Air quality standards and guidelines

Standards and guidelines set limits on the amount of a pollutant in air to provide a minimum level of health protection across the population. The limits can be stated as a short term average (1-hour) to protect against acute effects from exposure to high levels of an air pollutant or as a long term average (annual) to protect against chronic effects from life time exposures, such as decreased life expectancy. While standards and guidelines provide a minimum level of health protection, there are some pollutants, such as PM2.5, for which there is no reliable evidence of a zero-harm threshold.

Regional target: Proposed National Resources Plan – Schedule L1: Regional ambient air quality targets

National standard: National Environmental Standards for Air Quality (2004) – Schedule 1

National guideline: Ambient air quality guidelines (2002). Ministry for the Environment.

World Health Organisation guideline: World Health Organization air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide. Global update 2005. Summary of risk assessment (2006).

Limit Averaging period Permissible exceedances per year Assessment criteria
PM10
33 μg/m3 24-hour 0 Regional target
50 μg/m3 24-hour 1 National standard
13 μg/m3 Annual NA Regional target
20 μg/m3 Annual NA National guideline
PM2.5
17 μg/m3 24-hour 0 Regional target
25 μg/m3 24-hour 3 WHO guideline
7 μg/m3 Annual NA Regional target
10 μg/m3 Annual NA WHO guideline
Carbon monoxide (CO)
7 mg/m3 8-hour moving 0 Regional target
10 mg/m3 8-hour moving 1 National standard
20 mg/m3 1-hour 0 Regional target
30 mg/m3 1-hour 0 National guideline
Nitrogen dioxide (NO2)
132 μg/m3 1-hour 0 Regional target
200 μg/m3 1-hour 9 National standard
66 μg/m3 24-hour 0 Regional target
100 μg/m3 24-hour 0 National guideline
40 μg/m3 Annual NA WHO guideline

NO2 passive tube site types

Site type Description (NIWA)
Urban background A site located within an urban area that is more than 400 m from any road with Annual Average Daily Traffic (AADT) > 10,000
Roadside A site located within 200 m of the centreline of any road with AADT > 10,000
Peak A site with one or more of the following:
  • Located within 200 m of the centreline of more than one road with AADT > 10,000 is classed as ‘multiple roadside’
  • Located within 100 m of the centre of any roundabout or signalised intersection is classed as ‘intersection’
  • Located in a street with AADT > 5,000 and building heights > 8 m on both sides is classed as ‘street canyon’
  • Suspected to be influenced by atypically high volumes of diesel exhausts (from buses, trucks, rail, aviation, maritime or industrial sources) is classed as ‘high diesel’.