USA Flag


U.S. States With the Worst Air Quality

May 03, 2023

Nine out of ten people in the world are breathing unhealthy air. Why is that a problem? Well, experts have linked heavy air pollution with more than 7 million deaths every year.

Are you moving states and worried about your and your family's health? If so, you should attempt to avoid the states with the worst air quality.

But what state has the worst air quality? Read on to find out.

What Is AQI?

AQI stands for air quality index. And air quality index is the shorter form of the USA Air Quality Index. The Environmental Protection Agency (EPA) uses this to report air quality.

Why does the EPA do this? Because it helps people know when they need to keep themselves safe. During higher levels of pollution, people can wear masks or other protective accessories if they must go outside.

In addition, many people choose to stay inside during times of high air pollution. As long as their home has good air filtration, those who are sensitive can stay safe.

How It Works

The AQI is a spectrum of air quality that runs from 0 to around 500. When the EPA needs to report how good or poor air quality is, they give the public a number. The higher the number, the higher the amount of air pollution in the air.

Also, the air quality gets more unhealthy as the numbers get higher. But the change from healthy to unhealthy air quality is gradual. Experts consider anything under 100 as satisfactorily healthy.

Of course, the public doesn't have to just memorize what the numbers mean. The EPA has also created and labeled six categories. Each category has 50 "units" of air quality.

AQI Categories

Each range of 50 units has a corresponding color and adjective or phrase.

The colors work similarly to a stoplight. The colors start with a green label on the good section of the AQI. As the air quality worsens, the colors move from green to yellow to red and beyond.

To be more specific, the categories work as follows:

Good: 0 to 50: Green

When experts say the air is good, air pollution poses little to no risk. There should be very few air pollution particles in the atmosphere in such a situation.

Moderate: 51 to 100: Yellow

People who are unusually sensitive to air pollution may experience some adverse health effects during moderate air quality. But most of the population shouldn't struggle when exposed to this kind of pollution.

Unhealthy For Sensitive Groups: 101 to 150: Orange

Most of the population shouldn't experience air quality issues when air pollution has reached this level. But more sensitive individuals (such as those with asthma) may struggle at this level of pollution.

Unhealthy: 151 to 200: Red

At this level, many members of the general population will start to experience minor health effects. People who are especially sensitive to air pollution will start to experience severe health issues.

Very Unhealthy: 201 to 300: Purple

At this level, everyone will experience health effects when they go outside. Everyone should stay inside when air pollution is at this level.

Hazardous: 301 or Higher: Maroon

At this point, the air quality has become an emergency. Everyone could experience severe health effects if they step outside.

Five Major Air Pollutants

Keep in mind that the danger level isn't fully determined by the amount of any pollutant in the air. Some pollutants are more dangerous than others.

The EPA usually uses the levels of certain pollutants to determine the danger levels of air quality. Here are five of the most common ones.

Nitrogen Dioxide

This is a reddish-brown gas that experts have closely linked with asthma. It tends to come from fuels such as those used in transportation.


Ozone is one of the major components of smog in cities. It often has components such as carbon monoxide, nitrous oxides, and more.

Carbon Monoxide

Too much exposure to this colorless, odorless gas can cause damage to the body's cells. People can experience breathing difficulties, dizziness, and more when exposed to high levels of this chemical.

Sulfur Dioxide

Sulfur dioxide appears from the combustion of fossil fuels used for heating, power generation, etc. People who ingest too much sulfur dioxide can have severe asthma attacks.


Children who inhale lead particles can experience anemia, slowed growth, lower IQ, and several more problems. Fetuses in pregnant women may be born prematurely or grow slowly. Lead often contaminates the dust in many different kinds of home products.

What State Has the Worst Air Quality?

The good news is that most states have good to moderate air quality on most days. There are only around 8 states that have worrying levels of air pollution. When you rank all the states together, these are the states with the worst air pollution:

  1. Louisiana
  2. Nevada
  3. Indiana
  4. Delaware
  5. Utah
  6. Ohio
  7. Oregon
  8. Tennessee
  9. Illinois
  10. Alabama

But when it comes to comparing air quality, most experts prefer to measure the air quality of cities. So you'll more easily find the current Seattle AQI and Portland AQI than the overall Washington AQI or Oregon AQI.

This is because the smog in cities can make the air quality far worse in urban areas. This tends to tip the scales and make the overall air quality less accurate. People in more rural areas may get numbers that are higher than they should be.

Get Air Filters Delivered

So now you know what state has the worst air quality. You should be able to target moving to one of the states with better air quality. Doing so should improve your and your family's health.

Of course, things don't always work out. You can't always move to the state of your dreams. But even if you can't, you can still take other measures to improve your family's health.

For example, you can change your home's air filter. Consider getting one delivered by us. Get started by selecting your filter here.

« Back to News

Newsletter Signup

Please check the captcha bellow, and click the checkmark to sign up