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Air Quality: How is it Measured and How Can You Protect Yourself?

Posted June 28, 2023 by Brian Bauman, M.D. & Aliaksandr Ramaniuk, D.O.

Hazy air

Air quality is measured through the Air Quality Index (AQI). The AQI is an index for reporting daily air quality. It informs you about how clean or polluted the air is in your area and what associated health effects might concern you.

AQI tracks harmful foreign substances, generally gasses and particulates, that have reached harmful levels in the air. AQI runs from 0 to 500; the higher the AQI value, the greater level of air pollution and health concerns. For example, an AQI value of 50 or below means the air quality is good, while an AQI value of 301 or higher means the air quality is hazardous. The chart below outlines the AQI values, levels of concern and description of the air quality.

Air quality chart

Chart source:

The most commonly measured pollutants outdoors are: 

  • Particulate matter (PM): Small solid particles and liquid droplets found in the air. PM10 and PM2.5 refer to particles with a diameter smaller than 10 micrometers and 2.5 micrometers, respectively. It’s derived from motor vehicles, wood heaters and industry. Fires and dust storms can also produce high concentrations of particulate matter.
  • Nitrogen dioxide (NO2): A gas and a major component of central city air pollution. It mainly comes from vehicles, industry, power stations and heating. 
  • Ozone (O3): A gas composed of three oxygen atoms. Ozone is made by a chemical reaction between the sun’s rays, organic gasses and oxides of nitrogen released by:
  • Sulfur dioxide (SO2): A toxic gas with a pungent, irritating odor. It can come from electric industries that burn fossil fuels, petrol refineries and cement manufacturing.
  • Carbon monoxide (CO): A gas from motor vehicles or machinery that burn fossil fuels. 

Reduced air quality can exacerbate underlying lung diseases, particularly asthma and COPD. Those with underlying lung disease should use caution and potentially limit outdoor activities while air quality is affected. Depending upon the AQI value, it can also be dangerous for even the healthiest individuals.

Signs of worsened breathing may include:

  • Increased shortness of breath
  • Low oxygen levels
  • Wheezing
  • Chest tightness
  • Cough

Should you notice that your breathing seems to be significantly worsened due to reduced air quality, we recommend:

  • Talking with your healthcare provider about an action plan for respiratory symptoms
  • Asking about a peak flow meter
  • Having your rescue inhaler at hand
  • Checking to see if you have a nebulizer at home for breathing treatments
  • Calling your healthcare provider if your wheezing or shortness of breath gets worse
  • Going to the emergency room if your symptoms become severe

To help keep you and others safe, please be aware of the daily AQI that will let you know when high pollution days are so you know when to take steps to protect yourself.

You can protect yourself from air pollution and poor air quality by:

  • Adjusting your plans – avoid prolonged outdoor activities and high-traffic areas
  • Wearing a mask outdoors – an N95 mask is the best protection. A surgical mask is approximately 60 percent effective. Cloth, scarves and gators are less effective.
  • Staying indoors when the AQI is higher than 200 and you’re having breathing problems
  • Keeping car windows up and house windows closed
  • Limiting outdoor activities and exercises


Options to Request an Appointment

If your situation is an emergency, call 911.