All organic materials (that is, everything containing carbon) can burn. When burned, they release smoke, which contains many different combustion products, mainly gases, virtually all of which are toxic. Among those toxic gases, some - such as carbon monoxide (CO) and hydrogen cyanide (HCN) - are narcotic. Others are irritants - such as hydrogen chloride (HCl) and acrolein. Scientific tests show that combustion byproducts from most burning materials are highly irritant. In this respect, vinyl represents no unusual hazard.¹

The most dangerous substances are the narcotic gases because they can cause drowsiness, followed by unconsciousness and death by asphyxiation. CO is especially dangerous because of the abundant levels produced by virtually all burning materials and the low levels that cause death. The hazard of CO is made much worse by the fact that it is a colorless and odorless gas that provides no warning of its presence.²

Typical combustion products of vinyl are CO, carbon dioxide and HCl which, unlike CO, is an irritant gas with a pungent odor.³ Claims that synthetic materials such as vinyl produce unusually toxic decomposition materials when they burn are not substantiated by research.⁴ Overall, vinyl has excellent fire properties and is at least as safe as the majority of other materials in most fire situations.

Fire Deaths Down, Plastics Up
While the growing presence of synthetic materials - including vinyl - has sometimes been blamed for creating a more lethal fire environment, in fact 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).⁵ 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, which actually stops fires from starting and from spreading because of the inherent flame resistance it gets from its chlorine content - deserves part of the credit for this improvement.

Modern buildings contain many materials such as paper, textiles, plastics and wood, which will act as fuel in a fire. Under the intense heat of most serious fires, materials which normally would not be considered combustible (aluminum, for example) may burn. But it is the extent to which they support combustion that differs. Many vinyl formulations used in building products (especially rigid or unplasticized vinyl) are difficult to ignite. Once ignited, they will continue to burn only while a flame is applied.⁶ These products produce significantly less smoke than their alternatives, which can be critical for people trying to escape a burning building. They also out-perform many other common building materials in flame spread and heat release.^7,8

Other factors are equally important. For example, vinyl conduit and trunking used to enclose and protect cable provide a fire-resistant enclosure, which helps maintain the integrity of electrical wiring in the event of a fire.⁹

Testing Resolves Toxicity Issue
Irritants such as HCl usually are felt at low concentrations and may produce the earliest effects of exposure in a fire. These include painful effects on the eyes and upper respiratory tract that make breathing difficult. Research on baboons, which are anatomically similar to humans, has demonstrated that short exposures to relatively high concentrations of HCl are not disabling. Primates, in fact, can survive short exposures to these irritant gases without being incapacitated or losing the ability to escape.¹⁰ Although HCl causes irritation of the upper respiratory tract, there is no evidence of long-term damage to lung or pulmonary function except in very high concentrations.¹¹

Additional study has shown that, since vinyl is usually a small proportion of the mass of materials in most buildings, the narcotic gases CO and HCN present a far more serious hazard in most fires than HCl exposure. In hundreds of autopsies conducted on fire victims in the United States, not one death has been linked to the presence of vinyl.

Concerns also have been raised about micro-pollutants such as dioxins as a result of accidental fires involving vinyl. However, systematic investigations of large-scale accidental fires in Germany, Sweden and Canada have indicated that dioxins will be produced in accidental fires whether vinyl is present or not, and that the quantities produced in such fires posed no threat to human health or to the environment.^12,13 A recent, published, industry analysis of vinyl's fire performance found that house fires involving the combustion of vinyl products most likely contribute less than half a gram per year to overall airborne dioxin emissions.¹⁴ The conclusions support other studies of accidental fires.¹⁵

Testing Addresses Corrosion
It also has been suggested that fire gases from burning vinyl products are unusually corrosive because of the HCl content which, when mixed with water, produces hydrochloric acid and may cause structural damage to buildings. Full-scale fire tests carried out at the United Kingdom Fire Research Station have indicated that it is the heat generated by fires, and not chemical reactivity, which can distort or weaken steel structures. In fact, all fire effluent is corrosive to some degree. In real-life situations, ease of ignition, rate of burning and heat release may be more important than the effects of combustion shown in smaller scale testing.¹⁶

Moreover, questions have been raised about smoke corrosivity test methods for communications cables. Current methods fail to accurately predict the electronic reliability of digital equipment, since it has been found that equipment failure usually results from the degradation of insulation resistance rather than direct metal loss. Research performed by Lucent Technologies has demonstrated that the fire properties of the material - not whether it burns - are critical to electronic reliability. Several vinyl compounds produce excellent results when tested by the Electronic Reliability (ER) procedure (now UL 1985), and Lucent prefers vinyl jacketing to other products.¹⁷

1 “PVC in Fires,” The British Plastics Federation, London, April 1996, 12.

2 “CO Poisoning – Know the Symptoms,” NFPA Journal, Vol. 91, No. 6, November-December 1997.

3 Lt. Kevin Mellott, “Fireground demo refutes misconceptions about PVC and fire,” Fire Chief Magazine, October 1984.

4 “PVC in Fires,” 11.

5 Statistics from the National Fire Protection Association.

6 Frank L. Fire, “Plastics – Some Facts Fire Fighters Should Know,” Fire Engineering, February 1984.

7 V. Babrauskas and R. D. Peacock, “Heat release rate: The single most important variable in fire hazard,” Fire Safety Journal, 18, 255-72, 1992; M.M. Hirschler, “Heat release from plastics,” Chapter 12 a, 375-422, Heat Release in Fires, Elsevier, London, UK, Eds. V. Babrauskas and S.J. Grayson, 1992.

8 “PVC in Fires,” 9-10.

9 M.J. Scudamore, P.J. Briggs, F.H. Prager, “Cone calorimetry – A review of tests carried out on plastics for the Association of Plastic Manufacturers in Europe,” Fire & Materials, Vol. 15, 65-84, 1991.

10 H.L. Kaplan, W.G. Switzer, R. K. Hinderer, A. Anzueto, “Studies of the Effects of Hydrogen Chloride and Polyvinylchloride (PVC) Smoke in Rodents,” Journal of Fire Sciences, November/December 1993, Vol. 1, No. 6.

11 H.L. Kaplan, W.G. Switzer, R. K. Hinderer, A. Anzueto, “A Study on the Acute and Long-Term Effects of Hydrogen Chloride on Respiratory Response and Pulmonary Function and Morphology in the Baboon,” Journal of Fire Sciences, November/December 1993, Vol. 11, No. 6.

12 “PVC in Fires,” 2.

13 “Tests rule out dioxin fears,” The Hamilton Spectator, Sept. 27, 1997, Hamilton, Ontario.

14 W.F. Carroll, Jr., et al, “Is PVC in House Fires the Great Unknown Source of Dioxin?” Fire and Materials, 20, 161, 1996.

15 Drs. Englemann and Skura, “PVC in Accidental Fires: The Formation of Dioxins and Furans,” Hoechst AG, Gendorf, May 1992, English translation.

16 “PVC in Fires,” 13.

17 J.T. Chapin and P. Gandhi, “Comparison of LAN Cable Smoke Corrosivity by US and IEC Test Methods,” submitted to National Fire Protection Research Foundation, Fire Risk & Hazard Research Application Symposium, San Francisco, Calif., June 25-27, 1997.