The Institute of Environmental Science and Research (ESR) has changed its name to the New Zealand Institute for Public Health and Forensic Science (PHF Science) as of 1 July 2025. The new website address is www.phfscience.nz. Visitors will automatically be redirected to the new address. Please check and update any links and bookmarks after this change.

Factsheet on WHO AQG - Health Effects of Long-Term Exposure to NO2 and O3

Please note: As of 1 July 2025, the New Zealand Institute for Public Health and Forensic Science (PHF Science) is the new name for the Institute of Environmental Science and Research (ESR). Research and reports published prior to this date may reference the organisation’s former name.

Summary

In 2021, the World Health Organisation (WHO) published revised recommendations for ambient air quality (WHO 2021). To support this update, WHO published a review paper in 2020 evaluating the best available evidence on the effects of long-term exposure to nitrogen dioxide (NO2) and ozone (O3) (Huangfu and Atkinson 2020). Specifically, the research published updated quantified risk ratios for exposure to NO2 and all-cause and cause-specific premature mortality (people dying earlier than they otherwise would have). 1

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