The impact of Independence Day fireworks on atmospheric fine particulate matter in the contiguous United States

Abstract

Fireworks are pyrotechnics known for their bright displays during July 4th Independence Day celebrations in the US. However, their popularity comes with inherent hazards to human safety, including the potential for fires, explosions, and less well-known negative effects on air quality. Fireworks can emit fine particulate matter (particle diameters < 2.5 μm, PM2.5), posing significant health risks, particularly contributing to respiratory and cardiovascular illnesses. Hourly observed PM2.5 from 2001 to 2021 was gathered from the EPA’s AQS databases for analyzing the impact of fireworks during Independence Day on the PM2.5. The hourly PM2.5 from US Independence Days served as the experimental group while the average hourly PM2.5 concentration for the month of July in the last 20 years acted as a control. Observational differences were processed from both groups, focusing on large cities, and subsequently mapped to effectively visualize the spatial distribution. The PM2.5 concentration shows a significant increase during the evening of July 4th, especially at 9 to 11 PM local time with a larger increase in populous cities, eventually declining the following day. Drawing on the data and considering annual firework consumption, we estimated the PM2.5 emissions from Independence Day fireworks. Our study aims to analyze the influence of Independence Day fireworks on PM2.5, the trend during the past 20 years, and estimate the PM2.5 emissions from fireworks on July 4 for the first time, potentially improving the air quality modeling with an emission source that is not included before, shedding light on the environmental impact of fireworks and guiding measures to mitigate their adverse effects.