Why air quality is worse when it's really hot

Record-breaking high temperatures have enveloped much of the U.S., causing at least five deaths in Portland, Ore., and Death Valley, Calif., in recent days.

Those exposed to the oppressive temperatures and the dangers they bring may also experience shortness of breath or a burning sensation in their nose or eyes, as recent excessive heat warnings have been paired with air quality alerts in many parts of the country. Why is that?

Yahoo News spoke to air quality experts who explained how heat waves, which are happening more often and lasting longer recently, can lead to poor air quality — and what that can mean for your health.

What is the connection between air quality and extreme heat?

Marianthi-Anna Kioumourtzoglou, an associate professor of environmental health sciences at Columbia University's Mailman School of Public Health, told Yahoo News in May that sunlight creates a type of air pollution, called ozone, made up of toxic gas created in the Earth’s atmosphere.

While a concentration of ozone is typically a summertime issue, it can be exacerbated on particularly hot days with low wind speed.

"The pollution can stay over a city," Kioumourtzoglou said.

"The summertime conditions, where it's hot and there's a lot of sunlight, kind of push that chemistry to go faster and make more ozone," Peter DeCarlo, associate professor of environmental health and engineering at Johns Hopkins University, explained to Yahoo News in May.

Additionally, drought conditions can worsen air quality by triggering wildfires. According to the University Corporation of Atmospheric Research — a nonprofit group of colleges and universities that provide research and training in atmospheric sciences — these fires release carbon monoxide and particle pollution into the Earth’s atmosphere.

“Wildfires are a significant contributor to air pollution,” Glory Dolphin Hammes, CEO of IQAir, a technology company that monitors air quality for the United Nations, told Yahoo News Tuesday. “With climate change, we have more often these drought conditions than previously because of the fact that the Earth is getting warmer.”

How can you monitor the air quality in your area?

The U.S. has a measurement system for air quality called the air quality index (AQI). The AQI has six color-coded categories with a value system that runs from zero to 500. The higher the level of air pollution the more hazardous it is for your health. You can find the current AQI for your area by typing in your zip code at AirNow.gov.

“There are different categorizations of air quality from good to moderate to unhealthy for sensitive groups to unhealthy for pretty much everyone, and then progressively worse beyond that,” DeCarlo said.

State environmental agencies have about 4,000 monitoring stations that are regulated by the Environmental Protection Agency (EPA). The stations send hourly or daily measurements of the following air pollutants to the EPA's database, called the Air Quality System:

• Ground-level ozone

• Particulate matter

• Carbon monoxide

• Sulfur dioxide

• Nitrogen dioxide

When particulate matter — defined by the EPA as “a mixture of solid particles and liquid droplets found in the air” — reaches unhealthy levels for the public, it triggers an air quality alert on most smartphones.

Can poor air quality exacerbate the effects of extreme heat?

Experts say that air pollution can be pretty toxic for your health. It has been linked to adverse cardiovascular, pregnancy and neurodevelopmental outcomes. When you breathe in air pollution, the particles can produce an imbalance in the body known as oxidative stress, and can cause inflammation in your lungs that triggers wheezing, shortness of breath and tightness in the chest.

“Both inflammation and oxidative stress are harmful to the body,” Kioumourtzoglou said. “That's why air pollution has the potential to impact all our organs and all our systems.”

Hammes offered suggestions for staying safe from air pollution on extremely hot summer days, including limiting outdoor activities, wearing a properly sealed N95 mask, using an air purifier and running an air conditioning unit indoors.