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Health, Science & Environment

Does Columbus really have the most polluted air among all major U.S. cities?

 A thunderstorm hovers over downtown Columbus, Ohio Thursday, Aug. 12, 2021.
Charles Rex Arbogast
A thunderstorm hovers over downtown Columbus, Ohio Thursday, Aug. 12, 2021.

A new international air quality monitoring report is making some big claims about pollutants in Columbus. It claims that out of the United States’ most major cities, Columbus has the highest concentration of the “worst” type of air pollution, known as PM 2.5.

PM 2.5, or particulate matter 2.5, is small bits of matter created during combustion, through the burning of fossil fuels in vehicles, manufacturing and energy creation. When it comes to air quality, there are typically six pollutants that are monitored. PM 2.5 accounts for about 95% of the total pollutants typically detected.

The particles can enter the bloodstream and lead to numerous health problems, and exacerbate existing health issues like asthma.

“PM 2.5 kills people on the planet more than any other pollutant. So it is the most important pollutant that we look at, because it is the most impactful health wise,” said Glory Dolphin Hammes, the CEO of IQAir’s North American division in California.

The Ohio EPA and the Mid-Ohio Regional Planning Commission are pushing back on the IQAir conclusions about Columbus, but, the company is defending its methodology. Dolphin Hammes said regulatory monitors in Columbus haven’t been painting an accurate picture of the amount of PM 2.5 in the air because there aren’t enough in operation.

“What gets measured gets done,” she said.

A map the Ohio EPA provided shows two regulatory monitors in the Columbus region, both on the outskirts. One is near Dublin at Smoky Row Road and Interstate 270, the other is in New Albany, at New Albany High School. Though, a 2021 Ohio Air Quality Report issued by the Ohio EPA shows data from a total of four locations.

IQAir admits there are other plenty of other cities more polluted with PM 2.5 than Columbus, in and out of Ohio. But, out of the country’s major cities, Dolphin Hammes said, Columbus has the most.

“Usually, Los Angeles is up there. But Columbus beat Los Angeles,” she said.

Dolphin Hammes said 10 of the 15 worst off cities in the U.S. are in California, and the state is considered the most polluted.

“We've made so many tremendous strides in air quality, we really have. But, overall, we are still the most polluted due to the population and the amount of transportation that takes place within the state,” she said.

Dolphin Hammes said IQAir’s conclusions are backed by a team of scientists and a network of sensors, even if their claim seems like a surprise.

“Columbus is considered for us the most polluted major city for the U.S., and that sounds very harsh. But yeah, it is actually, according to our measurements,” she said.

While the Ohio EPA didn’t provide anyone for an interview, they said in an emailed statement that the levels in the IQAir report aren’t representative of their data, and question the type of sensors used in the report.

“The particulate levels listed for Columbus in the report are not representative of the actual air quality in the area, which is meeting federal air quality standards,” Ohio EPA media relations manager James Lee states in the email.

The IQAir report shows the number for PM 2.5 coming in at 13.1 micrograms per cubic meter of air, just above the 12 micrograms per cubic meter the U.S. deems safe, while state reports show averages coming in between 7 and 10 micrograms per cubic meter, though spikes in the figure reached into the 20s, and up to 32 micrograms per cubic meter in 2021.

The figures are all above the 5 micrograms per cubic meter limit the World Health Organization recommends.

Lee points out IQAir sells air quality sensors.

Over at MORPC, sustainability officer Brandi Whetstone has her doubts about the report, too.

“We have some concerns about the methodology that characterizes Columbus's air pollution. For one, the report collects access data from both the regulatory grade monitors and the low-cost sensors, which can operate very differently. Combining the data from both of these can be challenging and misleading,” she said.

Lee said the placement of the sensors is also very important, and it’s unclear if IQAir followed U.S. EPA guidelines for the placement of their sensors.

Dolphin Hammes said IQAir has a network of 30 sensors to track the particulate, using sensors and monitors of different grades, including low-cost sensors known and high-grade ones like the ones used by governments. The company argues they can get a better picture of PM 2.5 because they have many more monitors in place than the Ohio EPA. She said their sensors have been tested and found to be accurate.

But Whetstone said lower-cost monitors do have problems.

“We've seen more than once where there's been foggy or misty conditions, and that did cause all of those purple air sensors to read a lot higher levels of pollution, which didn't compare to what our regulatory monitors were reading,” Whetstone said.

IQAir pushes back on that, though.

“We validate and calibrate data… So, we throw out what's called anomalies. And we calibrate based on different factors, meteorologist factors like relative humidity and also dew point, which can affect optical sensors that we have, which are low-cost sensors,” Dolphin Hammes said.

Dolphin Hammes said the Ohio EPA network may be enough to be compliant with the Clean Air Act, but it still leaves big portions of town unmonitored. She said IQAir’s data goes a step further and provides a “complete set of validated air quality data,” which allows “private citizens and community organizations to fill the data gaps in their communities.”

Andy May, an associate professor in Ohio State University’s Department of Civil, Environmental and Geodetic Engineering, said regulatory monitors do provide more accurate data than low-cost sensors, but said more data would lead to a more comprehensive view of air pollution in Columbus.

“I think a lot of other larger US cities have more EPA monitors that are actually tracking what's in the air,” May said. “Columbus is somewhat underrepresented in terms of regulatory measurements which influence the results to some extent.”

The Columbus Climate Adaptation Plan, created by Ohio State University’s Byrd Polar and Climate Research Center, the city and MORPC, appears to back the idea that the area could use more air quality monitoring. The report called for monitoring and states “traditional estimates of citywide air pollution based on a few select measurements are inaccurate.”

Following that report, MORPC and Franklin County Public Health created a new, 20-sensor network using both low-cost sensors and regulatory sensors.

The first report from that effort is expected to be released sometime in June.

“We're specifically setting those sensors around the community, so that we can see if those vulnerable populations are experiencing higher levels of pollution at the hyperlocal level,” Whetstone said.

Whetstone said people who are concerned about air quality can check their air quality forecasts so they can avoid strenuous, outdoor activity when conditions are bad.

“MORPC offers air quality forecasts in the region, for ozone and particulate matter pollution, those are the most prevalent that can impact public health when pollution levels are expected to reach unhealthy for sensitive groups,” she said. “That includes children, older adults, people with asthma and COPD, we issue an alert to the public, to make them aware that they need to pay attention and maybe take some steps to reduce exposure to air pollution.”

IQAir and the EPA also have monitoring services.

Renee Fox is a reporter for 89.7 NPR News.