July 4 Fireworks to Add to Air Pollution Amid Canadian Wildfires

The Fourth of July is known for fireworks, but although they're fun to watch, pyrotechnics could greatly impede U.S. air quality as the smoke mingles with that from the ongoing Canadian wildfires.

Canada is on track to experience its worst wildfire season ever, with blazes continuing to burn through Quebec, western Ontario and Alberta. The fires have been so severe that they've significantly affected air quality in the United States, with smoke shrouding cities over 1,000 miles away in a haze.

Fireworks, meanwhile, spew out harmful pollutants that can mimic the smoke from wildfires. The July Fourth displays may worsen air quality problems in U.S. areas already dealing with wildfire smoke from the Canadian fires. In addition to Canada, wildfires are burning in Colorado and Washington, contributing to the pollution.

Much of the smoke has dissipated in the U.S., where air quality started to improve over the past weekend. But meteorologists are anticipating that Fourth of July fireworks will add to any remaining pollution.

Air quality is measured on an index that ranges from 0 to 500. Index values of 0 to 50 are considered "good," with 51 to 100 "moderate" and 101 to 150 considered "unhealthy for sensitive groups," such as those with asthma. The danger continues to worsen as the index rises, with 151 to 200 considered "unhealthy," 201 to 300 "very unhealthy" and 301 to 500 considered "hazardous."

AccuWeather senior meteorologist Alan Reppert told Newsweek that fireworks alone can worsen air quality to "unhealthy" or "very unhealthy" on the index.

While much of the U.S. has emerged from the haze since last week, areas of the Pacific Northwest are still struggling with air quality affected by the wildfire smoke. Reppert said he anticipates that some smoke pushing into parts of Washington, Oregon, Montana and Idaho will interact with the firework smoke, causing increased pollution.

"It's clearly visible with graphs," Reppert said about the worsening air quality from fireworks.

Depending on the weather, it can take more than a day for the fireworks pollution to dissipate. Wildfire smoke, meanwhile, may affect parts of the U.S. intermittently.

"We will still see intrusions through most of the summer with wildfire smoke," Reppert said.

However, it's difficult to predict when smoke pollution will occur on a long-term basis.

Last week, the Midwest struggled greatly with the wildfire smoke. Indianapolis, Detroit, Chicago and Cleveland all experienced unhealthy air quality for several days. Air quality levels have since improved to moderate or good in most areas, a substantial improvement from the unhealthy classification that plagued several states during the week.