Why poor air quality isn’t just a summer problem in Detroit

While government monitors shown on the AirNow site may be more accurate than third-party monitoring networks like PurpleAir, they may not provide as much detail because they take less frequent readings and are less numerous.

That means the official air monitors may miss pollution that third party sensors pick up.

The bad air’s culprit, according to meteorologists, was an ‘atmospheric inversion’ in Michigan that happened earlier this week, leading to stagnant, polluted air. This is a common winter phenomenon where warmer air, which normally sits close to the ground, rises and creates a cap on the colder air beneath. This trapped air can keep particulate matter near the surface, posing a risk for those most vulnerable to PM 2.5 pollution, like older adults with heart and lung conditions and children.

While ozone pollution tends to occur only in the warmer months and can lead to air quality alerts called “ozone action days,” PM 2.5 pollution can happen any time of year. Alec Kownacki, a meteorologist with EGLE’s air quality division, said atmospheric inversions tend to make PM 2.5 worse in winter than in summer.

Up until this past summer, EGLE didn’t issue alerts for PM 2.5. However, that changed when wildfire smoke brought extremely high levels of particulate matter to the area, leading EGLE to begin issuing air quality alerts for PM 2.5 for the first time.

So far, the agency has not issued a PM2.5 advisory in the winter. However, Stephanie Hengesbach, a meteorologist with EGLE, said in a statement to Planet Detroit that the agency would issue warnings at any time of year, “if we feel the daily average PM2.5 value in a general location (area) will reach the Unhealthy for Sensitive Groups (USG – Orange AQI) range or higher.”

“People with asthma and respiratory illnesses, they’ll be the first to notice it because it’s hard for them to breathe,” Kownacki said about high particulate matter levels. He added that unlike ozone, which primarily affects those with respiratory illnesses, the effects of PM 2.5 are felt by many others.

Hengesbach, said that the highest PM 2.5 levels often occur after a snow accumulation when the temperature increases, and wind decreases.

“If these conditions persist, they will lead to a period of stagnation with increased surface moisture,” she said. “This set-up can lead to longer-lasting inversions that may persist during the day, allowing for fine particulate pollution to pool and increase at this surface.”

Snow itself can trap particulate matter, releasing it when the weather warms up. Jim Haywood, senior meteorologist for EGLE, added that the burning of fuels for home heating over the winter and idling vehicles for warmth can also contribute to PM 2.5 levels.

When wind and precipitation moved into Michigan on Monday and Tuesday it allowed pollutants to mix upward into the atmosphere and cleared the air, a trend that EGLE meteorologists expect to continue as further storms hit the state going into the weekend.

In the future, it’s possible that the warming winters associated with climate change could create more issues with winter particulate matter air pollution.

“As the climate warms, warmer air moving in over a cold snowpack could create additional opportunities for inversions,” said Paul Gross, a retired meteorologist formerly with WDIV.

A 2016 study found that winter temperature inversions and summer heatwaves, both of which can lead to extreme pollution events, increased 50% over the last 60 years in mid-latitude regions like the United States.

“For the last at least 60 years we have data for, we can clearly see a trend of increasing temperature inversions in mid-latitude regions,” Shiliang Wu, an atmospheric chemist and associate professor at Michigan Technological University and co-author of the study, previously told Environmental Health News. “I believe this trend will continue in the coming decades, which will likely lead to an increase in extreme air pollution episodes.”

While PM 2.5 pollution was widespread during this past week’s atmospheric inversion and during last summer’s wildfire smoke, Riley said it can often be highly localized, varying significantly between ZIP codes. He’s currently working with community groups in Detroit and Grand Rapids to put networks of monitors in place, including 100 air quality monitors across Wayne County.

“Monitors do have a certain range… the closer you are to a source the more you’re likely to pick up that pollutant,” he said. JustAir will also be putting data from its new monitors online, to help notify residents of pollution spikes which may not be accounted for by the daily averages regulators use to issue alerts.

“We’re trying to get more attention to the unique neighborhood-to-neighborhood pollution sources that are affecting the individual residents,” he said.

Catch more news at Great Lakes Now: 

How to stay informed about air quality in Michigan

Record air pollution, Canadian wildfires prompts state to change how it issues air quality alerts

Featured image: Detroit Designs the World, Detroit Public TV