When it's smoky in SoCal, here's how to check how healthy the air is

Questions about air quality arise whenever plumes of smoke announce a new wildfire burning in SoCal. Is it safe to go outside? Can I send the kids to school? Should we be wearing face masks?

The Environmental Protection Agency publishes information on particulate and pollution levels around the state, called the Air Quality Index, broken down by zip code. (You can get also find that information using KPCC's Fire Tracker tool.)

Interpreting that data to determine whether the air is safe, however, and also what precautions to take, can sometimes be confusing.

To that end, we've rounded up some useful resources to help you breathe easier during a fire.

What's the Air Quality Index?

AirNow, a resource developed by the Environmental Protection Agency, determines the Air Quality Index for specific locations by taking five different pollutant measurements into account: ground-level ozone, carbon monoxide, sulfur dioxide, particle pollutants PM2.5, and particle pollutants PM10. The last two are most associated with wildfires.

The way each pollutant gets measured can get very technical, so the AQI translates the numbers into a user-friendly zero to 500 scale, says Violette Roberts, community relations and education manager with the Mojave Desert Air Quality Management District.

What do the AQI numbers mean?

Generally, if the AQI rating is between zero and 100, the air is considered to be safe for the majority of people to be active outside. When it gets higher than 100, that's when smoke advisories and air quality warnings begin going out from local air quality management districts.

Here's a chart with a breakdown of how to interpret the AQI rating in your area, and to determine what activities are safe.

A screenshot of AirNow's breakdown of how to interpret AQI ratings.

When air quality is affected by a wildfire, South Coast Air Quality Management District generally suggests a few measures for areas impacted by smoke. Those include:

Avoid vigorous outdoor or indoor exercise.
Sensitive groups, including people with heart or respiratory disease, older adults and children, should stay inside.
Keep windows and doors closed.
Run your air conditioner if you have one with a clean filter and the fresh intake closed.
Avoid using a swamp cooler or whole-house fan.
Don't use wood-burning fireplaces or other appliances inside or outside.

You may be wondering whether you should be wearing a face mask as a precautionary measure. The short answer is probably not, but if you still want to, make sure it's the right kind and that you're wearing it correctly. More on that here.

What are 'particulates'?

We live in a state where wildfires aren't uncommon, so it's not surprising we hear the term particulates on a regular basis. But what does it mean? During wildfires, the particle pollution, or fine particulate matter is measured in two different ways: PM2.5 and PM10.

Coarse dust particles: PM10

PM10 particles would include many of the small particles that you can actually see in the air. Mojave Desert AQMD's Violette Roberts described PM10 particles as about a quarter of the width of a human hair. "When you look out in the desert and you see a sand storm, most of what you see blowing is PM10 particulate matter. You can see the large particles of sand and dust," Roberts told KPCC. She said that these particles are on the larger side so the lungs typically are able to defend against them, though they may irritate your nose, eyes and throat, according to AirNow.

Fine particles: PM2.5

Imagine a quarter of the quarter of a human hair you pictured for PM10. Those fine particles would be considered PM2.5, Roberts said. "Because it is so much smaller, [PM2.5] is a lot harder to see. If you look out at smoke in the air, it has more of a gaseous look to it because it is so much finer and so much smaller," Roberts told KPCC. PM2.5 is not just created by forest fires, but also through the exhaust pipe of vehicle motors and other forms of combustion. These particles are so tiny, that they can penetrate the natural defenses of human lungs, causing respiratory problems and exacerbating existing conditions like asthma, lung and heart disease.

For more on particle pollution, read up on AirNow.gov.

Where can I find the AQI rating for my area?

Depending on where you are located, there are a few different ways you can locate your AQI rating.

South Coast Air Quality Management District: L.A. County, Orange County, Riverside County and San Bernardino County are all under the jurisdiction of SCAQMD and can check out its color-coded map to see how breathable the air is. It is updated hourly.
Mojave Desert Air Quality Air Quality Management District: MDAQMD monitors San Bernardino County's High Desert and the Blythe portion of Riverside County. The agency provides local air quality updates hourly.
AirNow: Visit the AirNow website to enter your zip code and see information about the current air quality in your area.
KPCC's Fire Tracker: Information about the air quality is listed while fires are burning. The information is pulled from the AirNow website. Generally, the rating for PM2.5 pollution is shown since particle pollution is heavily influenced by wildfire smoke, and the AQI reflects the highest-number pollutant present in the air.
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