This summer’s West Coast wildfires brought images of flames licking at swaths of land and skies choked by thick smoke, which traveled far and wide to leave people states away experiencing the effects of particulate in the air. While one consequence of the smoky air proved positive for some — gorgeous, intensely colorful sunsets — the effects by and large have been negative, with people resorting to staying indoors to avoid breathing the polluted air.
The fires have brought renewed attention to a sometimes overlooked factor that affects every single human’s life: air quality.
More cities are working to improve air quality through measures to reduce industrial pollution as well as vehicle and commercial building carbon emissions. And with the move toward greater connectivity, data use and smart city device installation comes the growth of air quality sensor use.
How they work
Cities including Chicago, Seattle and Portland, OR have launched air quality sensor pilot programs. Chicago’s project began this year as part of its Array of Things (AoT) connected urban sensor program. The city currently has 100 devices installed and an additional 100 will be operational by year’s end, on the way to the ultimate goal of 500.
The existing units measure “seven different gases including ozone, carbon dioxide and nitrogen by using experimental electrochemical gas sensors. They also have particulate matter sensors,” Charlie Catlett, senior computer scientist at Argonne National Laboratory and the University of Chicago, told Smart Cities Dive.
The particulate matter sensors detect pollutants of certain sizes, with measurement registered in microns. The AoT sensors are referred to as PM1, PM2.5 or PM10, meaning they detect particulate matter of 1, 2.5 and 10 microns or less, respectively.
“Things like pollen are in the 20-40 micron range. These [measurements] are smaller than pollen,” Catlett said. “PM1 and smaller are the ones that are super dangerous. But PM2.5 is one of the key measurements to get a sense for air quality, and it’s also dangerous stuff.”
Most of the AoT devices are installed on street lamps at a height of about 20 feet to prevent tampering, but the AoT team also is testing some on bus shelters at a height of about 9 feet.
Researchers want to get an idea of not just what is in the air, but specifically where the pollutants occur in the highest concentrations.
“It's not enough to say ‘everyone on the South Side of Chicago is exposed to this much PM2.5.’ What we’d rather say is ‘everyone in this neighborhood, or on this block is exposed.’ The variation across a city is huge with respect to air quality,” Catlett said.
The air pollution variation throughout cities and the desire for greater specificity also prompted environmental intelligence company Aclima to pursue more advanced air quality sensors.
“Measurement for air quality is extremely limited. … The current look at air quality is really regional and it’s averaged,” Kim Hunter, vice president of communications and engagement for Aclima, told Smart Cities Dive. “Pollution is hyper local. Pollution at the street level can shift five to eight times along a city block. … But traditionally we have lacked the measurement tools to look at it at the city level and the street level.”
The company offers an air quality mapping platform that aggregates data from its stationary and mobile sensors. With the mobile system, vehicles are outfitted with sensors and hardware inside the car about the size of two shoe boxes. Drivers navigate the vehicles to different parts of a city and through cloud computing, the air quality data is processed and mapped nearly in real-time. The mobile systems also prevent self-contamination from the device carrier vehicle.
“By using vehicles that are regularly crisscrossing the city, we've refined the technology to be able to geo-locate, time stamp and analyze the air as we're driving. That’s giving a spacial resolution that's 10,000 times more granular than the current regional air quality measurements,” Hunter said.
A variety of purposes
While a tech crash course can explain how air quality sensors work, answers are still emerging to the most important question: How can this technology benefit cities and citizens?
The obvious answer is by improving the environment, and thus citizens’ health. “The potential for this technology is to support health interventionists,” raise public awareness and “paint a better picture for public policy makers,” Hunter said.
Easy, real-time access to hyper local pollution data can inform city leaders' policy decisions about infrastructure, traffic and pollution mitigation programs in high risk areas, in addition to implementing health programs. Health departments could send out social media messages or push alerts on mobile devices warning citizens with respiratory issues of poor air quality in certain parts of a city.
“Pollution is hyper local. Pollution at the street level can shift five to eight times along a city block. … But traditionally we have lacked the measurement tools to look at it at the city level and the street level.”
Vice president of communications and engagement, Aclima
Wildfires produce pollution that cities can more closely monitor with air quality sensors, especially as concerns grow about this year’s extreme example becoming the new normal. Aclima deployed its mobile technology during last year’s fires in wine country north of San Francisco.
“These sort of mobile networks can be really valuable as we’re starting to experience more pollution events from wildfires,” Hunter said. “They can better pinpoint how the smoke is moving and where it’s going” so leaders can warn residents even before the plume reaches their area.
One of the projects Aclima undertook in Los Angeles examined pollution near schools, and the data prompted the acquisition and installation of improved filtration in different schools. “There are specific interventions that help cities make better fiscal decisions and solutions to intervene,” Hunter said.
The sensor data gathered from Chicago’s AoT project is “open and free to anyone who wants it, whether that’s a city or university or individual,” Catlett said. “We’re finding it's extremely useful to the smart city vendors who don't really have the kind of scientific expertise we have at our disposal," he added. "They do well on smart lighting and controls and things, but what we're able to provide the industry is insight into how you ought to think about packaging and deploying sensors.”
The AoT sensors don’t simply track air quality, either; they measure a total of 20 different conditions. In addition to the seven gases and particulate matter, the sensors track temperature, humidity, barometric pressure, vibrations and noise as well as different kinds of light.
“We can get solar load information because we measure ambient light — infrared and ultraviolet,” Catlett said. The vibration and noise detection components can determine the “noise people are exposed to, which is particularly important overnight when they’re trying to sleep,” he said.
“This technology is a tool to help us acclimate to a changing environment and changing climate. The world is galvanizing behind action and we're working toward more tools to take those actions.”
Vice president of communications and engagement, Aclima
The more types of data the systems can aggregate and analyze, the more meaningful the information becomes and the more intervention programs cities can formulate.
“If you’re just measuring one thing like air quality but you don’t have any information about other things like traffic flow or temperature or humidity, you’re not going to be as well equipped to figure out what is causing air quality to change,” Catlett said. And without fully understanding changes, leaders can’t devise effective solutions.
To further assist technology developers, the AoT team will test and provide data from specific types of sensors installed around Chicago by special request. That helps developers decide which features to include in their products, and cities can learn which features are important to them before procuring devices.
Part of Aclima’s growth strategy is to expand its air quality sensor deployment to fleets of vehicles, such as ride-sharing or city bus fleets.
“This technology is a tool to help us acclimate to a changing environment and changing climate,” Hunter said. “The world is galvanizing behind action and we're working toward more tools to take those actions.”