Vinyl has excellent fire properties.
Vinyl building products are based on a polymer that, by its nature, resists combustion. 1 Rigid vinyl building products are slow to ignite, their flame spread is slow, and they cease to burn after the flame source is removed. Flexible vinyl building products may contain plasticizers which are flammable in themselves, but either because the amounts are sufficiently low or because the materials also contain fire retardants, most flexible vinyl building products also resist burning. Indeed, vinyl is one of the few materials meeting the stringent National Fire Protection Association (NFPA) requirements for insulating electrical and data transmission cables, including in plenum applications.
All organic materials – that is, materials based on carbon – can burn under the right conditions and, when burning, will produce toxic byproducts of combustion. Fire scientists recognize that the largest hazard in a fire is carbon monoxide (CO), a gas produced in abundance by virtually all burning materials. 2 CO is a narcotic, causing drowsiness. It can cause death at low levels. The hazard of CO is made worse by the fact that it is colorless and odorless, providing no warning of its presence.
When vinyl does burn, it typically produces CO, carbon dioxide and hydrogen chloride (HCl). 3 The specific toxicity of inhaled HCl is similar to that of CO; however, unlike CO, HCl is an irritant gas with a pungent odor, giving warning of its presence. Moreover, HCl does not persist in the fire atmosphere as CO does. Rather, in real fires HCl air concentration declines rapidly as it adheres to or condenses on surfaces. HCl sampling in real fires shows that it tends not to reach dangerous concentrations. 4, 5, 6, 7, 8
Some allege that HCl, an acid, on metallic surfaces can cause corrosion. Surprisingly, studies have also shown that the heat from a fire itself has an even greater corrosive effect on building materials. 9
Fire Deaths Down, Plastics Use Up
In the 1980s, some people speculated that the growing presence of synthetic materials – including vinyl – created a more lethal fire environment. While it is true that fire loads (furniture, carpeting and other materials) in residences are greater than they were in the 1940s, the U.S. fire death rate is decreasing, dropping from a rate of 76 per million in the 1940s (when most construction and decorative products were made of “natural” materials), to 15 per million in the 1990s (by which time vinyl and other plastics had replaced natural materials in numerous applications). 10 This downward trend can be attributed in large part to improved building codes and the broader use of sprinkler systems and smoke detectors. However, the increased use of more fire-resistant materials – like vinyl – also deserves part of the credit.
Some concerns have been raised about pollutants such as dioxin produced as a result of accidental fires involving vinyl. However, systematic investigations of large-scale accidental fires have indicated that dioxins are produced whether vinyl is present or not. 11, 12, 13, 14 The quantities detected in those fires posed no threat to human health or the environment. Recent published industry studies found that wood and vinyl as used in typical homes would contribute approximately equal amounts of dioxin in a house fire, 15 and that total dioxin emissions from all U.S. house fires would add up to only about 1 gram per year. 16
The best way to prevent accidental fires is to install smoke alarms to alert occupants, and in commercial buildings, sprinklers, to extinguish fires that do occur. Early detection and suppression saves lives.
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