Drive-by emissions tests – carbon monoxide levels high 19 May 2003
Preliminary test results for carbon monoxide (CO) from the drive-by emissions testing programme conducted throughout the
Auckland region during April show that Auckland’s CO emissions are high compared to US cities and that 50% of emissions
come from the worst 10% vehicles.
The results show the number of cars tested at each site, and the average carbon monoxide (CO) reading.
The percentage of vehicles that are good, fair or poor is also given for each site.
The average carbon monoxide reading can be compared to results from similar surveys in Los Angeles and Denver:
Region Year Average CO level
LA, California 2001 0.44%
LA, California 1999 0.58%
Denver 2001 0.34%
Denver 1996 0.53%
Auckland 2003 0.71%
Carbon monoxide is an invisible toxic gas. High CO emissions mean that a car is badly maintained, or has broken emission
control equipment.
The results from California and Denver illustrate the dramatic decrease in CO emissions over several years due to the
increasing prevalence and efficiency of catalytic converters.
Nitrogen oxides and hydrocarbons were also measured in the drive-by emissions testing programme:
Region Year Average CO Average HC Average NO
Los Angeles 2001 0.44% 125 ppm 411 ppm
Denver 2001 0.34% 112 ppm 483 ppm
Auckland 2003 0.71% 331 ppm 602 ppm
More detailed results will become available when NIWA provides a full report to the Auckland Regional Council by August
2003.
This report will include analysis of the effect on emissions of vehicle age and fuel type. The preliminary results show
some differences between the various sites tested. This may be because of differences in the type of vehicles (age,
fuel, etc).
The results could also be affected by different driving conditions at the different test sites. For example cars produce
higher emissions while accelerating.
A remote sensor was stationed at 14 sites on different days, and collected vehicle emissions data from more than 30,000
vehicles. Drivers were able to view a reading that indicated if their vehicle’s emissions were “good”, “fair” or “poor”.
When the readings were plotted on a graph, was clear that the worst 10% vehicles had created 50% of the emissions.
“We will be sharing the results of the tests with the Government,” said ARC chairperson Gwen Bull.
“While driver education, such as through 0800 SMOKEY had a positive effect, we believe that the only way to get the
small percentage of vehicles who are producing the most pollution is to regulate to ensure that they must clean up their
act. This is only fair on everyone else,” said Cr Bull.
“Our concern is to clean the air for Aucklanders in the most effective way possible. The effects of vehicle pollution
on our health are significant. The drive-by emissions testing is helping us to gain more information.
“We are encouraged by Judith Tizard’s work in this area and urge her to keep the pressure on, for the health of
Aucklanders.”