Smoking Wildfires in Canada Has drifted to the United States, prompt Air quality The alarm is when Americans continue to spread.

But what exactly does this mean when officials and forecasters classify the air in a city as “unhealthy” or “dangerous”? The classification is based on a federal measurement system called the Air Quality Index.

What is the air quality index?

The Air Quality Index is used nationwide to measure the severity of air pollution and will be classified with health risks at various levels of pollution. The index uses six color coating categories: Good (green), Moderate (yellow), Sensitive Group (Orange), Unhealthy (red), Very Unhealthy (Purple) and Dangerous (Maroon) (Maroon).

The health effects included in the index are those that people may experience in "hours or days" after exposure to the air, the National Weather Service said.

How to measure air quality?

The National Meteorological Administration said the Environmental Protection Agency calculated the air quality index (between 0 and 500) based on five "main pollutants." These pollutants - ground ozone, particulate matter, carbon monoxide, sulfur dioxide and nitrogen dioxide - are all regulated by the Clean Air Act. Among them, ground ozone and airborne particles are considered "the greatest threat to human health."

What does numbers mean?

Each air quality index category (also known as the degree of concern) is attached to a certain range:

• Good (green): 0 to 50
• Medium (yellow): 51 to 100
• Unhealthy (orange): 101 to 150
• Unhealthy (red): 151 to 200
• Very unhealthy (purple): 201 to 300
• Danger (MARRON): 301 and higher

Essentially, the lower the quantity, the cleaner the air is. The only category that considers air quality to be "satisfactory" is the category that has an index value of no more than 50, although values ​​between 51 and 100 are still considered "acceptable". After that, air may pose a risk to at least some people, and this risk will only become greater as the index value rises.

Once the air is considered “very unhealthy”, the public has the risk of experiencing it Health Impactsranging from headaches and fatigue to more serious problems such as heart attacks or strokes. At the “hazardous” level, the region is in an air quality emergency. People with chronic respiratory or cardiovascular disease are more susceptible to serious health problems with worsening contamination.

What is the air quality near me?

As weather conditions and weather patterns develop in the region, the value of the air quality index continues to change. airnow.gov uses this index to provide the latest status for your region. To use the site, enter your postal code and pop up the meter to show you the value and color categories of your city and the last updated measurement.

It also tells you which pollutants are causing the problem, who is most at risk of health complications and which activities may be safe.

For example, in Minneapolis, Aqi on Tuesday morning said the AQI of PM2.5 is a particulate matter, which is 203, meaning “very unhealthy” that people with heart or lung diseases, older people, as well as children and adolescents should avoid Outdoor physical exercise. In this case, everyone else should avoid "severe" and long outdoor activities.