Ozone gas and Earth have a complicated relationship. In the atmosphere, ozone absorbs the sun’s harmful radiation before it reaches us. But ground-level ozone—produced by chemicals and by burning fuel—can cause serious health problems. Now, researchers have found that ozone could also make the flu less dangerous. Linwei Tian, an environmental epidemiologist at the University of Hong Kong School of Public Health, spoke to Harvard Public Health.
Why study this topic?
I have long been aware of the so-called paradoxical ozone associations: Ozone triggers health problems, particularly for children, the elderly, and those who have chronic diseases, but there are also numerous reports showing the beneficial effects of ozone on certain diseases, such as asthma. Recently, scientists reported that ozone reduced influenza transmissibility in subtropical Hong Kong. We wanted to see if this was true in more temperate climates, like in the U.S.
What did you find?
Ambient ozone increases the risk of exacerbating chronic lung diseases, but it decreases the risk of influenza. It diminishes the severity of influenza virus infections, and there is less injury to the lungs. Ozone’s oxidizing power may act like a virucide, but more likely, it primes your immunity against viral infection. Reducing ozone is not necessarily the most protective of public health.
What would you like to see happen based on the results of this study?
These findings warrant further research to corroborate the cause-effect relationship between ozone and influenza. Close to 100 percent of the population is susceptible to the flu, unlike asthma and other lung problems. We hope to ease the threat of seasonal and novel influenza epidemics. When countries and cities review and update environmental standards for ozone, they should conduct a holistic health risk assessment.
—Leah Samuel
(Study in Nature Communications, May 2024)
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