Heatwave updates: 100 million people in US remain under advisory

Two vans loaded with precision instruments drove the streets of New York and New Jersey in the heat earlier this week, searching for toxic chemicals in the air.

They detected spikes in methane, a powerful greenhouse gas, likely due to leaks or buses running on natural gas. They found plumes of nitrous oxide, likely from sewage. And along the way, they recorded high levels of ozone, the main ingredient in smog, as well as cancer-causing formaldehyde – both of which form easily in hot weather.

Bottom line: the streets are dotted with pollution hot spots. And heat worsens pollution.

“If you want a chemical reaction to happen faster, you add heat,” said Peter DeCarlo, an air pollution researcher at Johns Hopkins University who leads a project to use the vans to measure the emissions along Louisiana’s petrochemical corridor. “On warmer days, it’s the same idea,” he said.

Air pollution increases when temperatures rise, worsening the damage caused by global warming. That’s one reason why cities and counties in the eastern United States hit by a heat wave this week have issued air pollution alerts.

For the past three days, New York City has warned that ozone in the city is at levels that are “unhealthy for sensitive groups.” Detroit and Chicago also issued air quality alerts this week. Drivers in Ohio, Michigan, Kentucky and Indiana were asked to avoid refueling before 8 p.m. and to carpool or refrain from driving as much as possible, to reduce fumes .

Bad air is linked to atmospheric chemistry, professor. DeCarlo said, as his van toured the South Bronx, East Harlem and Midtown with two New York Times reporters. Pollution from burning fossil fuels reacts with heat and sunlight, forming ground-level ozone. Higher temperatures turbocharge this process.

Formaldehyde emissions, which can come from sources as diverse as wildfires and household products, also increase with rising temperatures. “The same chemistry that generates high levels of ozone also produces additional dangerous air pollutants, such as formaldehyde,” explains the professor. » said DeCarlo.

Local hot spots can sometimes be observed. For example, in some Manhattan neighborhoods, formaldehyde levels were double those in surrounding areas, likely due to particularly dirty combustion caused by faulty equipment nearby.

Peter DeCarlo inside one of the vans.Credit…Blacki Migliozzi/The New York Times

The link between heat and pollution is a growing concern globally. Adverse health effects from extreme heat are not the only result of record-breaking temperatures. Air pollution also increases when temperatures rise, the World Meteorological Organization said in a report last year.

“Climate change and air quality cannot be treated separately,” Petteri Taalas, secretary general of the meteorological organization, said at the time. “They go hand in hand and must be addressed together to break this vicious cycle. »

Breathing high levels of formaldehyde and ozone has been linked to problems such as respiratory irritation and inflammation, reduced lung function, and difficulty preventing and controlling asthma attacks. Exposure is of particular concern among people with lung diseases like asthma or chronic bronchitis, said Keeve Nachman, an environmental health and risk assessment researcher at Johns Hopkins and co-leader of the mobile monitoring effort. .

Coincidentally, this week, as New York was hit by a heatwave, the research team deployed their anti-pollution vans around the city to demonstrate their technology.

Prof. Nachman said that even if formaldehyde was carcinogenic to humans, the cancers would be mainly due to long-term exposures and not temporary increases.

It’s also important to recognize that chemical exposures don’t happen once at a time and that we are constantly exposed to groups of chemicals that can act together and harm our health, he said. “Hot days can create situations in which people breathe many harmful chemicals simultaneously,” the professor said. said Nachman. “Formaldehyde and ozone are perfect examples.”

One of the vans is expected to return to Louisiana later this year to measure up to 45 pollutants from its petrochemical industry, as part of a project funded by Bloomberg Philanthropies’ Beyond Petrochemicals campaign. In a first peer-reviewed study published this month, researchers found much higher emissions of ethylene oxide than previously thought.

Researchers piloting the van, a high-tech laboratory on wheels built by environmental measurement technology company Aerodyne, can see pollution levels in real time and even track plumes to try to determine their source. “It’s a bit like a video game,” explains the professor. » said DeCarlo. “And we are able to measure everything at once.”

Blackie Migliozzi reports contributed.

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