It’s Easy to Check the Air Quality. Meet the People Collecting That Data for You

When smoke from eastern Canadian wildfires smothered much of Canada and the American East Coast this summer, it resurfaced a distant memory for Gus Sentementes. The last time smoke descended on his home in Baltimore, Maryland, was in 2002, when fires in Quebec spread smoke more than 700 miles southward.

But this summer was different. The smoke lingered longer and spread farther. It also created quite a stir in areas that aren’t used to being that close to the effects of a cataclysmic wildfire. The world is warming, extreme heat is spawning hellish blazes, and even those not in the immediate vicinity are feeling their effects far downwind. Sentementes felt like this wasn’t just a fluke—something that affected his life every 20 years or so. This felt like something that would likely happen again, and soon.

Like anyone who breathes (i.e., everybody), air quality always felt somewhat important to Sentementes. He has three kids, one of whom has asthma. Sentementes himself uses a sleep apnea machine at night. When the sky turned orange and taking a breath felt like sucking in a campfire, Sentementes decided it was time to learn more about how his air quality was changing. He bought a PurpleAir sensor that lets him monitor the air quality outside his house in real time and share the data on the internet, where it gets pooled with other sensor readings from down the street, across town, and around the world.

“It’s been an eye-opening experience, the last several months, just coming to understand the basic, most fundamental importance of clean air,” Sentementes says. "We just really don’t appreciate it until you’re forced to breathe in a lot of terrible air.”

Wildfire smoke has long been a staple of the summer months along the West Coast of the US. Earlier this summer, when the wildfires in eastern Canada burned thousands of acres and covered the east coast in clouds of acrid haze, people who had never known life in wildfire country found themselves choking on wildfire smoke. As wildfires worsen and spread, people in communities that aren’t historically thought of as wildfire prone are starting to track the smoke in their air.

“With all that's going on with climate change and all the extremes that everybody's experiencing, sadly, I think this is going to become the new normal,” says James Knox, who lives near Ottawa, Ontario, Canada. “We're going to have to start living with this.”

Knox recently bought two PurpleAir sensors after this summer's wildfires. He placed one in his yard at his home and the other at a family cottage a few miles away. Knox has consulted for public health agencies about Covid-19 and other infectious diseases. Being forced indoors due to the Canadian wildfires evoked the lockdown days of the Covid pandemic, albeit with its own twists. Back then, the guidance for social distancing allowed for outdoor excursions, like going for a walk. For someone like Knox, it was a way to stave off cabin fever and get some fresh air. But when the smoke came, he felt pinned inside without respite.

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“We've been kind of conditioned to going out in fresh air, but that's dangerous now,” Knox says. "It’s a weird feeling.”

It’s relatively easy to check your community’s air quality. At least, if you live in the US, and also in an urban area that’s mandated to report such data to the Environmental Protection Agency. The Air Quality Index, or AQI, is the measure of potentially harmful particulate matter in the air around us. The readings focus on particles smaller than 10 micrometers (PM10) that are easily inhaled, like dust or pollen. The really small particles, anything below 2.5 micrometers (PM2.5) have greater potential to travel farther and more easily seep into your lungs. Those are the particles of wildfire smoke that can spread for hundreds of miles. Official sources like the World Health Organization and the US-focused AirNow track air quality, usually more rigorously in populated areas, and rank the ratings on a scale from Good to Hazardous.

AQI readings have traditionally been taken by big, pricey measuring instruments owned and operated by state or local governments. But over roughly the past half decade, small, low-cost devices have democratized air quality monitoring. Companies like Purple Air and IQ Air have built up reliable air quality tracking networks made up by citizen-owned monitors; PurpleAir says it has more than 25,000 units in its network worldwide. These monitors are cheap devices that hook up to your Wi-Fi network and are easy to install. The sensors take regular air quality readings and then upload the data to the broader networks, offering a crowdsourced snapshot of air quality information that spans the globe. The devices aren’t perfect—there’s a greater chance of human error when the monitors aren’t placed by someone who’s trained to collect air quality readings—but the sheer scale of the network means inaccurate outliers have a higher chance of being drowned out by the sea of other nearby devices.

A platform like PurpleAir also makes the data immediately accessible by visualizing the air quality readings on a map, using a color-coded scale from blue and green (OK) to red and purple (very bad). Even if you don’t fully grasp particulate matter ratings, seeing a big red blob on a map over your house is a pretty quick way to tell something is off.

“It’s a form of engaged learning,” says William Mills, an exposure assessment researcher at Northern Illinois University. “You can touch it, you can feel it, you can see it. It’s community sharing that’s just easy for people to opt in to. You can gain as much or as little information as you want. Can we use that to look at other forms of environmental quality? Can we use it to help change behaviors?”

Making the data more accessible can make people more interested in paying attention to it, especially when disaster strikes. Elizabeth Spike is an alternative school teacher and the education program manager at Clean Air Partners, an advocacy group for air quality awareness based in Washington, DC.

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“Between the wildfires and Covid, I think more and more people want to know what they are breathing,” Spike says. “It's terrible that it takes these tragedies, these crises to make us realize we've been sleeping at the wheel. We have no choice but to breathe, and yet we really haven't made a big deal about what we are breathing.”

Ammar Rai is a software engineer in Maryland. He’s had asthma since childhood, which was only exacerbated by a bout of Covid two years ago. When the wildfire smoke descended this summer, he wore a painters mask with built-in ventilators when going outside. Rai says he often feels like people with conditions like his are treated as a burden, until something like the summer’s wildfires brings widespread attention to air quality.

“People like me are like the canaries in the coal mines,” Rai says. “The stuff that we’re oftentimes reacting to is bad for you anyways. Somebody who may be perfectly fine and not show any apparent symptoms, they're getting exposed to this stuff too. Then many years down the line, you find out they’re impacted by it, or it's in their bloodstream, or they have some kind of lung disease.”

Indoors, his home is a veritable air quality fortress. He has four air purifiers in the house. He has phones mounted to a wall in each room of his house that let him see air conditions at a glance. They’re always on, and their interfaces evoke the multicolored blinking lights of the inside of a Star Wars spaceship.

He’s made his software dashboard for mobile devices available on Github, along with self-made data visualizers others can use to make sense of their Purple Air readings. Rai has a PurpleAir monitor of his own that he says nearly 500 people on the platform have favored as a resource in the area.

“It feels good to be able to provide this data to the community in some way and raise awareness,” Rai says. “My standards are probably different than other people's, but if it helps someone have a good day outside, hey, that's great. Wonderful.”

James Knox, in Canada, also hopes sharing his data will help researchers and forecasters looking to predict unhealthy air events in the future.

“I feel fortunate I'm in a position to be able to do this,” Knox says. “I can provide that information, and people can make use of it to inform their lives. It gives them better situational awareness. People are nervous. People are worried. This helps.”

Gus Sentementes says there’s a sort of camaraderie to it too. It's a spirit, he says, that feels like it has been squeezed out of much of the wider internet by a handful of big social media companies intent on monetizing their platforms at all costs and erecting walled gardens around their services.

“One of the gee-whiz wonders of the internet of the early days was this feeling of being connected to other people,” Sentementes says. “It’s community driven, community sourcing. There’s this sense of a collective project you want to contribute to. You’re not just taking from it, you’re giving something back.”

Update August 28, 2023: Corrected the distinction between PM10 and PM2.5 particles. PM2.5 can include wildfire smoke and the effects of combustion of gasoline or diesel, not just gas fumes.