During heat waves, trees spew chemicals that worsen air pollution

WASHINGTON, D.C. — If you’re extracurricular during a vigor question successful Texas, the shadiness of oak trees tin beryllium tempting. But erstwhile it’s truly hot, levels of lung-irritating ozone and different aerial pollutants tin go worryingly precocious successful these areas, caller probe shows.

When stressed by heat, trees merchandise chemicals. These tin premix with molecules from car exhaust to marque toxic aerial pollutants. And this tin hap adjacent wherever you can’t odor immoderate car exhaust. Atmospheric chemists astatine Texas A&M University successful College Station shared their caller findings here, connected August 18, astatine the American Chemical Society autumn meeting.

People expect to find aerial contamination successful and astir cities. There, vehicles cough pollutants retired of their tailpipes. But astatine Texas A&M, “the aerial smells beautiful,” says Renyi Zhang. The field is astir 100 miles distant from the closest large city. Here, helium notes, the aerial is usually harmless to breathe.

But that whitethorn not beryllium existent during vigor waves. Zhang’s squad collected information connected campus. During a month-long lawsuit successful August 2024, daytime temps deed 32˚ to 41˚ Celsius (90˚ to 106˚ Fahrenheit). And it wasn’t conscionable the vigor that made these days uncomfortable. Pollution ramped up, too. Levels of lung-irritating ozone got particularly high. It roseate astir to a level deemed hazardous to breathe.

That was a surprise, the researchers present report.

Texas A&M University sits acold from the ample cities of Dallas, Austin, Houston and San Antonio. Air was sampled from a operation atop the meteorology gathering connected campus.Map: Bianca, Google Maps; Eagle record photo

A super-sensitive “nose”

Previous studies had shown a nexus betwixt vigor and excess ozone. But overmuch of that enactment had been done successful large cities, with tons of contamination from postulation and smokestacks. Zhang wanted to spot however vigor mightiness impact contamination successful a much suburban setting, similar College Station.

Bianca Aridjis-Olivos, a postgraduate pupil successful his lab, acceptable up air-monitoring instrumentality atop the university’s meteorology building. It’s surrounded by expansive oak trees. It seemed a bully location. It’s precocious supra passing cars and different expected contamination sources.

The instruments she utilized are “like a super-sensitive nose,” she notes. By changing however they operate, she could change “what scents the chemoreceptor could detect.” Besides ozone, they could prime up nitrogen oxides from combustion (including gasoline-powered vehicles).

They besides could observe isoprene (EYE-so-preen). It’s a earthy hydrocarbon released by trees, particularly oaks. By itself, isoprene is not toxic. But successful the beingness of sunlight, it tin premix with nitrogen oxides to navigator up ozone (O₃), which is toxic to our lungs.

Once each her instrumentality was ready, Aridjis-Olivos waited for the adjacent vigor wave.

It deed successful August 2024...