How unhealthy is the air outside right now? You don’t need your own sensors to find out. Here’s how to find out how bad smoke and pollution is in your area – or anywhere else.
Understanding the Air Quality Index (AQI) Score
All of these services show an Air Quality Index number. The higher the number, the more pollution in the air at this time.
Note that different countries use different Air Quality Index systems. If you are not in the US you should look at your country’s Air Quality Index standards.
In the US, this is what the numbers mean:
|Color||Air Quality Index (AQI)||Level of Health Concern|
|Green||0 to 50||Good|
|Yellow||51 to 100||Moderate|
|Orange||101 to 150||Unhealthy for Sensitive Groups|
|Red||151 to 200||Unhealthy|
|Purple||201 to 300||Very Unhealthy|
|Maroon||301 to 500||Hazardous|
Timely Crowd Source Report: PurpleAir
While there are a number of ways to get official numbers from standard government sensors – and we’ll explain them in a bit – there is one way to get more timely results.
PurpleAir shows a more local air quality number. They are much more up-to-date but are sourced from the multitude of sensors installed by individuals. Individual sensors in an area may not be accurately placed. However, if you look at an area with multiple sensors, the average will show you a fairly complete picture.
Just go to the PurpleAir map and look for your local area (or any other area you’d like to inform.)
If a particular sensor is too high or low compared to the surrounding sensors, you should ignore it. That said, the sensors in your area should show a fairly accurate average reading at this point. They may even suggest differences from neighborhood to neighborhood in your city.
The PurpleAir sensor shows US AQI numbers even when they are in another country, so you can look around the world and compare readings across multiple countries, if you wish.
Slower Official Numbers: AirNow and Smartphone App
You can also check the official numbers reported by your government. In the US, these numbers are provided by the EPA and its partners. They are updated hourly and come from fewer sensors which are more accurate.
That’s easy, but they won’t show you the most precise air quality details if it’s changing rapidly or how air quality differs from neighborhood to neighborhood in your city.
To find this number in the US, Canada and Mexico, you can use the AirNow website. Plug in the location and you will see the air quality in your area. (For other countries, you will need to search a website with data for your country.)
AirNow also offers maps showing air quality across North America.
For convenience, you can quickly find these numbers through the smartphone application. On your iPhone, the Maps and Weather app displays air quality information. You can view your local air quality information or view other areas on the map and their local air quality. (This is not available in all countries.)
On Android, you can ask the Google Assistant about the air quality in your area or other areas. (Again, the Google Assistant doesn’t support this in every country.) You can also install third-party apps that display this information.
Both the Apple and Google apps display the same official information you’ll find on AirNow and on government websites. For multi-sourced information, go to PurpleAir.
If you want to learn more, Wired explains well the differences between the numbers on PurpleAir and AirNow and how they are measured.
Government-generated figures are official canonical historical data for an area – however, with conditions changing rapidly and varying from location to location even within a particular city, PurpleAir figures may be more useful today.