Here’s the Thing About That Color-Coded Air Quality Index

"Safe" levels of air pollution are unhealthy for many people new research shows. The EPA could change that.

Gray and yellowish smoke limits visibility in photo.
A Circle Line ferry sails past the Williamsburg Bridge as the Manhattan skyline is shrouded in smoke from Canada wildfires on June 6, 2023 in New York City. New York City is bathed in a blanket of unhealthy air as smoke from Canadian wildfires seeps across much of the eastern U.S. and Great Lakes areas. (NDZ/STAR MAX/IPx via AP)

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Bad air quality is the world’s leading environmental killer. In the United States, air pollution is associated with 100,000 to 200,000 deaths each year.

Much of this pollution comes from burning fossil fuels and from industrial sources. It can be suddenly made much worse by wildfire smoke as we are seeing this month with Canadian smoke blanketing the East Coast. Climate change has made these fires worse and more frequent.

We can make big improvements in public health with tighter government standards based on the latest science. Periodically, the Environmental Protection Agency reconsiders its air quality standards and proposes new ones. We are in one of those moments, and you can play a role helping us push the agency to make bold progress.

You may be familiar with the color-coded Air Quality Index, or AQI. A “green” air day represents healthy air quality, while a “purple” air day means to stay inside if you can. Recent years of climate-driven wildfires have sent toxic wildfire smoke across a wider swathe of the country, introducing many to air quality websites like PurpleAir and AirNow.

But air quality that gets marked “green” may not actually be as safe as advertised.

The color and the associated AQI number reflect where the Environmental Protection Agency sets legal standards for five different air pollutants. When the EPA sets these standards, called “National Ambient Air Quality Standards,” it must base them exclusively on what is necessary to protect public health – including the health of those who may be more sensitive to air pollution, people like children, people with heart or lung problems, and older adults — with an adequate margin of safety.  As scientists learn more about the dangers of various air pollutants, those standards look more and more inadequate for protecting our health.

This is a big moment

On Jan. 6, the EPA proposed new standards for PM2.5 — a short-hand for particulate matter involving small particles the diameter of 2.5 microns or less. It’s also commonly referred to as soot.

“With PM 2.5, the EPA knows that kills people,” says Seth Johnson, a senior attorney at Earthjustice. “And for PM 2.5, the evidence of disparate impact is really strong. We know it affects people of color — particularly Black people — at least in part due to differences in exposure.” Latino people also experience elevated exposure.

When people breathe in PM2.5, the particulate matter inflames the airways, gets into the bloodstream, and impairs the body’s immune responses. Exposure is linked to increased rates of a dizzying array of complications including heart attacks, strokes, lung cancer, and Alzheimer’s disease.

Unfortunately, the government’s January proposal is “a disappointment and a missed opportunity overall,” says Johnson. The current standards are set at an annual level of 12 micrograms per cubic meter (mcg/m3) and daily level of 35 mcg/m3. The EPA proposed to strengthen the annual standard to 9 or 10 mcg/m3 but leave the daily level unchanged.

The EPA has also been slowly working on a new proposal for another widespread, harmful pollutant — ozone smog. But the agency’s timeline has slipped. Community and health groups have been calling on the agency to move quickly to strengthen this standard, too.

Though aspects of the EPA’s PM2.5 proposal would somewhat strengthen protections, impacted communities and the nation’s leading health and medical groups have consistently called for stronger standards than what the agency has proposed. EPA’s independent expert science advisors also recommended standards stronger than what the agency has proposed.

“The EPA could save nearly 20,000 lives with stricter protections,” says Johnson. “We urge the EPA to hear communities, not industrial polluters, and strengthen this rule. Overburdened communities have the right to breathe clean air.”

How standards save lives

Here’s how a better government standard would make a difference to your air.

When an industrial polluter wants to open a new facility, it must apply for air permits. Those permits will only be given if the operator can show that the added pollution won’t tip the region’s air quality over the legal limits.

And if a region’s current air quality is worse than a newly tightened standard, state governments must draw up and execute plans to curb air pollution so that air quality will meet the updated standard. For PM 2.5, such a plan could involve cutting car traffic by improving public transit or instituting carpool lanes. Or, if there are some industrial facilities like coal plants that do not have modern scrubbing technology, the state can compel them to clean up.

Earthjustice watches to make sure that the governments put forward real plans and follow through on them. If they do not, we take them to court. We are fighting to secure clean air for all people, regardless of who they are and where they live.

Having appropriate standards also ensures that when you are told it’s a “green” air quality day that it is indeed safe for everyone.

How to help

Earlier this year, the EPA opened a 60-day comment period on its draft regulations for PM2.5. More than 30,000 of you submitted public comments before the period ended. The government is legally bound to take note of public comments and can amend proposals based on public feedback. We are now awaiting the final rules.

But the EPA still needs to update other air pollutants that make up the National Ambient Air Quality Standards. In particular, the EPA should turn next to tightening the protections against smog, as well as sulfur oxides, nitrogen oxides, and lead.

Please sign the petition below to let the Biden administration know we we want better protections from air pollution.  

Ben serves as the Director of Content Strategy at Earthjustice. He is based in San Francisco.

Earthjustice’s Washington, D.C., office works at the federal level to prevent air and water pollution, combat climate change, and protect natural areas. We also work with communities in the Mid-Atlantic region and elsewhere to address severe local environmental health problems, including exposures to dangerous air contaminants in toxic hot spots, sewage backups and overflows, chemical disasters, and contamination of drinking water. The D.C. office has been in operation since 1978.