Four questions to ask about air quality alerts

Illustration by Ella Abbott.

Every once in a while I get an alert to my phone from one news source or another about an air quality alert. Being from Cleveland, I typically get the notifications from and they usually increase during the summer months.

Even no longer living in Cleveland, those alerts could be startling when I didn’t know what they meant. Often encouraging readers to avoid outdoor activities and stay inside, if possible. So, what did that mean for my family and friends going about their daily activities?

I decided to find out what exactly an air quality alert means and when we should really worry about them.

What is an air quality alert?

Air quality alerts use the Air Quality Index, which was developed by the Environmental Protection Agency (EPA), to monitor air quality all over the country. When the air quality reaches a certain level on the index, which monitors five specific pollutants as regulated by the Clean Air Act, they send out an alert for that area.

Air quality alerts increase in the summer due to pollutants that are worse in the summer — because of things like more sunlight, longer days, more ultraviolet radiation.

What are the pollutants being monitored?

There are five major pollutants that are monitored by the Air Quality Index, according to the EPA. These pollutants are regulated by the Clean Air Act, which was established in 1970 due to the decline in air quality around the country.

1. Ground-level ozone

The word “ozone” is probably familiar because it’s talked about a lot in relation to climate change. Ozone is a toxic gas that differs from oxygen because it has three oxygen atoms rather than one. When ozone exists up in the stratosphere, it creates a protection from harmful ultraviolet rays. But when it reaches the ground, it becomes a major component of smog. According to Columbia University’s State of the Planet blog, ozone “can cause coughing, chest tightness or pain, decrease lung function and worsen asthma and other chronic lung diseases.”

The blog also says that ozone causes about 400 premature deaths, more than 800 hospital visits and 4,000 emergency room visits in New York City each year.

2. Particle pollution

Particle pollution, or particulate matter, is defined by the EPA as “a mixture of solid particles and liquid droplets found in the air.” This includes large particles like dust, soot, dirt or smoke, but it also includes particles that can’t be seen with the naked eye.

Particles this small can easily be inhaled and cause serious health problems. The EPA says the smallest particles are the most dangerous because they can get deep into your lungs or even bloodstream.

3. Carbon monoxide

Most people probably grew up with some kind of carbon monoxide (CO) detector in their home. It’s a colorless, odorless gas that can easily go undetected and cause carbon monoxide poisoning The Centers for Disease Control and Protection says “the most common symptoms of CO poisoning are headaches, dizziness, weakness, upset stomach, vomiting, chest pain and confusion.”

Carbon monoxide forms when carbon doesn’t burn correctly, so it can be created anytime you use something that burns fuel, such as cars, trucks, stoves, grills or fireplaces. State of the Planet says high levels of carbon monoxide occur more often in cold weather because “cold temperatures make combustion less complete and trap the gas closer to the ground.”

4. Sulfur dioxide

You may remember sulfur dioxide from last week’s post about acid rain. This is the stuff that helped contribute to acid rain, which led to regulations on coal-fired power plants like scrubbers and coal washing. As I explained last week, sulfur dioxide is an emission created when we burn fossil fuels. It enters the atmosphere and creates more toxicity.

5. Nitrogen dioxide

Nitrogen dioxide is another type of gas that enters the atmosphere as a result of burning fuel. It forms from emissions from cars, trucks, buses, power plants and off-road equipment, according to the EPA. Breathing nitrogen dioxide can irritate a person’s airways and exposures over short periods can aggravate respiratory diseases. The EPA says this can lead to hospital admissions and emergency room visits. Longer exposures can contribute to the developments of asthma.

Who monitors the air quality and sends out alerts?

Air quality monitoring is a joint effort between the EPA and the National Oceanic and Atmospheric Administration (NOAA). They issue daily air quality forecast guidance, according to the National Weather Service. You can use the website, which is run by the EPA and NOAA, to check air quality all over the country.

What do the different colored alerts mean?

When you go to AirNow and select a city, you’ll notice the website breaks things down by a color-coded system. This brings us back to the Air Quality Index (AQI) I mentioned before. The index runs from 0 to 500 to measure the quality of the air. As you might guess, as the pollution in the air increases, so does the AQI value.

AirNow provides a breakdown of each color that explains what the corresponding index value is and what each color means.

air quality
Screenshot of AirNow’s AQI table.

Once we understand what the index means and how to use it, we can better protect ourselves from health hazards and know not to panic when that alert pops up on our phone.

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