A team from the Rutgers School of Public Health have examined the health and environmental impact of wildfire smoke from Canadian forest fires on the northeastern U.S., finding that temperatures in the region fell by around 3°C, making air quality even worse.
Using real-time instruments, the team studied the physical and chemical properties of smoke from the 2023 wildfires that were taking place 800km away, and examined its impact on sunlight and temperature in the New Jersey/New York area.
The researchers looked at how the smoke particles interact with light—specifically how much light they scatter or absorb. They found that the smoke blocked so much sunlight that it caused a strong cooling effect at the ground level, reducing ground temperatures by about 3°C.
This cooling effect is known as negative radiative forcing but has been labelled ‘global dimming’, the opposite of global warming. The researchers speculate that in big cities, the drop in air temperature can reduce the urban heat island effect, which normally cause cities to stay hotter than surrounding areas. This slows down natural air movement, meaning wildfire smoke and other air pollutants stay near the ground longer.
Philip Demokritou, senior study author and Henry Rutgers chair and professor of nanoscience and environmental bioengineering at the Rutgers School of Public Health and the School of Engineering said: ‘With all you hear about the negative consequences of global warming, you might think the cooling would be good. But cooler temperatures are equally bad as global warming. This effect on microclimate can disrupt the hydrological cycle, trap other toxic air compounds and increase human exposure levels.’
In February, the same team published research that revealed that during the fire event, 9.2 mg of smoke particles was deposited in the lungs of people in the area.
Georgios Kelesidis, an assistant professor at the Rutgers School of Public Health and lead author of the study said; ‘The wildfire particulate matter that arrived in the New Jersey and New York City area on June 7 contained mostly brown carbon particles that had not been photobleached completely despite covering a distance of about 800 kilometers.’
Demokritou added: ‘This study documents for the first time the effect of wildfire nanoparticles on the microclimate of megacities. Such ambient air temperature reductions may exacerbate the urban heat island effect and limit the natural ventilation of megacities, exacerbating the exposure to air pollution.’
The full research can be read here.
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