. 2012. Web. 07 Feb. 2014. <http://www.calrecycle.ca.gov/publications/Documents/1430%5C20121430.pdf>.
"Mattresses and Box Springs." Organic Grace. Organic Grace, n.d. Web. 07 Feb. 2014.
"Mattress Buyers Guide to Off Gassing." Articlesbase.com. Articlesbase.com, 17 Dec. 2008. Web. 07 Feb. 2014. <http://www.articlesbase.com/sleep-articles/mattress-buyers-guide-to-off-gassing-688552.html>.
"Mattress Construction." Mattress InformationMattress Construction. N.p., n.d. Web. 07 Feb. 2014. <http://matresses101guide.com/Mattress_Information_Mattress_Construction.html>.
"Mattress Packaging Equipment to Keep Beds Clean, Costs down." BedTimes. N.p., n.d. Web. 08 Mar. 2014. <http://bedtimesmagazine.com/2009/03/mattress-packaging-equipment-to-keep-beds-clean-costs-down/>.
"Mattress Stewardship Briefing Document." Product Stewardship Institute, Inc. | Mattress Stewardship Briefing Document. Product Stewardship Institute, Inc., 25 July 2011. Web. 7 Feb. 2014. <http://www.productstewardship.us/associations/6596/files/Mattress_Stewardship_Briefing_Document_FINAL.pdf>
Pepper, Dan. "How Products Are Made-Mattress." How Mattress Is Made. Advameg, Inc., n.d. Web. 07 Feb. 2014. <http://www.madehow.com/Volume-1/Mattress.html>.
"PET (polyethylene Terephthalate)." Environmental Impact. N.p., n.d. Web. 08 Mar. 2014. <http://envimpact.org/node/14>.
"Polyethylene Is Extremely Harmful." - TRCB. N.p., n.d. Web. 08 Mar. 2014. <http://www.trcb.com/news-and-society/environmental/polyethylene-is-extremely-harmful-1899.htm>.
Sefcik, Lisa. "Box Spring Mattress Fact Sheet." Overstock.com: Online Shopping. Overstock.com, n.d. Web. 07 Feb. 2014. <http://www.overstock.com/guides/box-spring-mattress-fact-sheet>.
"The History of the Bed Mattress." The History of the Bed Mattress. N.p., n.d. Web. 01 Mar. 2014. <http://www.slideshare.net/radar0arrow/the-history-of-the-bed-mattress>.
"Your Mattress Could Be Acting as a Cancer-Causing Radiation Antenna." Mercola.com. N.p., n.d. Web. 10 Mar. 2014. <http://articles.mercola.com/sites/articles/archive/2010/08/18/your-box-spring-mattress-could-be-acting-as-a-gigantic-cancercausing-radiation-antenna.aspx>.
"What Is Polyethylene?" WiseGEEK. N.p., n.d. Web. 07 Mar. 2014. <http://www.wisegeek.org/what-is-polyethylene.htm>.
Whitney, Nicole. "Innerspring Mattress Information." Innerspring Mattress Information | EHow. Demand Media, 25 June 2010. Web. 07 Feb. 2014. <http://www.ehow.com/about_6657734_innerspring-mattress-information.html>.