Effects of Outdoor Pyrotechnic Displays on the Regional Air Quality of Western Washington State

Data from a PM₂₅ (i.e., D_p < 2.5 mm) particulate matter monitoring network was used to quantify the effects of outdoor pyrotechnic displays on the regional air quality of western Washington State. Linear regression and principal component analysis demonstrated that the fine par-ticulate matter generated by these displays was primarily composed of Sr, K, V, Ti, Ba, Cu, Pb, Mg, Al, S, Mn, Zn,and soot. The maximum 24-hour averaged PM_2.5 mass concentration apportioned to the pyrotechnic displays by absolute principal component scores regression analysis was 18.5 mg/m³. The majority of this mass (54%) was composed of K and S, which originated from the combustion of black powder. The distribution of smoke emissions from the displays closely resembled the population distribution of western Washington. The PM_2.5 aerosol monitoring network tracked the pyrotechnic smoke plume for a period of two days as it was advected by low-level winds. The geometric mass mean diameter of the K particles was ~0.7 mm after transport of ~100 km. In the absence of rain, which is the primary sink for particles of this size, the particulate matter generated by the pyrotechnic displays could have an atmospheric residence time of more than one week.