On-road vehicle emissions

Key points

  • From 2001 to 2012, estimated emissions from New Zealand’s on-road vehicles decreased for carbon monoxide (39 percent), nitrogen oxides (36 percent), PM10 (25 percent), PM2.5 (26 percent), and volatile organic compounds (49 percent).
  • These decreases occurred despite an increase in vehicle use of 11 percent during the same period.

Transport emissions and air quality

Emissions from transport sources include nitrogen oxides, carbon monoxide, sulphur dioxide, particulate matter, and volatile organic compounds. Nationally, on-road vehicles are the most significant source of PM10 emissions from transport (Kuschel et al, 2012). This excludes off-road vehicle emissions such as shipping, rail, aviation, and farm and construction vehicles.

National indicator: Estimated emissions from on-road vehicles down from 2002

Estimated pollutant emissions (using modelling) from on-road vehicles have decreased over the past 10 years, despite an increase in vehicle kilometres travelled (11 percent). Emissions include those from vehicle exhaust and brake and tyre wear (see figures 20–24).

All the key pollutants from on-road vehicles were estimated to have decreased from 2001 to 2012:

  • carbon monoxide, down 39 percent
  • nitrogen oxides, down 36 percent
  • PM10, down 25 percent
  • PM2.5, down 26 percent
  • volatile organic compounds, down 49 percent.

Figure 20

This graph shows Carbon monoxide – on-road transport emissions 2001–12.

This graph shows carbon monoxide – on-road transport emissions 2001–12. Visit the data files page for the full breakdown of the data.

Figure 21

This graph shows Nitrogen oxides – on-road transport emissions 2001–12.

This graph shows nitrogen oxides – on-road transport emissions 2001–12. Visit the data files page for the full breakdown of the data.

Figure 22

This graph shows Particulate matter – on-road transport emissions 2001–12.

This graph shows particulate matter – on-road transport emissions 2001–12. Visit the data files page for the full breakdown of the data.

Figure 23

This graph shows Volatile organic compounds – on-road transport emissions 2001–12.

This graph shows volatile organic compounds – on-road transport emissions 2001–12. Visit the data files page for the full breakdown of the data.

Figure 24

This graph shows Vehicle kilometres travelled 2001–12.

This graph shows vehicle kilometres travelled 2001–12. Visit the data files page for the full breakdown of the data.

Improvements in our vehicle fleet and fuel quality have resulted in reduced emissions from on-road vehicles between 2001 and 2012. These reductions may have contributed to the national decrease in PM10 concentrations between 2006 and 2012.

This reduction in PM10 concentrations due to reductions in estimated transport emissions, is also supported by the small number of council PM10 monitoring sites located close to busy transport locations, which also showed decreasing PM10 concentrations over the same period – for example, Khyber Pass Road and Queen Street in Auckland, and Wellington Central.

See weather conditions for other factors that contribute to concentrations.

See About the indicators for more information on this indicator.

Published by - Mfe and Statistics
Reviewed:
16/05/14