Through the window of Circulo de Amigos Child Care Center in Minneapolis, Tania Rivera Perez pointed to the drifts of gray smoke in the air across Cedar Avenue.
The daycare and preschool opened in 2015 in the East Phillips neighborhood, across the street from a foundry and asphalt plant. The center is certified as an outdoor classroom, and kids mostly learn and play outside in warmer months. Sometimes, though, parents ask during drop-off, "What's that smell?"
"We know that there [are] industrial plants here, but we weren't really sure what exactly they were doing," Rivera Perez said. "We would see fumes, of course. And that definitely made us wonder what it was."
Now, Circulo de Amigos is one of 70 sites around Minneapolis fitted with a PurpleAir monitor. The devices measure fine particulate matter, sometimes referred to as soot. The tiny particles are easily inhaled and burrow into the lungs, which can cause heart and asthma attacks and sometimes premature death. Readings from the monitor are available in real time, on PurpleAir's website.
The monitor is part of a city-wide effort by Minneapolis to get a better picture of what, exactly, its residents are breathing in. After putting the PurpleAir sensors on homes and businesses throughout 2022, the city will add two other types of sensors this year. The new instruments are supported in part by a grant from the Environmental Protection Agency, which will detect volatile gases that can also make people sick.
While the city meets the EPA's air standards, "We've been hearing from residents in Minneapolis for a long time that they wanted more information about local air quality," said Jennifer Lansing, a senior environmental research analyst with the city's Department of Health.
Tighter air standards could be coming. On Friday, the EPA proposed lowering the limits for fine particulate pollution.
For Circulo de Amigos, the PurpleAir sensor has been a useful tool. Readings stayed relatively low after it was installed in the summer and into the fall.
"I'm at ease, knowing that we're taking extra measures to make sure that the kids have clean air here, at least at the school," she said. "If not, we know we have a backup plan [to go inside]."
Lansing said that 30 AQMesh monitors, which are on loan from the state, will be installed in the spring on lamp posts to measure aggregate levels of volatile organic compounds, or VOCs, in outdoor air. Additional sensors will pinpoint which toxic gases make up these VOCs.
Lansing said that the sensors are meant to give a broad picture of air quality, and could not be used for action against polluters.
"We would never be able to collect data and say ... these particulates came from this facility," Lansing said. "There's so many different sources of pollution in the urban area," including from cars and trucks.
In the case of East Phillips, one neighborhood leader said he hopes the new gas-detecting monitors will help to pin down releases from the two major sites — Smith Foundry and Bituminous Roadways — that he and his neighbors say have made the air smell acrid, intermittently, for years.
"We've complained for decades" about pollution from local industry, said Steve Sandberg, a resident and board member of the East Phillips Neighborhood Institute.
The neighborhood is also the site of a protracted battle over city plans for a yard for water system trucks at the former Roof Depot warehouse. Activists oppose the project, in part, over air pollution concerns.
Peter Ryan, quality manager and director of health, safety and environmental at Smith Foundry, said that "We are in compliance with all state and local requirements" for air quality.
Bituminous Roadways did not respond to a request for comment.
Hannah Sabroski, a spokeswoman for the Minnesota Pollution Control Agency, said the only enforcement action against either facility came in 2006. Smith Foundry was cited for a broken baghouse, which controls particulates, as well as "overdue performance testing and using equipment not in their permit," Sabroksi wrote. The company paid a fine and corrected the problems.
Lansing said the city continues to field smell complaints to its 311 line and sends inspectors, if necessary, to measure odors near the foundry and asphalt plant. She also said the foundry has recently expressed interest in the city's voluntary cost-share program for pollution reduction.
Sandberg said that in the past, city inspectors haven't come when the smells are strongest.
Minneapolis' testing program focuses on its green zones, or neighborhoods with a history of pollution and racial segregation. Monitors have been put in other places as well.
KJ Starr, who lives in the Seward neighborhood with her husband and four children, installed a PurpleAir monitor last summer. For years, she worried about emissions from a local landscaping business' diesel trucks.
"If you live in these weird industrial areas, it's a burden on you to figure out yourself," Starr said.
A city law passed last year has helped to cut down on truck idling. But looking at her air monitor readings during a December conversation with the Star Tribune, Starr found herself worried that particulate levels were high enough to affect medically sensitive people. She herself has asthma.
"I was hoping that I would be like oh, 'I'm just worrying, and I shouldn't worry about it'" after getting the sensor, Starr said. "And then I look at this and I'm like, it's a bummer."
Others have had a more pleasant surprise from the readings.
Daniel Swenson-Klatt, the owner of Butter Bakery Cafe at 3700 Nicollet Av., started thinking more about the air around his business when the cafe expanded outdoor seating during the COVID-19 pandemic.
Last summer, things mostly stayed clear on his PurpleAir monitor. He hopes, however, that the city will stay mindful of air pollution as it seeks to turn business corridors like Nicollet into denser, transit-oriented arteries.
"If we want to have people living in these corridors, let's also be aware we want to give them some good air quality," he said.
