KALAMAZOO, Mich. – City air sensors have detected potentially dangerous levels of hydrogen sulfide pollution in the air for more than three years, and experts are concerned about chronic or lifelong exposure to the gas over a period of years.
Levels of the gas measured by sensors over a three-year period in Kalamazoo consistently exceeded 1.4 parts per billion, a concentration that could be dangerous to sensitive groups with lifetime exposure, according to Environmental Protection Agency guidelines.
For some sensors, the measured amount has risen many times over this level over the years.
The sensor near Ascension Borgess shows average monthly levels that do not fall below 2 parts per billion for 31 consecutive months starting in September 2019 through March 2022, which is all the data available for this sensor. The sensor at Gull Road and Riverview Drive was at or above 4.6 parts per billion from September 2019 to August 2022, the most recent data available.
Sensors placed near urban infrastructure also show elevated levels. A sensor in the wastewater treatment plant’s fine-screen building was at or above 7.3 parts per billion for those 31 months. The sludge storage facility’s sensor was at or above 5.6 parts per billion for the same 31 months.
Justin Colacino, an associate professor in the University of Michigan’s Department of Environmental Health Sciences, said it’s troubling that overall readings don’t appear to be decreasing over time and remain above the 1.4 parts per billion level.
Exceeding that concentration suggests that the most vulnerable people could have adverse health effects if exposed over a period of years, Colacchino said.
A state health department spokesman, responding to concerns about the readings, said the levels did not necessarily mean health effects would occur.
Colachino said that exceeding the chronic reference level does not guarantee that everyone will get sick. But you start to worry about the most vulnerable people, he said, like younger or older people or those with pre-existing lung conditions like chronic obstructive pulmonary disease.
“This is a chronic scenario,” Colacchino said, pointing to more than three years of elevated gas measurements, with the first readings in September 2019.
“Because it’s chronic, the health effects of these chemicals tend to accumulate over time, so a smaller dose can start to cause problems,” Colachino said.
As the air sensors came online in early 2019, they all showed levels well above 1.4 parts per billion. At a sensor in Gull and Riverview, the average level was about 19 parts per billion in 2020 and about 14 parts per billion on average in 2021.
The number of 1.4 parts per billion is an approximate threshold below which exposure to it in humans through daily inhalation is likely to be without significant risk of harmful effects over a lifetime, according to the Environmental Protection Agency.
“Under this scenario, exposure appears to have continued since at least September 2019 and, without mitigation efforts, is expected to continue,” Colacino said.
Chronic exposures can be thought of as exposures that last for a long time, for much of an individual’s life, he said.
Toxicologist Brandon Reid of the Michigan Department of Health and Human Services told MLive/Kalamazoo Gazette in October 2021 that the concentrations found in the air exceeded the long-term exposure reference value set in the EPA reference concentration of 1.4 parts per billion.
“We’re seeing short-term levels that are above long-term benchmarks,” Reid said at the time, and that researchers need to look further to determine the potential impact.
Lifetime exposure levels to the chemical that fall below 1.4 parts per billion are unlikely to be associated with adverse health effects, Reid said at the time.
The raw data from the sensor was recently made public by the City of Kalamazoo on the Odor Task Force page on the city’s website.
Unfortunately, public notification is not required by law if certain levels are exceeded, Colacino said.
Colacino and others in his lab study how chemicals in the environment promote the development of chronic diseases such as cancer. They do experiments with cells and mice to determine the effects of chemicals and conduct human studies to determine the health risk of different concentrations of chemicals, he said.
His degrees include a doctorate in environmental health sciences from the University of Michigan School of Public Health, a master’s in statistics from the University of Michigan and a master’s in public health from the University of Texas at Dallas School of Public Health, he said.
Human studies show that the respiratory tract and nervous system are the most sensitive targets of hydrogen sulfide toxicity, according to the Centers for Disease Control and Prevention. Exposure to low concentrations of hydrogen sulfide can cause eye, nose, or throat irritation. It can also cause breathing difficulties in some asthmatics, the agency said.
Denise Trabic-Poynter, a former environmental manager at DuPont with a background in chemical engineering and occupational health who now volunteers with the Sierra Club in Michigan, noted how guidelines for public exposure to chemicals are much lower and therefore more protective from exposure to workplace guidelines.
“Part of it is because when you live there, you can’t get away from it,” she said.
It suggested efforts to keep gas levels lower and more protective than some of the levels seen in recent months. She mentioned the possibility that a local government could set a level that would trigger action by the city or the gas source once that level is exceeded.
She said there are concerns about the potential for chronic exposures based on the length of time the levels are detected.
In addition to sensors, gas can also be detected by smell.
Resident Jaylen Bean, 19, works at the Walgreens at the corner of Riverview Drive and Gull Road.
“I’ve been smelling it for years,” Bean told MLive/Kalamazoo Gazette. He thought it was a dumpster nearby. It makes him wary to learn that the smell is probably industrial gas.
“If it’s dangerous, maybe we shouldn’t have so many people in the area,” Bean said.
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