Everyone knows that red means danger, but how did purple become a cautionary color? At an EPA conference in the late 1990s, attendees nearly came to blows over color coding on the Air Quality Index.

So it's also the color on the government chart showing the air quality index is more than 150, meaning unhealthy. When it's more than 200, it's purple, very unhealthy. This makes sense to ...

The Air Quality Index is used nationwide to measure the severity of air pollution and categorize the health risks that are involved with various levels of pollution. ... (purple): 201 to 300 ; ...

The U.S. has one of the world’s most advanced systems to monitor air pollutants. Can it keep up with a changing climate?

The AQI, or air quality index, is a number that measures several aspects of air quality: Particle pollution , both coarse particles (10 microns or less) and fine particles (2.5 microns or less).

The Southwest Ohio Air Quality Agency reports that "levels of ozone within the region may approach or exceed unhealthy ...

As smoke from Canadian wildfires has made its way into the U.S., it is important to understand how the air quality index works. Here's what each color code means.

What is a "Code Red" air quality alert and how it impacts you 02:17. PHILADELPHIA (CBS) -- Air Quality Index (AQI) refers to the Environmental Protection Agency's scale regarding the health impact ...

The EPA's Air Quality Index can tell you whether breathing outside air can hurt you. ... Purple indicates very unhealthy air (151-200) Maroon indicates hazardous air (301 plus).

What the Air Quality Index measures—and what to do when it’s code red. As wildfire smoke from Canada descends on the northeastern U.S., ... In the purple range, 201 to 300, ...

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 ...

The national average air quality index in 2023 was 38, according to IQAir, a Swiss air quality technology company. More than 100 nations had cleaner air , on average, than the United States, and ...