By: Angelia Coenen and Keita Kawahara
With pollutants being pumped into our atmosphere every day, the need for sensors to monitor changes in air quality is becoming increasingly apparent. The lack of consistent monitoring across the US makes it difficult to keep track of our air quality, and many areas lack the proper awareness to engage in better monitoring. To raise awareness for this problem, it is important that we are aware of its magnitude, so let's begin by explaining what air quality is, what air sensors are, and what they do.
What exactly is air quality?
The Environmental Protection Agency (EPA) monitors 6 main air pollutants. These include particulate matter (PM), ozone, nitrogen oxides, sulfur oxides, carbon monoxide, and lead. The air quality of an area is determined by how much of these pollutants are being sensed at a certain time. PurpleAir is a more accessible way for people to take action within their communities and start tracking air quality.
Purple Air sensors across the United States
What do these dots represent?
Every dot is a PurpleAir sensor in the US and its color is indicative of where it falls on the Air Quality Index. This is calculated by measuring the six primary pollutants on a scale of 0-500.
0-50 is considered good and is represented by the green dots. 51-100 is considered moderate and represented by the yellow dots. After 100 is where the dots start to become orange, red, purple, and maroon which represent air quality indexes that are dangerous for humans.
As shown above, these dots are not evenly dispersed. While there appears to be a huge amount of sensors in areas like California, there are visible gaps in the map in other places. Even focusing on California which seems to be the most populated with PurpleAir sensors, a zoom in reveals that there are still significant data gaps.
Starting at the top of California:
Up near Sacramento:
Moving lower, around Fresno:
Down into bakersfield and LA:
And finally, down into San Diego:
Throughout these images, there is a concentration of sensors near large cities, but with further zoom-ins. the lack of proper monitoring in large areas becomes very easy to spot.
Even in what seems the be the area with the most sensors in San Diego, we can still see many dead zones:
While seeing so many dots that are not green may be discouraging, having access to accurate data is the first step to improving.
Works Cited
AirNow. “Air Quality Index (AQI) Basics.” AirNow, 2021, www.airnow.gov/aqi/aqi-basics/.
Loiacono, Milan. “What Is Air Quality? - NASA.” NASA, 18 Oct. 2024, www.nasa.gov/general/what-is-air-quality/.
