economics Nature Is Weird

Most pollution makes the flu worse, but ground-level ozone might actually protect you from getting infected.

March 26, 2026

Original Paper

Subtype-specific associations between ambient air pollution and influenza virus infection: a nationwide case-crossover study in China

Shimeng Cai, Xin Liu, Bin Zhu, Dayan Wang, Hao Lei

SSRN · 6447968

The Takeaway

A nationwide study in China discovered that while particulates like PM2.5 and gases like NO2 increase influenza rates, higher levels of ozone—usually considered a dangerous pollutant—were associated with a significant decrease in laboratory-confirmed flu cases, likely due to its disinfectant properties in the environment.

From the abstract

With the advancement of industrialization and the acceleration of urbanization, air pollution has become a major environmental health issue worldwide. However, the subtype-specific associations between air pollution and influenza virus infection remains unclear. In this nationwide individual-level case-crossover study, conditional logistic regression models combined with distributed lag models were applied to quantify the associations between exposure to PM2.5, PM10, O3, CO, NO2, SO2 and influen