Beijing's Isoprene-Emitting Trees Highlight Ozone Risks in Greener, Hotter Cities

These trees are making air quality in cities worse

Nature, Published online: 20 August 2026; doi:10.1038/d41586-026-02586-2They release compounds that contribute to ozone emissions, and rising temperatures could exacerbate the problem.

Beijing's isoprene-emitting trees highlight ozone risks in greener, hotter cities

Amid current heat waves, urban greening is once again moving to the center of public debate. Greener cities are generally expected to have cleaner air because trees capture airborne particles, absorb gaseous pollutants and cool urban neighborhoods. But trees also emit biogenic volatile organic compounds (BVOCs) that, in the presence of sunlight and nitrogen oxides (NOx), can contribute to ground-level ozone formation.

Tree selection in urban greening shapes air quality for global cities

Abstract Mitigating ozone pollution remains a pressing challenge for megacities worldwide. Biogenic volatile organic compounds (VOCs) are proposed as pivotal precursors to urban ozone formation. However, direct observational evidence is scarce and the extent of this effect across cities is unclear. Here, by combining an unprecedented eddy covariance flux dataset from Beijing with modeling analysis, we find that urban vegetation contributes over …