U.S. and Canada Wildfires Send Hazardous Smoke Across Multiple States, Affecting Air Quality for Millions

The air quality crisis in the United States intensifies as wildfires in Canada and the western US release a significant amount of smoke, affecting numerous regions across the country. This issue is expected to persist for several days.

Air quality alerts have been issued on Tuesday for over 11 states in the Midwest and Northeast due to Canadian wildfire smoke, although the concentration levels are slightly lower compared to Monday. Despite this decrease, it remains a significant health concern, particularly for individuals with respiratory issues, children, and the elderly.

Simultaneously, wildfires in western US states have contributed to deteriorating air quality, notably impacting Southern California where firefighters are battling the state’s largest blaze of the year.

The climate change-induced weather conditions favorable for wildfire propagation – dry air and strong winds – are increasingly common in parts of Canada and the US. This escalates the intensity of extreme North American wildfires, exacerbating their impact on public health.

As of Tuesday morning, over 500 uncontrolled wildfires were reported in Canada by the Canadian Interagency Forest Fire Centre, with 140 burning in Manitoba and more than 70 in Saskatchewan. The smoke from these fires, along with those in neighboring provinces, flowed southward over the weekend following a powerful cold front that dissipated intense July heat across the eastern two-thirds of the US.

The subsequent development of an area of high pressure trapped this smoke in the Midwest and Northeast. As a result, air quality started the week with dismal levels in these regions, ranking Detroit among the top three global cities for worst air quality on Monday. Early Tuesday morning, Detroit’s air quality ranked sixth-worst worldwide, according to IQAir.

Wildfire smoke contains hazardous, minute pollutants known as PM2.5 that can penetrate deep into the lungs or enter the bloodstream upon inhalation. These tiny particles can cause respiratory problems such as bronchitis and aggravate diabetes, heart disease, and other health conditions due to inflammation.

While surface smoke will begin clearing on Wednesday in these regions, high-altitude smoke may persist for much of the week before a new cold front helps clear it out over the weekend. Although high-level smoke has less impact on air quality, it keeps the sky hazy and occasionally makes the sun appear as a brilliant orange, enhancing sunrises and sunsets.

In addition to affecting the East, wildfire smoke is causing air quality concerns in the West, primarily due to homegrown blazes. Large, intense wildfires are currently burning parts of 10 western states, according to the National Interagency Fire Center. Some of these fires emit smoke that travels hundreds of miles away.

California’s Gifford Fire surpassed other wildfires to become the state’s largest of the year on Tuesday, consuming over 82,000 acres across Santa Barbara and San Luis Obispo counties since ignition on Friday and remaining only 7% contained as of Tuesday morning. Evacuation orders have been issued for portions of both counties due to sustained warm, dry conditions and gusty winds that continue to fuel fire growth with minimal aid anticipated from the weather this week.

The Gifford Fire’s smoke dispersed southward and eastward into other parts of Southern California and negatively impacted air quality in certain Nevada regions – including Las Vegas – on Monday. In fact, Las Vegas experienced its worst air quality since February 2023, according to data from the Environmental Protection Agency, with the air quality index peaking at the upper end of the unhealthy – Level 4 of 6 – category early Monday afternoon.

Arizona’s Dragon Bravo Fire is also spreading smoke far eastward as it rages along the North Rim of the Grand Canyon. This megafire, ignited by a lightning strike on July 4th, has become one of Arizona’s largest in history and has destroyed numerous structures, including a historic lodge. Its intensity has created its own weather at times.

Another wildfire generating its own weather and threatening nearby communities is Utah’s Monroe Canyon Fire. It is the state’s largest wildfire of the year, having burned through over 63,000 acres since mid-July. The fire was only 13% contained as of Tuesday morning.

Smoke from the Monroe Canyon Fire and the Dragon Bravo Fire has at times merged and spread into portions of Colorado, Wyoming, and New Mexico.

The wildfire season in the US is far from over, and smoke issues will continue as long as fires persist. The West will remain the primary wildfire hotspot through at least September, according to forecasts from the National Interagency Fire Center.