A Review of the Effectiveness of Respirators in Reducing Exposure to Polycyclic Aromatic Hydrocarbons for Coke Oven Workers

Objectives: In 2011 recommendations for the prescription of lung cancer in coke oven workers were made in the UK. In the 1970s, a powered helmet respirator, the Airstream helmet, was introduced to the UK coking industry with the aim of reducing exposure to polycyclic aromatic hydrocarbons (PAH) aerosols and consequent lung cancer risks for workers on the coke oven tops. This review set out to identify the level of protection afforded by the Airstream helmet, when the helmets could be considered to have provided effective protection and whether the levels of protection have been maintained to the current time. Methods: Five approaches were taken to identify review material, including searching the peer-reviewed and grey literature; searching material held in the National Archive; using a Freedom of Information to the Health and Safety Executive; interviews with employees involved in the introduction of the Airstream helmet; and acquisition of company reports. Results: The two principal companies involved in coke production in the UK took different approaches to the introduction of the Airstream helmets. Because of this, it can only be considered that effective wearing occurred in the industry as a whole from 1982 onwards. Exposure measurements made by British Steel in the late 1970s suggested that the mean protection factor of the Airstream helmet was similar to 10 (5th percentile similar to 2.5), regardless of whether exposure was assessed as the inhalable aerosol or other measures more specific to aerosol of PAH. More recent data collected using biological monitoring has identified that average urinary levels of 1-hydroxypyrene (1-HP) generally correspond with the inhalation occupational exposure limit for benzene soluble material. Although on occasions, relatively high air concentrations in-mask and urinary 1-HP concentrations have been identified, underlining the necessity to maintain close supervision of workers wearing respirators. Conclusions: Overall, we concluded that the wearing of helmet respirators has effectively controlled long-term average exposure to PAH for most workers on coke ovens since 1982.