Mountain West News Bureau

Heat and wildfires have worsened air quality across parts of the West

Nevada Public Radio | By Yvette Fernandez

Published July 21, 2026 at 5:00 AM MDT

A map of the United States color coded for air quality. A significant amount of the country is labeled yellow, with some areas orange and a few small areas in the Pacific Northwest red or purple. — A real-time air quality map of the United States on Monday, July 20, 2026. Yellow indicates a "moderate" air quality index, with darker colors representing worsening air quality.

A combination of Western wildfires and summer heat is contributing to health concerns surrounding heat and air quality.

The extreme heat is accelerating chemical reactions that produce harmful ozone, a problem for many major metro areas. With the particulate matter from wildfires, known as PM2.5 and PM10, it's a harmful combination for people's health, according to the U.S. Environmental Protection Agency.

Jodi Bechtel with the Clark County Department of Environment and Sustainability, which includes Las Vegas, Nevada, says stagnant air can contribute to problems.

"The more stagnant it is, the more the pollutants just build up because there's no way for that pollutant to disperse into the atmosphere and no wind to blow it out," she said.

According to AirNow, the federal government's air quality tracker, large most of Utah has been blanketed by "moderate" risk wildfire smoke as of Monday . Part of the state and some nearby states are considered unhealthy for sensitive groups, such as those with chronic heart or lung conditions.

In Nevada, officials issued a season-long advisory for ground-level ozone pollution and wildfire smoke, telling people to stay informed about air quality conditions to protect themselves.

According to the Clark County Department of Environment and Sustainability:

Ozone is a major component of smog. It is formed when pollutants from vehicles, power plants, and industry react in the presence of sunlight and heat. This is why it is a summertime pollutant.
Particulate matter is a mixture of microscopic solid particles and liquid droplets suspended in air (dust, dirt, soot, and smoke). PM10 is 10 micrometers or smaller. PM2.5 are 2.5 micrometers or smaller, making them highly respirable.
Wildfire smoke contributes PM10 and PM2.5 to the air. It can also contribute to nitrogen oxides and volatile organic compounds, depending on the fire fuel.
Heat also affects air quality. In addition to sunlight exacerbating ozone, high pressure systems across the west can cause a dome that causes warm air to become trapped. The high-pressure forces rising warm air back toward the ground, which compresses as it sinks and releases more heat.
Heat causes ground to lose moisture, creating further warming, exacerbating drought conditions and increasing the likelihood of wildfires. The high-pressure dome also prevents clouds from entering, which would help to cool temperatures. Because the air is stagnant, pollutants can build up to unhealthy levels.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Northern Colorado, KANW in New Mexico, Colorado Public Radio, KJZZ in Arizona, and NPR, with additional support from affiliate newsrooms across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.