As of October 19, 2021, 17 wildfires are burning in California, Idaho, Montana, Oregon, and Washington. Only two of these are contained, and all 17 have collectively burned more than 2.2 million acres (about 3,400 square miles). So far this year, over 47,000 fires have burned about 6.5 million acres (just over 10,000 square miles) in the U.S. (1)

The yearly prevalence of wildfires often leads to a larger conversation about outdoor air quality monitoring generally, including concerns about smoke, smog, ozone, carbon monoxide, and other air pollutants that negatively affect the health of living things. (1, 2)

The Environmental Protection Agency (EPA) monitors and regulates both ambient air pollution and stationary sources of pollution in the U.S. However, there is much you can do to help improve air quality, as well. Taking even a few of the suggested measures can improve the air quality in your home and environment over time, which can lead to improved overall health for you and your family.

Air Pollutants

The following are the major contributors to air pollution and constitute serious threats to human health:

• Wildfire smoke. Wildfire smoke contains thousands of chemicals that can cause severe respiratory issues, chest pain, and a fast heart rate. Children, the elderly, first responders, and pregnant women are particularly at risk for serious consequences from inhalation. Compounding the risk is the fact that wildfire smoke ages - meaning that the sun acts on it and other chemicals in the air - as it travels, increasing its toxicity. Large particles like ash typically do not travel far from the fire, but aerosolized smaller particles can travel across continents. These smaller particles, which are less than 2.5 micrometers in diameter (50 times smaller than a grain of rice), are collectively called particulate matter. They are small enough to bypass the body's natural defenses, enter the lungs, and cause respiratory problems like lung inflammation. (3, 4)
• Smog. Comprising many chemicals, smog is air pollution that reduces visibility. The term comes from the Industrial Revolution when smoke from burning coal mixed with fog relatively close to the ground and created a yellowish-brown haze. There are two types of smog: normal and photochemical. Normal smog results from burning high-sulfur coal, whereas photochemical smog is formed when sunlight reacts with nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the atmosphere. (5, 6) VOCs are compounds that have a high vapor pressure and low water solubility. Many VOCs are human-made chemicals used and produced in the manufacture of paints, pharmaceuticals, and refrigerants. (7)

Both wildfire smoke and smog can contain any combination of the following six:

1. Carbon monoxide (CO). CO is a poisonous, colorless, odorless, tasteless gas that is deadly in high concentrations. CO is released from burning materials containing carbon, like gasoline, propane, and natural gas. By displacing oxygen in the blood, CO deprives vital organs of oxygen. Exposure to large amounts or high concentrations of CO can cause death in minutes. Even if a person with CO poisoning is rescued and survives, he or she may have permanent neurological and heart damage. Age and general health also play a role in a survivor's prognosis. (8, 9)
2. Nitrogen oxides (NOx). A mixture of gases containing nitrogen and oxygen, nitrogen oxides are released to the air mainly from motor vehicle exhaust, as well as burning coal and natural gas. Nitrogen oxides are used in the production of rocket fuel and explosives, among other things. (10)
3. Ground-level ozone (O3). Tropospheric or ground-level ozone forms when the pollutants from motor vehicles, oil refineries, power plants, and chemical plants react with sunlight. Ground-level ozone contains NOx and VOCs. (11, 12)
4. Particulate matter (PM). PM refers to solid and liquid particles in the air, some of which can be seen with the naked eye. Others can only be detected with an electron microscope. Some come directly from certain sources, such as construction sites, unpaved roads, fields, or fires, but most are the result of complex chemical reactions of power plant, industrial, and automobile pollutants. (13)
5. Sulfur dioxide (SO2). Sulfur dioxide is a colorless gas with a pungent, rotten-egg odor. In nature, it is released into the atmosphere from volcanic eruptions. It also enters the atmosphere through burning coal and oil and from copper smelting. (14)
6. Lead (Pb). A bluish-gray metal found in all parts of the environment, lead comes from burning fossil fuels, manufacturing, battery production, and devices that shield people from