Topline
Here’s how to understand the Environmental Protection Agency’s Air quality index (AQI), which measures, on a 300-point scale (along with six categories and advisories), the quality of air in any given area based on the amount of air pollutants present and the risks they pose to public health.
Smoke from Canadian wildfires has raised the Air Quality Index of many Northeastern cities. (Photo … [+]
Key Facts
0-50 AQI: Indicated by the color green, at this rate, the EPA says air pollutants that are present pose no risk.
51-100: Moderate air quality (color: yellow), and the EPA reported in 2014 that the AQI for most U.S. communities is under 100 (Still: Those who are impacted by coughing or breathing troubles are advised to shorten their time outside and do less intense activities).
101-150: Air quality is deemed unhealthy when it’s over 100 (color: orange), and particularly sensitive groups—seniors, those with pre-existing conditions like heart and lung disease, people with asthma, minorities, outdoor workers or those who are usually active outside such as children and teenagers are particularly vulnerable—should proceed with caution by shortening time spent outdoors, and tracking symptoms of fatigue or breathing issues for those with heart disease.
151-200: Over 150 (color: red), the air is deemed unhealthy for most, and people are advised to reduce long, intense outdoor activity, with sensitive groups advised to either avoid outdoor activities altogether or do them in the morning.
201-300: Above 200 is considered very unhealthy (color: purple) and the air quality becomes unhealthy for everyone, with people typically being advised to completely avoid doing lengthy, intense physical activities outdoors and to stay indoors.
300 OR HIGHER: At this point, the air is considered hazardous (color: maroon), officials will issue health emergency warnings, and everyone is advised to stay inside—including schools, which should move all activities indoors.
When Do Schools Close Because Of Air Quality?
Most states don’t have air-quality guidelines that require schools to be closed, but the EPA has clear guidelines on student activities—with no outdoor activities advised when the AQI passes 300. Many schools throughout the Northeast have limited outdoor activities and canceled recess because of the recent wildfires in Canada and its impact on air quality in the region.
Key Pollutants: Particulate Matter, Ozone
Particulate matter, or PM for short, is particle pollution that is typically found in smoke and sourced from wildfires, according to IQAir. The National Weather Service reports that “chronic bronchitis, asthma attacks, decreased lung function, coughing, painful breathing, cardiac problems and heart attacks” are all health risks of particle pollution exposure. As of 2021, guidelines from the World Health Organization made 15 μg/m3 the ceiling for particle matter over a 24-hour level compared to 25 μg/m3 in 2005.
Tropospheric ozone, or the ground-level ozone that is consumed each day, is responsible for smog, with higher concentrations being common throughout the summer or hotter months. Health risks related to ozone include irritable respiratory systems noted by coughing or chest pains and tightness, reduced lung function or aggravation that makes the lungs more susceptible to infection and can even cause permanent lung damage, according to the EPA. When the ozone is at its highest concentration, WHO’s standards for ozone are set at 60 μg/m3.
Key Background
Last year, IQAir recorded 37 as the average AQI in the United States, with the most polluted city, Arch Cape, Oregon, having a 96. Today, cities across the northeast region are surpassing the AQI 300 threshold. Six of the country’s top 10 polluted cities—including the top three—are in Pennsylvania. The top three are at maroon levels. The National Weather Service has issued air quality alerts for much of the Northeast and some midwestern states and southern urban areas.
Source: https://www.forbes.com/sites/darreonnadavis/2023/06/08/what-the-air-quality-index-means-and-when-you-should-stay-inside/