Air: Outdoor Air Quality and Health

Outdoor air pollution comes from both human activities and natural sources. The burning of natural gas, coal, biomass, and wood for energy, and petroleum for transportation cause air pollution.

Wildfires or weather patterns, like heat waves, can also contribute to unsafe air pollution. Climate change will increase the frequency of wildfires and the weather patterns that increase heat, humidity, and air pollution.

In Wisconsin, we’re most concerned about health risks from two types of air pollution.

• Ground-level ozone, sometimes called smog, and
• Fine particles under 2.5 microns, called particulate matter or PM2.5.

Ground-level ozone, sometimes called smog, is a harmful air pollutant that causes health issues like trouble breathing and heart problems. It can even lead to death. Ozone forms when gases released from cars, smokestacks, and other sources combine with sunlight and heat.

In Wisconsin, we are most concerned about ozone during the warmer summer months because sunlight and hot temperatures are needed for ozone to form. Ozone doesn’t just stay in one place, but can be carried by the wind far from its source. This means ozone is not just a local problem, but a regional, national, and even international health issue.

When we breathe in ozone in the air, it can harm our health even at relatively low levels. Depending on the frequency and level of exposure, ozone can cause:

The areas in Wisconsin most often impacted by unhealthy ozone levels are the counties in the southeastern part of the state along the shores of Lake Michigan, from Kenosha County up to Door County. On average, those counties exceed the national ozone standards, called NAAQS (National Ambient Air Quality Standards). Elevated ozone levels can also affect air quality across the entire state at times.

For more information, visit Environmental Protection Agency's (EPA) webpage on ground-level ozone pollution (opens external link).

Particle pollution, also called particulate matter (PM), is a mixture of particles (tiny pieces) of solids and liquids in the air, such as ash, vehicle exhaust, and soil dust. These particles come in different sizes, from larger, course particles, to smaller, fine and ultrafine particles. Fine particles that are less than 2.5 microns in diameter are called PM2.5.

These tiny particles are most dangerous to our health. They are so small that they get trapped in the body when they're breathed in, instead of being sneezed or coughed out like larger particles. Tiny particles can even get into your bloodstream. Exposure to PM2.5 can lead to new or worsened heart and lung diseases, cancers, and even death. Health effects include:

Like ground-level ozone, particle pollution forms from vehicle emissions, power plants (coal, natural gas, biomass), some industrial facilities, smoke from wildfires and wood burning (campfires, outdoor wood boilers and stoves), soot, pollens, dust, soil, and other sources. However, unlike ozone, PM2.5 is a health concern in Wisconsin year-round, because it doesn’t require sunlight or warm temperatures to form. Learn more about particle pollution from the CDC (Centers for Disease Control and Prevention).

Climate change creates conditions that lead to increased levels of ground-level ozone and particle pollution. Increased temperatures, decreased precipitation, and changing wind patterns caused by climate change make it easier for ozone and particle pollution to form. Stagnant (non-moving) air and hotter weather make higher levels of ozone more likely, while hotter temperatures and lack of rainfall can lead to increased drought and wildfires, both of which cause particle pollution.

Warmer temperatures due to climate change also mean longer growing seasons, leading to increased pollen in the air. These allergens cause health problems and irritations for many people with allergies. When sensitive populations, such as those with asthma or other respiratory illnesses, are exposed to both pollen and air pollution at the same time, asthma attacks and allergic reactions can be more severe.

Air pollution also contributes to climate change. Greenhouse gases, such as carbon dioxide and methane, are released from the same human activities that create high levels of ozone and particle pollution. These heat-trapping gases cause increased global temperatures, the root cause of climate change, which continues the cycle of increased ozone and particle pollution that harm our health.

For more information, visit EPA's Climate Change Impacts on Air Quality webpage. (opens external link)

Anyone’s health can be affected by unsafe air quality, but certain groups are more at risk of health harms than others. People with existing health problems, such as asthma or other lung and heart diseases—are at greater risk of harmful health outcomes from air pollution.

Additionally, children, older adults, pregnant adults, and people who live or work outdoors for long periods of time or participate in intense exercise outdoors are more at risk of health issues from air pollution. Children are at greatest risk from exposure to air pollution because their lungs are still developing and they're more likely to be be active outdoors when pollutants like ozone are high. As a result, kids are breathing in more pollution than adults, pound for pound. Children are also more likely than adults to have asthma.

There are also racial, ethnic, and income disparities in air pollution exposure. Due to environmental injustice and systemic racism, low-income communities and communities of color are more likely to live near more sources of air pollution and unhealthy air quality, and therefore face more negative health outcomes than higher income, white populations. These communities also face higher rates of heart and lung conditions due to existing health inequities, placing them at greater risk of health harms from air pollution. These groups also breathe in far more air pollution than is created by their activities.

Even if you don't live near an active wildfire, the wind can carry thick wildfire smoke thousands of miles from the source and make the air unsafe to breathe. Wildfire smoke is a mix of gases and tiny particles from burning trees and vegetation, and other synthetic materials and heavy metals. Wildfires spread other harmful emissions in smoke, including nitrogen oxides (opens external link) and many hazardous air pollutants (opens external link), when they spread to communities and burn structures, cars, plastics, and other materials.

Carbon monoxide (opens external link), a colorless, odorless gas, also commonly forms near smoldering fires. It can lead to headaches, nausea, dizziness and, in high concentrations, even premature death.

Wildfire smoke can make anyone sick. Even someone who is healthy can get sick if there is enough smoke in the air. Older adults, pregnant adults, children, and people with chronic breathing and heart conditions may be more likely to get sick if they breathe in wildfire smoke. Breathing in smoke can have immediate health effects, including:

Studies also show that long-term exposures to particle pollution contribute to premature deaths. However, the long-term health effects of wildfire smoke exposure are not well studied because of the complex mixture of pollutants. There are studies currently underway to improve understanding of longer term health harms from wildfire smoke exposures.

The Air Quality Index (AQI) from the EPA (opens external link) is a tool used to report daily air quality by sharing how clean or polluted the air is. It serves as a warning system for the public when air pollution reaches unhealthy levels. Weather apps, and radio, TV, and online news outlets all report daily weather forecasts and AQI levels. Checking these sources regularly can help you to know if you need to take steps to avoid unhealthy outdoor air.

The Wisconsin Department of Natural Resources (DNR) issues air quality health advisories when air quality is in the orange range for people who are sensitive to air pollution or in the higher red, purple, and maroon zones when air is unsafe for everyone. Here's how you can find out if an air quality advisory has been issued in your county:

• Sign up to receive statewide air quality notices (opens external link) for your county (opens external link) via email or text from the Wisconsin Department of Natural Resources (DNR).
• Visit DNR's Interactive Air Quality Map (opens external link) that displays current air quality for each county.
• Visit airnow.gov (opens external link) to check your local air quality.

Air Quality Index

Good
0-50

Moderate
51-100

Unhealthy for Sensitive Groups
101-150

Unhealthy
151-200

Very Unhealthy
201-300

Hazardous
301-500

When the day’s air quality is forecasted to be in your unsafe zone—orange or worse—make a plan to protect yourself and your loved ones. First, follow guidance provided by your local health department and other health officials if an advisory is issued. Here are additional tips you and your family can take to minimize dangers from outdoor air pollution:

1. Sign up to receive DNR air quality notices via text or email or check air pollution forecasts at airnow.gov (opens external link) before heading outdoors.
2. Stay inside with windows closed on high pollution days if possible. Call 211 to find an air conditioned space near you if it's too hot in your home.
3. Take it easy if you have to be outside on orange or higher days, and limit outdoor playtime for kids if the air quality is unhealthy.
4. Encourage schools, daycares, and camps to keep kids indoors on high-pollution days and advocate for school buses powered by cleaner fuels.
5. Follow your asthma action plan if you have asthma and take medications as prescribed. Always have your quick-relief inhaler and spacer with you. Make sure your school or daycare has your child's asthma action plan on file and quick-reliever medications on hand if you child isn't able to self-administer it.
6. Take frequent indoor breaks and avoid strenuous activities if you live or work outdoors.
7. Consider wearing a N95 mask if particle pollution levels are elevated. Keep in mind that no masks can filter out ground-level ozone pollution, so stay inside on high ozone days as much as possible.
8. Move exercise indoors to a gym or shopping mall during the day. Exercise or play outside early or late in the day since ozone levels peak in the late afternoon to evening.
9. Protect your indoor air quality too. Use an indoor air cleaner or homemade air purifier (opens external link) when outdoor air quality is unsafe.
10. Never burn wood, brush, or trash if you live near neighbors or burn on days with high winds or elevated air pollution levels.

There are many steps you can take as an individual or community to improve air quality:

• Choose greener or active transportation. Telecommute, bus, carpool, bike, or walk. Start small—drive or bus part way, then walk or bike to your destination. Try an electric bike or scooter. Advocate for community designs that make biking and walking pleasant and safe.
• Drive your car less. Vehicle exhaust, especially diesel, is a major source of air pollution in Wisconsin. Reduce driving and combine errands when possible. If you're waiting more than 10 seconds, turn off your engine to save gas and reduce air pollution.
• Stay on top of car repairs. Fix exhaust and oxygen sensor problems promptly. Check your tire pressure monthly—under-inflated tires lower your gas mileage, especially at lower speeds.
• Avoid motorcycles and mopeds (or go electric). They don't have pollution controls like vehicles do, so buying electric will help reduce air pollution.
• Switch to electric vehicles. If you live in an area with an electric utility that has a high percentage of clean energy or have solar, consider switching to an electric vehicle and charge at home. Also encourage your schools and city or regional transit to invest in electric buses too.
• Find a car- or bike-sharing service in your area. See if you can get by with fewer cars or none at all.
• Switch to electric or hand-powered lawn equipment. Gas-powered engines like those on lawnmowers and leaf or snow blowers often lack pollution control devices.
• Delay using gas-powered equipment till evening. Wait until it cools off to use gas-powered equipment, fill your vehicle's gas tank, or charge your electric vehicle.
• Use less energy. Conserve electricity—choose energy efficient appliances and heating systems. Get an energy audit and make recommended upgrades. In summer, set your air conditioner at higher temperatures or turn it off and use a fan. In winter, set your furnace lower and bundle up.
• Plant and maintain shade trees. Trees cool your home, improve mental health, filter pollution, and absorb carbon dioxide. Trees also release oxygen into the air. Fruit trees provide shade, nutritious food, and save on grocery bills seasonally.
• Limit backyard fires in town. Minimize the use of wood burning fireplaces, stoves, boilers, and outdoor fire pits and grills. Smoke from backyard fires and wood-burning furnaces can cause serious health problems for neighbors, especially those with asthma and other lung and heart conditions. If you do have a fire:
  • Keep them brief and small.
  • Burn only dry fire wood and never garbage.
  • Never start fires when an air quality health advisory is in effect.
• Become a champion for clean air. Engage kids and teens, neighbors, friends, and coworkers on the benefits of sustainability and pollution reduction. Encourage local government, schools, and businesses to cut their energy usage and air emissions. Direct them to the following programs that provide a framework to help reduce pollution and save money at the same time:
  • Wisconsin Local Government Climate Coalition (opens external link)
  • Urban Sustainability Directors Network (opens external link)
  • DNR Green Tier Legacy Communities (opens external link)
  • DNR Green Tier for businesses (opens external link)
  • DNR Wisconsin Small Business Environmental Assistance Program (opens external link)
  • Wisconsin Sustainable Business Council (opens external link)
  • Health Care Without Harm (opens external link) and Health Care Climate Challenge (opens external link)

Find more ways to reduce air pollution and greenhouse gas emissions, (opens external link) so everyone can breathe easier.