How To Check Air Quality in US - CycleBlaze

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How To Check Air Quality in US

Kathleen Jones

Because of our new reality of massive wildfires in the western US and elsewhere in the world, cycletourers may want to know of a couple of online resources to check the air quality index, or AQI. Two of them are the EPA’s Air Now site, and Purple Air, a commercial site, which is useable worldwide.


The Environmental Protection Agency (EPA) site is It has many different layers that you can toggle. The advantage of this map is the smoke plume extent. What the smoke plume layer does not tell you is if the smoke is upper-level or ground level. The air sensors however can help with that, as well as local weather reports.

NOTE: The page takes a little while to load initially. I usually dismiss the dialog that pops up asking for location, then reload the page. The default layers then load. Then I zoom in to the area I’m interested in and play with toggling the layers.

This view shows all types of sensors and the smoke plume extent. Note the layers dialog on the right side. Click the layers icon (above in the bar) to open. Select the layers you want to show with the check boxes.
The chosen layers are smoke plume and incidents, both large incidents and satellite-detected.


In the EPA site, you’ll notice one layer of sensors is called “low-cost.” These are from a network of sensors sold to the public by manufacturer Purple Air. Their own map of these sensors is helpful in its own right ( The advantage of this map is that the sensors are sold worldwide, so you can check AQI in Australia, for example. The disadvantage is that these tend to be in the wealthier areas where there is reliable electricity, internet and population.

There is a conversion factor used for different air pollutants, and this year wood smoke is one of them. I’m not sure if the EPA incorporates this new conversion or not when they use these sensors on the Air Now map.

Map of Purple Air sensors showing air quality. This shows outdoor sensors only.
Be sure to change the conversion factor to Woodsmoke in the box in the lower left of the screen. Also note the scale; if you hover your mouse over the gradient it shows an explanation of health effects at the various levels. It’s also helpful to deselect indoor sensors here.
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1 year ago
marilyn swettTo Kathleen Jones

Thanks for posting this info Kathleen. I had heard of the Purple site but never used it. Don has been using some air quality site that shows air monitoring stations and the air quality index in each. 

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1 year ago
Lucy MartinTo Kathleen Jones

Good post.  You can download the Air Now app on your smartphone too.  There are a bunch of other similar apps but I don’t know about their quality.  Air Now I check every day.

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1 year ago