FOCUS
Lethal exposure Anna Stec examines potential long term toxic and carcinogenic risks from unwanted fires to firefighters, the public, fire survivors and buildings
I
N THE UK every year, unwanted fires kill hundreds of people, leave thousands injured and destroy property – but the real cost has been signifi cantly underestimated. Firefi ghters have presented with abnormally high levels of cancer and other diseases; fires leave toxic residues in buildings and the environment, contribute at least 10% to the crisis in urban air quality, and adversely affect the long term health of residents, bystanders and the population exposed to the smoke. Unwanted fi res are predominantly diffusion
fl ames with poor fuel air mixing, leading to a wide range of products of incomplete combustion. These range from polymer fragments, small organic molecules and oxygenated organic molecules to larger polycyclic aromatic hydrocarbons (PAH) and particulate matter (PM). In contrast, burning for energy release – such as in an engine or power station – involves premixed fl aming in which the fuel and air are suffi ciently well mixed and almost all the effl uent is carbon dioxide and water. Thus, unwanted fi res make a disproportionate contribution to atmospheric pollution, soil and water contamination and post fire contamination of buildings.
34 MARCH 2020
www.frmjournal.com They produce a blend of toxic, irritant and
carcinogenic species which vary depending on the specific materials burning and the fire conditions. While carbon monoxide (CO), hydrogen cyanide (HCN) and acid gas irritants have immediate adverse effects on health, most other toxicants result in longer term conditions such as cancer, cardiovascular and neurological diseases, which become more likely with repeated exposure to the toxicants. The table in Figure 1 (on page 35) shows longer term effects. Regardless of the fuel, carcinogens
such as benzene and PAHs are released in almost all fires. Polychloro and polybromo- dibenzodioxins and dibenzofurans (PCDD/Fs and PBDD/Fs) (‘dioxins’) and polychlorinated biphenyls (PCBs) form readily when halogens are present in the fuel; respiratory sensitisers such as isocyanates are released during burning of polyurethanes; and toxic heavy metals (lead, cadmium etc) are often present in fi re effl uents. Unlike gas molecules, which travel at
around 1 km/s – frequently colliding with the upper respiratory tract during inhalation
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