July 4th is marked by displays of fireworks and this, according to a new study, sparks an increase in air pollution that could pose threats to human health.

The National Oceanic and Atmospheric Administration (NOAA) study revealed that for a brief period between the evening of July 4 and morning of July 5, air pollution temporarily increases with the amount of fine particles in the air increasing by 42 percent across the country.

Increase in air pollution was likewise found to be highest in areas next to where the fireworks were shot off showing an increase of 370 percent.

For the study published in the journal Atmospheric Environment, the researchers analyzed the concentration of fine particles in the air on July 4 and then compared this to days before and after. They found that the levels of concentration peaked at more than double their average between 9 and 10 p.m. on July 4 and this concentration did not drop to background levels at around 12 p.m. on July 5.

"Hourly PM2.5 concentrations during the evening of July 4 and morning of July 5 are higher than on the two preceding and following days in July, considered as control days," study researchers Dian Seidel, from NOAA Air Resources Laboratory, and Abigail Birnbaum, from the Cooperative Institute for Climate and Satellites-Maryland wrote. "The national average increase is largest (21 μg/m3) at 9-10 pm on July 4 and drops to zero by noon on July 5."

At an observing site in Washington, D.C, the average PM2.5 concentration was around 40 percent higher than average on July 4 and this level surged by more than 400 percent between 8 to 10 p.m. At one of the sites in Ogden, Utah, the concentration increased by 370 percent on July 4 and increased by more than 370 percent by 10 p.m.

The fine particles are considered as a health risk since they can get stuck in the lungs, and once there, can damage the lungs, heart and blood vessels. The risk increases if a person is exposed over long periods of time.

The Environmental Protection Agency (EPA) said that studies have shown a link between exposure to these fine particles and premature death from lung and heart disease. Effects of exposure can also lead to increased visits to the emergency room, hospital admissions and absences from school or work. Children and older adults are particularly sensitive to fine particle exposure.

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