The Shutdown Brought Bluer Skies but More Nighttime Ozone to the Inland Empire


Air quality improvements lead to unique atmospheric chemical behavior.

Since social distancing measures to prevent COVID-19 have emptied freeways, businesses and beaches, Southern Californians have been treated to dazzling blue skies and the fluffiest, whitest clouds imaginable.

The reason? Staying at home reduces emissions of nitrogen oxides, or NOx, which reduces air pollution. One UC Riverside air quality researcher thinks that’s both good news and bad news. To maintain our cleaner air and slow climate change by reducing pollutants, some of the shutdown’s lifestyle changes, such as teleworking, need to continue long after we’ve vanquished the pandemic.

Cesunica Ivey is an assistant professor of chemical and environmental engineering at UC Riverside. She has been studying how air pollution exposure varies over time for residents across inland Southern California. Her group uses both field and modeling approaches to answer questions related to high-risk microenvironmental exposure and environmental injustices. She is currently leading a collaborative study on the effects of meteorology and climate on ozone and fine particulate pollution in the South Coast Air Basin, which includes portions of Los Angeles, Riverside, and San Bernardino counties, and all of Orange County.

Ivey said NOx is useful for understanding air quality because it is directly emitted from the pollution source. There is thus a direct relationship between the pollutant source and its concentration in the atmosphere. Other pollutants form in the atmosphere through chemical reactions and require a few more steps to trace to the source.

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Image via University of California Riverside