July 4th has been celebrated as the birth of American independence since 1776. Tonight, the sky will be illuminated with stunning fireworks displays that are taking place all over the US. But according to a new study, such festivities may have an unintended consequence – a significant increase in air pollution.
Published in the journal Atmospheric Environment, the study identifies a rise in fine particulate matter, or PM2.5 – particles that are 2.5 micrometers in diameter and smaller – on the evening of July 4th and the morning of July 5th.
According to the US Environmental Protection Agency (EPA), these small particles are a health concern; they can easily pass through the throat and nose to the lungs, which can trigger shortness of breath, coughing, wheezing and asthma attacks, as well as long-term health effects – such as stroke and heart attack and death from lung and heart disease.
It is well known that fireworks can present health risks. Last year, a Spotlight feature from Medical News Today noted that firework injuries – such as burns and other injuries to the hands, eyes and legs – increased by 30% compared with the previous year.
According to the researchers of this latest study – including Dian J. Seidel of the National Oceanic and Atmospheric Association (NOAA) Air Resources Laboratory in College Park, MD – previous studies had identified increases in air pollutants during and following fireworks displays.
“But no study to date has explored fireworks’ effects on air quality over large regions using systematic observations over multiple years to estimate typical regional PM [particulate matter] increases,” they note.
Seidel and study co-author Abigail N. Birnbaum, of the University of Maryland and student intern at NOAA, set out to address this research gap, assessing the air quality of 315 sites across the US on every 4th July between 1999 and 2013.
“We chose the holiday, not to put a damper on celebrations of America’s independence, but because it is the best way to do a nationwide study of the effects of fireworks on air quality,” says Siedel.
The researchers analyzed the hourly concentrations of fine particulate matter on the evening of July 4th, comparing them with those of the days before and after,
The team found that on average, concentrations of fine particulate matter were 42% higher on the evening of July 4th, compared with the days before and after the holiday. Levels reached their highest between 9 pm and 10 pm, with increases beginning at 8 pm. The increases lasted until around midday on July 5th.
The researchers identified variations in PM2.5 concentrations between air quality monitoring sites, which appeared to be dependent on weather conditions and how close the fireworks were to the site.
For example, concentrations were around 370% higher on the evening of July 4th at one site where the fireworks were set off in a field adjacent to it – which the team says is at a level well above the maximum 24-hour limit of 35 mcg per cubic meter set by the EPA.
Commenting on the findings, Seidel says:
“These results will help improve air quality predictions, which currently don’t account for fireworks as a source of air pollution. The study is also another wake-up call for those who may be particularly sensitive to the effects of fine particulate matter.”
The team notes that while the EPA do not regulate fireworks, they do recommend that individuals who are sensitive to air pollution – such as those with asthma – watch fireworks displays from a distance and ensure they have any required medication to hand.