Smaller, cheaper monitors can turn non-experts into air pollution sleuths, if the devices work as promised and the sampling approach is smart.
By Catherine Clabby
In uptown Charlotte this summer, people concerned about air quality in their city fanned out on foot, bikes and light rail one hot evening to measure air pollution.
Not government regulators or atmospheric chemists, but residents young and old who answered a call from the advocacy group Clean Air Carolina to try out a new breed of sensors to observe pollution in the city air.
J.D. Doliner brought her 10-year-old daughter, a middle school student. Doliner frequently reminds her daughter that tiny, invisible particles of pollution float around them even when they can’t see them.
“If we are walking uptown and going past a taxi stand, I’ll tell her that they are higher. When we’re under a tree, I say they are lower. She’d look at me like I’m from Mars,” Doliner said. “But when she could see it, you should have seen the synapses fire.”
That is just the reaction Terry Lansdell, program director at the nonprofit was aiming for. “Air quality is a topic that is tough to get people interested in because it’s invisible,” he said ”Using the monitors is a way to help them have an ‘Aha!’ moment. It can help you become aware of pollution.”
New tools, new challenges
Clean Air Carolina is one of many groups nationally putting a new breed of monitors into the public’s hands to facilitate citizen-science research projects and to better educate people about what’s in their air. These monitors are smaller, simpler and cheaper than the devices that government officials or scientists have used for decades to detect air pollution.
If properly deployed, the devices hold promise to reveal important information about air quality that more complex but stationary sensors could miss, say state and federal air quality experts. If misused or of poor quality, however, they could produce measurements that are not useful in research and could unnecessarily alarm people.
For that reason, the U.S. Environmental Protection Agency is reaching out to non-scientists with workshops and publications to brief them on the potential and perils of these new devices.
Interest in do-it-yourself air testing is so high that an EPA web-based “toolbox” offering guidance on using the low-cost monitors is one of the most frequently visited webpages created by the agency’s Office of Research and Development, said Ron Williams, a research chemist who is among the federal staff evaluating new sensors and reaching out to users.
The new sensors, produced in multiple countries and marketed globally, cost roughly $100 to $300. The handheld sensors may measure just one pollutant, said Williams, who works in the EPA’s National Exposure Research Laboratory in Research Triangle Park. Traditional, larger units can cost up to $10,000, are not easily moved, and can detect multiple toxins or chemicals that produce toxins in the atmosphere.
People need to understand what they are buying and whether a sensor is right for their projects. To help, EPA is also evaluating the new devices in field studies and posting findings online. No industry program is yet assessing the performance of these products, even though they are being produced in the United States, Europe and Asia.
“There is an explosion of groups trying to develop and market these types of monitors,” Williams said.
Making the most of devices
By any assessment, air pollution is a complex area, Williams said, and people measuring pollutants in any context need to develop a degree of expertise.
The EPA has maximum permissible levels for multiple contaminants known to make people sick, including ozone, which is produced near the ground when hydrocarbons and nitrogen oxide gases interact. The agency also has established levels for minuscule clumps of soot called particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide and lead.
But repeat measurements are needed to recognize which conditions are excessive. Acceptable levels for some particulates, for instance, are based on hourly monitoring measurements averaged over 24 hours. Variation over time must be considered. Concentrations of a toxin may vary by the time of day, the day of the week, and the season.
That produces more data than simply filling a vial with water or soil and shipping it off to a laboratory to screen for fecal chloroform bacteria or traces of pesticides.
“If you are trying to take measurements you have to think like a scientist,” Williams said. “People will ask you hard questions. What was the device used to collect the information? How is it calibrated? Do you know it’s accurate?”
Clean Air Carolina has taken pains to dig into the details, Lansdell said.
With a $36,000 grant from the Z. Smith Reynolds Foundation and its own fundraising, the organization purchased several AirBeam monitors. The units use scattered LED light to detect and measure the density of fine particles, 2.5 micrometers in diameter and smaller.
Such particles can lodge deeply into a person’s lung and exposure to them has been linked to premature death in people with heart or lung disease. They can also aggravate asthma and worsen airway irritation and breathing difficulties.
An open-source app called AirCasting, receives the data on a smartphone via a Bluetooth connection and uses it to create a web-friendly map visible to anyone if posted in a public place.
Seizing the opportunity
Clean Air Carolina staff, including college student interns who helped organize the first outing this summer, are collaborating with Brian Magi, a climate researcher at the University of North Carolina, Charlotte.
Magi has helped Clean Air Carolina calibrate their monitors by comparing their readings with a more sensitive sensor he has. (The mini device so far seems to detect less.)
“That’s not a bad thing,” he said, as long as you know it.
Air quality has improved across North Carolina in recent years, including in Charlotte, thanks to state and federal regulations reducing emissions from vehicles and industry, especially coal-fired power plants. But pollution has not disappeared. After seeing reduced levels of ozone, Charlotte has experienced unhealthy ozone this summer, in part because the federal government lowered its minimum levels of safe ozone.
And as the city’s and state’s population continues to grow, these exceedances may become more common.
“We want people to recognize that our air quality is largely good,” Magi said. “And that is something we should protect. It’s hard to emphasize protecting what people can’t see. That’s why it’s good to make this effort.”
Clean Air Carolina is bringing its monitors into Mecklenburg County schools and into three northwest corridor neighborhoods to teach students and residents about the constituents of air pollution and how to collect reliable measurements of particulates in the air. The organization will encourage participants to advocate for reducing the pollution they encounter.
For Doliner, the mother who brought her daughter to Clean Air’s demonstration in Charlotte, the education alone offered by monitors is valuable.
“It’s doing something to improve awareness,” she said.
Williams at EPA agrees that getting individuals more tuned into the risks from pollution is a potential benefit from getting the new air quality monitors in more hands, if the devices produce meaningful measurements.
“There are a wide range of applications,” Williams said. “If you ask people what they are exposed to on a daily basis, they can’t tell you. But we’re all exposed.”
Correction: This story originally misidentified the location of the Charlotte neighborhoods to be included in the Clean Air Carolina project.