Major air pollution incidents and a model for estimating the risk from acute particulate exposure on public health

The UK developed its Air Quality in Major Incidents (AQiMI) project to provide fire plume concentration data for use by responders during major industrial fires. Based on the involvement of the authors in the AQiMI project we: describe the project’s function, detail the nature of these fires, and report the concentration range of particulates that populations may be exposed to. We reflect on the appropriateness of current short-term guideline values in providing public health advice. Monitoring data for PM10, PM2.5, and PM1, collected by AQiMI teams during deployment to 23 major incident industrial fires has been analysed. Incident-averaged concentrations ranged: 38 to 1450 μg m-3 PM10 and 7 to 258 μg m-3 PM2.5. For several incidents, 15-minute averaged concentrations reached more than 6,500 μg m-3 for PM10 and 650 μg m-3 for PM2.5. In the absence of accepted very short-term (15 minutes to 1 hour) guideline values for PM10 and PM2.5, we have analysed the relationship between the 1-hour and 24-hour 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-hour threshold value for use in deciding whether to close public buildings or to evacuate areas is 510 μg m-3. For PM2.5, 1hr concentrations exceeding 350 μg m-3 might indicate longer-term exposure problems. We conclude that AQiMI are a positive development but there is a need to consider the accuracy of the data provided and to develop very short-term guideline values (i.e. minutes to hours).