I live in Arizona. Far enough away from the apocalyptic destruction on the West Coast that my skies haven’t turned orange like a scene out of Blade Runner just yet. The key word there being yet. As bad as things are in California and Oregon it’s only a matter of time before the smoke drifts through the Sonoran desert down to Scottsdale before heading out to spread misery across the rest of the nation. And Arizona itself is no stranger to forest fires. It’s just going to get worse from here on out. Much worse. Year after year as Climate Change worsens.
Things are already so dire that I’ve begun to contemplate how I’m going to navigate through the hellscape that I now find myself in. All things considered, tonight was actually a nice night in the Valley with temperatures finally dipping below 115 degrees. In fact, it’s only 76 right now! Almost as extreme of a drop as Colorado saw this week when it was 90 degrees one day and snowing the next. Certainly it was a nice night for a stroll. A rare opportunity to sit outside and read a book. But was it even safe to go outside? If COVID doesn’t get me the toxic air quality might.
The problem is I have no idea how to figure out what my actual risk level is. How does one go about determining how safe the air quality in their general vicinity is? Enter PurpleAir. A website that aggregates data from their network of sensors to let you know exactly how safe or toxic the air in your area is.
As Wired puts it:
“Drawing crowdsourced data from air quality sensors it sells to the public—ranging between $200 and $300—PurpleAir builds maps that show in real time just how bad a neighborhood…is suffering from particulate matter (PM) 2.5 pollution, the particles that make up wildfire smoke. (PM 2.5 means 2.5 micrometers in diameter, a size the Environmental Protection Agency deems ‘fine inhalable particles.’) This summer I’ve been checking it obsessively, watching the air quality index, or AQI, swing wildly from the green-is-good indicator that indicates a PM 2.5 score in the low teens up past the alarming purple of a 200 score. I do this knowing that PurpleAir’s sensors are necessarily imperfect, and because they are deployed at home by customers, not by an environmental agency, they are not meant to serve as official measurements of air quality. Still, they’re an important source of data even for government bodies, like the Bay Area Air Quality Management District, whose own sensors feed the EPA’s AirNow.gov tool, which also uses a green-to-purple color scale.
Apparently I’m not alone in my obsession. As AQI scores have soared in the Bay Area over the past month and a half, so has PurpleAir’s business. ‘We’ve seen 1,000 or more percent increase in traffic on the site,’ says Adrian Dybwad, the company’s founder and CEO. ‘We have a whole heap of emails—people calling. We have a lot of activity going on right now. We’ve had to increase our staff to make more sensors, because we make them ourselves.’ Nine thousand of these sensors are now distributed all around the world, which you can see on this map. If you zoom on the West Coast, you’ll see atrocious AQI numbers—some over 700—as wildfires rage across Washington, Oregon, Colorado, and California. (Yes, 700 is higher than PurpleAir’s own map legend, which stops at 500.)
Those sensors work quite differently from the ones the Bay Area Air Quality Management District is using to monitor AQI. Inside a PurpleAir sensor shines a laser beam, which illuminates particulate matter floating in the air, a technique known as light scattering. Think of it like shining a flashlight through the desert—you’ll see all kinds of dust particles moving about. ‘The intensity of the reflection will give you an idea of the size of the particle, and then the number of reflections gives you an idea of the number of particles,’ says Dybwad. A PurpleAir sensor converts these counts into an estimated mass of the particulate matter, which is then converted into the AQI you see on its maps.”
In other words there’s now a way to find out, quickly and easily, just how safe your area is. But I still think we’re going to go need one step farther at this rate. Perhaps even inventing geigercounter like devices that we carry around and scan right in front of us to let us know if we can take our masks off and breathe freely. Yes, sadly it’s heading in that direction. Orange air. PurpleAir. It’s all here to stay.
Leave a comment