Out of all plastics, PVC is the most widely used in buildings, such as drinking water and waste water pipes, window frames, flooring and roofing foils, wall coverings, cables etc. Like all other organic materials used in buildings (other plastics, wood, clothing etc.), PVC products will burn when exposed to enough heat. However, unlike these other materials PVC products are naturally self-extinguishing, i.e. if the ignition source is withdrawn they will stop burning. Because of its high chlorine content PVC products have burning characteristics, which are quite favourable, i.e. they are difficult to ignite, the heat production is comparatively low and they tend to char rather than generate flaming droplets.
But if there is a large enough fire in a building PVC products will start to burn and will emit toxic substances like any other organic material.
The most dangerous toxicant emitted during fires is carbon monoxide (CO), which is responsible for 90 to 95% of deaths from fires. CO is a subtle killer, since it has no odour. Most people die in fires while sleeping. And of course CO is emitted by all organic materials, be it wood, textile or plastics.
PVC, as well as some other materials, also emits acids, organic or inorganic ones. These emissions can be smelled and are irritating, rapidly alerting people to the presence of fire. A specific acid, hydrogen chloride, is connected with burning PVC and few other products. To the best of our knowledge, no fire victim has ever scientifically been related to HCl poisoning.
Some years ago no big fire was discussed without dioxins playing a major role both in communication and measuring programmes. Today we know that dioxins emitted in fires do not impact people, since people exposed to fire have been examined in several studies. The dioxin levels measured in these studies were never elevated against background levels. This very important fact has been recognised by official reports. And we know that many other carcinogens are emitted in fires, such as polycyclic aromatic hydrocarbons (PAH) and fine particles, which present a much higher hazard than dioxins.
So there are very good reasons to go on using PVC products in buildings, since they perform well technically, have good environmental and very good economic properties, and do not make any greater contribution than other materials to the toxicological impact of fires.
