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Here’s What You Need To Know About The Air Quality Index (AQI)

What is the Air Quality Index (AQI)?

The Air Quality Index (AQI) was implemented in 1968 by the National Air Pollution Control Administration to give officials the tools to calculate pollutants in the air, evaluate health risks posed by those pollutants, and let the public know how safe it is to breathe that air.

The AQI in the U.S. is now managed by the Environmental Protection Agency (EPA). They constantly measure five major air pollutants: ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide and particulate matter. Whichever pollutant of those five measures highest is used to determine the current AQI. 

What are the different levels of the Air Quality Index?

The AQI consists of six levels: Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy and Hazardous.

  • When the AQI is 0-50, or “Good,” it’s safe for anyone to be outside.
  • When the AQI is 51-100, or “Moderate,” most people can safely be outside, but people who are especially sensitive to pollutants should remain indoors.
  • When the AQI is 101-150, or “Unhealthy for Sensitive Groups,” people at higher risk, including the elderly, young children or anyone with underlying heart or lung issues, should limit the time they spend outdoors.
  • When the AQI is 151-200, or “Unhealthy,” sensitive groups should remain indoors, and everyone else should limit prolonged or heavy exertion outdoors as much as possible.
  • When the AQI is 201-300, or “Very Unhealthy,” everyone should remain indoors as much as possible, including healthy people.
  • And when the AQI is above 301, or “Hazardous,” everyone should remain indoors until the AQI improves.

It’s important to take the appropriate precautions based on your age and underlying health conditions.  And it’s also wise to seek urgent medical attention if you develop any concerning symptoms, since early intervention in serious health conditions often leads to a better outcome.

How do wildfires affect the Air Quality Index?

Due to the current wildfires affecting many states in the western U.S., the air pollutant measuring the highest right now is called PM2.5. PM stands for “Particulate Matter” and 2.5 refers to the size of the particles, which is 2.5 micrometers. 

Because 2.5 micrometer particles are tiny (about 3% of the diameter of a human hair), they are particularly dangerous because they can deposit deeper in lung tissue than larger particles can.  This can cause damage to anyone’s lungs, and it can trigger an exacerbation of underlying lung conditions, including COPD and asthma. PM2.5 particles can also seep into the bloodstream and cause damage to other organs, including the heart.

We know from studies done during the wildfires in Australia earlier this year that a high level of PM2.5 particles correlates with a surge in 911 calls and E.R. visits for patients experiencing cardiopulmonary symptoms, including shortness of breath, wheezing, dizziness, chest pain, palpitations and weakness. 

If you live in an area affected by the wildfires, it’s important to frequently monitor the AQI in your area, and follow the guidelines it suggests.


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