“If you want a chemical reaction to go faster, you have to add heat,” said Johns Hopkins University atmospheric air pollution researcher Peter DeCarlo, who is working on an initiative to use vanes to measure emissions in Louisiana’s petrochemicals corridor. “On warmer days, same idea,” he said.

Air pollution increases as temperatures increase, increasing the harm caused by global warming. That’s one reason why cities and counties across the eastern United States, hit by a heat wave this week, are issuing air pollution warnings.

Three days ago, it warned that ozone levels in New York City were “unhealthy for sensitive groups”. Detroit and Chicago also issued air quality warnings this week. Drivers in Ohio, Michigan, Kentucky and Indiana are urged to avoid refueling before 8 p.m., and to carpool or avoid driving as much as possible to reduce smog.

Prof. that poor air is related to atmospheric chemistry. DiCarlo said his van took two New York Times journalists on a ride to the South Bronx, East Harlem and Midtown. Pollution from burning fossil fuels reacts with heat and sunlight to form ground-level ozone. Higher temperatures turbocharge that process.

Formaldehyde emissions, which can come from a variety of sources, such as forest fires and household products, rise with higher temperatures. “The same chemistry that creates high levels of ozone also creates additional hazardous air pollutants, such as formaldehyde,” Professor DiCarlo said.

Local hot spots can sometimes be found. For example, in some blocks in Manhattan, formaldehyde levels were double that of surrounding areas, likely due to dirty burning caused by nearby broken appliances.

Heat pollution is a growing concern worldwide. Health hazards from extreme heat aren’t the only effect of record-breaking temperatures. According to the World Meteorological Organization, air pollution will also increase as temperatures rise In a statement Last year.

“Climate change and air quality cannot be considered separately,” Meteorological Organization Secretary-General Petteri Talas said at the time. “They go hand in hand and must be tackled together to break this vicious cycle.”

Breathing in elevated levels of formaldehyde and ozone has been linked to respiratory irritation and inflammation, reduced lung function, and problems with preventing and controlling asthma attacks. Exposure is particularly high in people with lung diseases such as asthma or chronic bronchitis, said Kiev Nachman, an environmental-health and risk assessment researcher at the Johns Hopkins University and co-leader of the Mobile Monitoring Initiative.

Coincidentally this week, as New York was hit by a heat wave, the research team had its pollution-sniffing vans in the city to demonstrate their technology.

Professor Nachman said that while formaldehyde is carcinogenic to humans, the cancers are primarily expected from long-term exposures, not from temporary increases.

It’s important to recognize that chemical exposures don’t happen all at once, and that we’re constantly exposed to groups of chemicals that can work together to harm our health, he said. “Hot days can create situations where people are breathing in many harmful chemicals at the same time,” Professor Nachman said. “Formaldehyde and ozone are perfect examples.”

A van is set to return to Louisiana later this year to measure 45 pollutants from its petrochemical industry, part of a project funded by Bloomberg Philanthropies’ Beyond Petrochemicals campaign. In an initial peer review A study published this monthResearchers found emissions of ethylene oxide, a cancer-causing gas used in plastic production, were much higher than previously known.

Researchers operating the van, a high-tech lab-on-wheels built by environmental measurement technology company Aerodyne, can see pollution levels in real time and try to determine their source. “It’s like a video game,” Professor DiCarlo said. “We can measure everything at once.”

Blackie Migliosi Contributed report.