Cleaner transport

There are a wide range of air pollutants in traffic emissions. We measure nitrogen dioxide (NO₂) levels as the main indicator of traffic-related air quality because it’s a specific marker for traffic exhaust emissions and also has harmful health impacts.

Nitrogen dioxide mainly affects the respiratory system (lungs). It can increase the risk of infection, aggravate asthma and affect lung development in children.

We are also monitoring black carbon, which is an indicator of harmful particles from traffic exhaust at our Wellington central monitoring station.

Levels of nitrogen dioxide and black carbon are highest closest to roadsides, but pollutant levels vary greatly depending on traffic intensity and distance from intersections (where traffic starts and stops frequently).

Traffic emissions can build up on inner city streets where there are tall buildings on either side of the road and when there is a high number of diesel vehicles.

We are developing an indicator to track trends in traffic-related harmful emissions near roadsides and in residential areas away from busy roads. To see the latest results from our NO₂ passive diffusion tube network, see our annual report. 

• Find out about active and sustainable transport options for your commute to work or school
• Consider electric vehicles which have no harmful exhaust emissions
• Tune and service your vehicle regularly to avoid smoky high pollution exhaust emissions