Fourth of July Fireworks Cause a Spike in Particulate Matter and Air Pollution

The Fourth of July may not just be known for fireworks. It could also be known for increased levels of particulate matter. Scientists have found that as explosions light up night skies, air pollution may worsen.

"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," said Dan Seidel, senior scientists at NOAA's Air Resources Laboratory, in a news release. "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 researchers focused their study on fine particulate matter, which are particles that are two and one half microns in diameter (PM2.5). They monitored these particles using 315 air quality monitoring sites that operated from 1999 to 2013.

So what did they find? The new research reveals that hourly concentrations of fine particulate matter typically reach their highest levels, when compared to the day before and after July 4, on the evening of July 4. However, levels drop back down by noon on July 5.

On average, the largest increases of fine particulate matter occur from 9 to 10 p.m. on the holiday. Average concentrations over the 24-hour period starting at 8 p.m. on July 4 are also 42 percent greater than on the days preceding and following the holiday.

The findings reveal a bit more about how this holiday can impact air quality. And while air quality varies from region to region, it's still important to note how spikes occur. The EPA recommends that people who are sensitive to particle pollution try to limit their exposure by watching fireworks from upwind.

The findings are published in the journal Atmospheric Environment.

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