Tuning cars a key to reducing New Zealand's air pollution

Keeping your car in tune could do more to help reduce motor vehicle pollution than fitting catalytic converters, says the National Centre for Climate–Energy Solutions.

Air quality scientist Dr Gerda Kuschel from the National Institute of Water & Atmospheric Research says that while catalytic converters can reduce vehicle emissions, in some cases by up to 90%, they do have their limitations, and tuning your car – and re-tuning it every 6 months – is just as important for improving urban air quality.

The differences between emissions from well- and badly maintained vehicles of any age are much larger than the impacts of emission control technology and vehicle age.

Vehicles contaminate the atmosphere through fuel combustion, fuel evaporation, stirring up road dust, and wear and tear from brake linings and tyres.

“By simply maintaining your car you can significantly reduce vehicle emissions and maximise fuel economy. This is one area where every motorist can help.”

Dr Kuschel says the main reason why catalytic converters do not have a bigger impact in controlling urban air pollution in New Zealand is that most trips are short and the catalyst has not had sufficient time to operate properly. The converters need about 10–15 minutes to warm up, and are currently available only for petrol models and only for exhaust emissions, and they must be maintained. They also have no effect on fine particulate matter that settles in the lungs.

“Catalytic converters are basically an after-treatment solution. They don’t treat the cause of the emissions, which is that petrol-fuelled internal combustion engines operate inefficiently. They can have a significant effect on reducing emissions, such as carbon monoxide, nitrogen oxide, volatile organic compounds and sulphur dioxide, but we need to consider their limitations.”

All petrol vehicles currently entering New Zealand for sale are now equipped with catalytic converters, and manufacturers are working on special trap systems to limit particulate emissions from diesel vehicles.

Other methods for controlling or managing vehicle emissions include using cleaner-burning fuels, using new engine technologies, and improving traffic flow.

Motor vehicle use is now generally recognised as the source of more air pollution than any other single activity in cities around the world. The Ministry of Transport has recently assessed that vehicle emissions in New Zealand result in up to 400 premature deaths per year.