A study of particulate emissions during 23 major industrial fires: Implications for human health

Public exposure to significantly elevated levels of particulate matter (PM) as a result of major fires at industrial sites is a worldwide problem. Our paper describes how the United Kingdom developed its Air Quality in Major Incidents (AQinMI) service to provide fire emission plume concentration data for use by managers at the time of the incident and to allow an informed public health response. It is one of the first civilian services of its type anywhere in the world. Based on the involvement of several of the authors in the AQinMI service, we describe the service's function, detail the nature of fires covered by the service, and report for the first time on the concentration ranges of PM to which populations may be exposed in major incident fires. We also consider the human health impacts of short-term exposure to significantly elevated PM concentrations and reflect on the appropriateness of current short-term guideline values in providing public health advice. We have analysed monitoring data for airborne PM (≤10microm, PM₁₀;≤2.5microm, PM_2.5 and ≤1.0microm, PM₁) collected by AQinMI teams using an Osiris laser light scattering monitor, the UK Environment Agency's 'indicative standard' equipment, during deployment to 23 major incident industrial fires. In this context, 'indicative' is applied to monitoring equipment that provides confirmation of the presence of particulates and indicates a measured mass concentration value. Incident-averaged concentrations ranged from 38 to 1450microgm^-3 for PM₁₀ and 7 to 258microgm^-3 for PM_2.5. Of concern was that, for several incidents, 15-min averaged concentrations reached >6500microgm^-3 for PM₁₀ and 650microgm^-3 for PM_2.5, though such excursions tended to be of relatively short duration. In the absence of accepted very short-term (15-min to 1-h) guideline values for PM₁₀ and PM_2.5, we have analysed the relationship between the 1-h and 24-h threshold values and whether the former can be used as a predictor of longer-term exposure. Based on this analysis, for PM₁₀, our tentative 1-h threshold value for use in deciding whether to close public buildings or to evacuate areas is 510microgm^-3. For PM_2.5, 1-h concentrations exceeding 350microgm^-3 might indicate longer-term exposure problems. We conclude that whilst services such as AQinMI are a positive development, there is a need to consider further the accuracy of the data provided and for the development of very short-term guideline values (i.e. minutes to hours) that responders can use to determine the appropriate public health response.