Particulate Matter (PM10 and PM2.5)
Particulate matter is made up of very small particles that can be breathed deep into the lungs.
- PM10 particles smaller than 10 microns
- PM2.5 particles smaller than 2.5 microns, which pose the greatest risk to human health
Nelson has monitored PM10 for more than 20 years, and PM2.5 since 2018. These particles mainly come from:
- domestic heating, especially wood burners
- some industrial activities
PM10 is regulated under the National Environmental Standards for Air Quality (NESAQ), while PM2.5 is increasingly recognised as a key health concern under World Health Organisation (WHO) 2021 Guidelines.
Nitrogen Dioxide (NO₂)
Nitrogen dioxide (NO₂) mainly comes from motor vehicle emissions, with smaller contributions from industrial sources.
While past winter monitoring in Nelson complied with national standards, new WHO guidelines show that even low levels of long‑term exposure can affect health. Council is continuing to investigate how Nelson’s annual NO₂ levels compare with these updated guidelines.
