The skies above Los Angeles reveal a surprising truth about the region's air pollution. Trees and other plants emit volatile organic compounds (VOCs), which mix with human-made pollutants and contribute to summertime air pollution in the area.
UC Berkeley researchers CEE Professor Allen Goldstein, Eva Pfanerstill, and their colleagues conducted a groundbreaking study to measure the emission of VOCs above the city. They found that about 60 percent of these pollution-forming compounds are related to reactions from urban plants. Their study, published in Science, also highlights the significant influence of temperature on some human-driven VOC emissions, an effect not currently considered in emission inventories.
According to Pfannerstill, volatile organic compound emissions by plants are temperature-dependent and highly reactive in the atmosphere. Goldstein noted that their findings underscore regulators' unique challenge in controlling air quality. He mentioned, "Since VOC emissions from urban plants are so important and not controllable, we need to focus more on reducing emissions of the chemicals they react with from vehicles and other fossil fuel-related sources that lead to high concentrations of smog on hot days."
With the ongoing climate change, the frequency of hot days is rising, making it increasingly essential to understand how temperature affects VOC emissions and SOA (secondary organic aerosol) formation. These findings will be crucial for developing effective regulation strategies to uphold air quality in urban areas.
The complete study and a related perspective article are available online in Science. You can learn more about Professor Goldstein and Pfannerstill's research on the Berkeley Rausser College of Natural Resources website.