Almost all living creatures on Earth breathe in some way, even trees and plants. While breathing is something all people have in common, unfortunately we don’t all breathe clean air. Human activity and some natural forces allow toxic materials into our atmosphere, which is the layer of gases that surrounds our planet. This air pollution can threaten our health and quality of life.

The U.S. Environmental Protection Agency (EPA) created a tool called the Air Quality Index (AQI) to inform the public of the level of air pollution and the risks it can pose to our health. Air quality can change very quickly, and the AQI allows people to stay on top of current air conditions in their area, just like the weather forecast.

Below, we’ll discuss how to use the AQI to understand air quality in your community and what you can do to keep you and your loved ones safe when the air quality is poor.

What is air quality?

The average human takes about 22,000 breaths every day, supplying our body with the oxygen it needs to function. Clean, oxygen-rich air is essential for our health, but the air around us can also contain harmful substances, called pollutants. Air quality refers to the level of pollutants in the air.

Good air quality means the air is relatively clean and there are few or no pollutants present that day.

Bad (or poor) air quality means the air contains one or several pollutants in amounts that are hazardous to our lungs and overall health.

Pollution in different forms causes poor air quality

Poor air quality is polluted air, and there are many sources that contribute to air pollution:

Human industry and activity: Our cities, agricultural areas, power plants, factories and oil refineries pump pollutants into the air in the form of smoke, soot and smog. After the 4th of July holiday, the air quality can deteriorate temporarily due to lingering smoke from fireworks.

Transportation: Cars, buses, airplanes, trains and any machine with a combustion engine put pollution into the air through the exhaust they produce.

Nature: The smoke and microscopic matter from wildfires, dust storms and volcanic activity can pollute our air, while air currents and geographic features – like valleys – determine where much of that polluted air concentrates.

Air quality is more of a concern during the summer months when the combination of pollutants in the air and heat creates dangerous conditions.

The impact of wildfires on air quality

Wildfires produce air pollution in the form of smoke. This smoke creates hazy conditions outside, and is full of fine particle matter. This particle matter is small enough to easily penetrate indoor spaces, get into our lungs and even spread to the heart through the cardiovascular system.

These particles are not just from burning organic matter: When wildfires overtake places where people live, the flames burn through manmade materials, like plastic, and spew smoke containing chemical particles that can be especially harmful to our health. On a day with smoky conditions, you might find it harder to breathe while outside and experience chest pain, headaches and irritation in your throat or eyes.

In recent years, wildfires have begun to burn bigger and last longer, covering huge areas of land and raging on for weeks at a time. In 1986, it took an average of less than eight days to contain or extinguish wildfires. In 2013, that average had become 37 days. The duration of wildfire season has also increased – it used to be just four months out of the year, but now extends to six or eight months.

Those most at risk from poor air quality are called “sensitive groups”

Air pollution isn’t good for anyone, but it’s especially bad for the very young and very old, people with certain health conditions, and people who spend a lot of time outside. Those most at risk of experiencing negative health effects in bad air quality are considered “sensitive groups.” This category includes:

  • People who have cardiovascular or lung disease, including asthma, COPD and lung cancer
  • Adults aged 65 and older
  • Children and teenagers
  • Pregnant women
  • People who frequently exercise outside
  • People living in poverty
  • People who smoke tobacco or who live with someone that does
  • People who live and work close to major roadways or industrial areas
  • People who work outside

For some of these groups, it’s not a current health condition that makes them more sensitive to poor air quality, but other ongoing factors that increase their level of risk in air pollution, as well as their vulnerability if they were to develop an illness.

What is the air quality index (AQI)?

In 1970, the EPA established the Clean Air Act, a set of laws that restricts and regulates the amount of pollutants allowed in the air in the United States. The Air Quality Index (AQI) was created soon after. The AQI notifies the public of the air quality around where they live and work, and empowers them to make assessments of the individual health risks involved in venturing outside that day.

The AQI measures the following five pollutants:

  • Airborne particles (solid matter)
  • Ground level ozone
  • Carbon monoxide
  • Sulfur oxide
  • Nitrogen dioxide

Most of these pollutants are invisible to the naked eye, colorless and odorless, and this makes air pollution hard to detect on our own. That’s why these substances are monitored by the EPA, which has determined a safe range for each. When any one of them surpasses their safe range, an air quality alert is triggered.

Image courtesy of the EPA's U.S. air quality index at

What is an air quality alert?

The AQI is divided into five categories, based on the level of pollutants in the air and the corresponding health risk they pose. As a measurement tool, the AQI spans from 0 to 500. An AQI of 50 and below means the air quality is good. The AQI increases with the amount of air pollution to reflect the rising health risk, first for select groups of people, and then for everyone.

An AQI of 200 and above means the amount of pollution in the air has reached dangerous levels for everyone, regardless of their current health or planned outdoor activities.

The Air Quality Index reads as follows:

0-50: Good (green)

The air is clean and clear, and pollutants are mostly absent. It is safe for everyone to be outdoors.

51-100: Moderate (yellow)

There are some pollutants in the air, but they are still within a safe range. However, people with certain health conditions that make them more sensitive to air quality should watch for symptoms.

101-150: Unhealthy for sensitive groups (orange)

One or more pollutants in the air have surpassed their safe range. People in sensitive groups may want to limit outside exercise, while everyone else can continue outdoor activities with caution.

151-200: Unhealthy (red)

People in sensitive groups should avoid extended or vigorous exercise in the outdoors. Everyone else should plan to shorten outdoor exercise or reschedule it for the morning when pollution may be lower.

201-300: Very unhealthy (purple)

Health alerts are triggered. People in sensitive groups should avoid any outdoor exertion. Everyone else should avoid extended or vigorous exercise, and plan to move all activities indoors.

301 and up: Hazardous (maroon)

Everyone should avoid all outdoor activities.

Why air pollution is a health risk

If you spend time outside on a day when the AQI is high, the air pollution can make you feel unwell very quickly, but this is usually temporary. However, breathing polluted air for months or years can result in long-lasting or permanent health impacts. The length of your exposure determines the repercussions to your health.

Short-term exposure to air pollution can cause:

  • Trouble breathing
  • Headaches
  • Dizziness
  • Nausea
  • Nose, throat, eye or skin irritation
  • Recurring pneumonia and bronchitis

Long-term exposure to air pollution can cause:

  • Damage to the cardiovascular system
  • Diminished lung capacity and function, leading to chronic wheezing, coughing and shortness of breath
  • New chronic lung conditions like asthma, emphysema and lung cancer
  • The worsening of existing lung conditions like COPD and asthma, with more frequent asthma attacks
  • A shortened lifespan

What to do when the air quality is bad

If you’re wondering about the air quality where you live or work, go to and enter your city or zip code. It will tell you the current AQI for the area, the forecasted AQI for the next three days and more.

Follow the tips below to stay safe on those days when the air quality is very unhealthy (purple) or hazardous (maroon):

  • Avoid spending any time outdoors and keep children from playing outside
  • Limit activities that cause you to breathe heavily
  • Keep windows and doors closed to prevent outdoor air pollution from spreading through your home or workplace
  • If it’s a hot day, turn on the air conditioner, but only if your AC model has a filter and doesn’t draw from outside air – if you don’t have air conditioning, try to go somewhere that does
  • If you have to go outside, wear a N95, KN95 or P100 mask to protect yourself from inhaling pollutants

Indoor air quality

Good air quality in your home and workplace is just as important to your health and well-being as the air quality outside. In the U.S., we spend a lot of time indoors, so indoor air is the majority of what we breathe. And when the air quality outside is poor, you should be able to have an indoor space where you can safely stay until conditions improve.

Some common sources of indoor air pollution include:

  • Household features and appliances that burn fuel like stovetops, furnaces and fireplaces
  • Biological matter like mold, mildew and bacteria
  • Household products that contain asbestos like insulation, ceiling and floor tiles, roofing shingles and vinyl materials
  • Lead-based paint or pipes
  • Secondhand tobacco smoke
  • Wood furniture or flooring with stains or finishes containing formaldehyde
  • Volatile organic compounds (VOCs) found in carpet, varnishes, glues and adhesives, upholstery, air fresheners and other products

Ways to improve indoor air quality

With so many potential sources, it’s easy to become overwhelmed at the thought of eliminating indoor air pollution. However, knowing there’s a problem is the first step to fixing it. And you can preserve your health and the health of your home by taking just a few steps to clear the air.

  • Address air pollution directly by sealing, enclosing or removing any sources of pollution (including harsh cleaning solutions)
  • Increase indoor ventilation by opening windows whenever possible and using ceiling fans
  • Purchase an air filtering device that continuously pulls in dirty air and emits clean, filtered air
  • Keep your home clean – dust, wipe down and vacuum surfaces often (in that order, to prevent the vacuum from kicking up too much debris) to get rid of dust and other irritants, and opt for cleaning products with natural ingredients, like vinegar.

Considerations for exercising during an air quality alert

Before going outside to exercise, it’s a good idea to check the current AQI, just like you would the weather. If the air quality is poor that day, consider:

  • Your health history and current medical conditions
  • The type, duration and intensity of the exercise you plan to do

Those in sensitive groups can exercise outside when the AQI is 150 or below, but should plan for a short, easy workout and watch for symptoms. People who are not in a sensitive group can exercise outside when the AQI is below 200, but should also keep exertion mild and to a minimum.

Keep in mind that, no matter the AQI level, exercising near busy, congested roadways can expose you to high levels of vehicle emissions. Plan a different route for your run or bike ride that follows mostly residential streets, trails and parks.

Air quality in Minnesota and the Upper Midwest

The air quality across Minnesota has been improving overall since 2003, and much of the Upper Midwest enjoys good air quality for most of the year. However, as wildfires become larger and more frequent in the western United States and Canada, the Upper Midwest is experiencing increasing air pollution in the form of wildfire smoke.

During the wildfire season, which typically runs through the summer and into early fall, wildfire smoke can be carried far from the original site of the fires by air currents. In the case of the Upper Midwest, smoke from Canada travels hundreds of miles on north-south air currents and drastically impacts the air quality in certain areas of Minnesota, Wisconsin, the Dakotas, Michigan and northern Illinois. Air currents change, which means these poor air conditions usually only last a few days. But those few days can put everyone at risk of ill health effects, especially those with existing heart and lung conditions.

Additionally, our increasingly warmer and drier summers both increase incidences of wildfire and allow for higher levels of harmful ozone pollution.

Low-income communities and communities of color in urban areas are disproportionately impacted by air pollution. This is typically the result of proximity to major highways and industrial areas. Air pollution will continue to be a problem until all of us can breathe clean air.

Care to help you breathe easier

It’s important to keep yourself and your loved ones safe during periods of poor air quality for long-term health and well-being. If you have concerns about air quality in your area, talk to your primary care doctor about what you can do to protect your lungs and your overall health.

For more information on air pollution and to get up-to-date air quality conditions in your area, visit