Time to get rid of old, polluting school buses

It's time to question why the oldest, most polluting buses in the Wellington region are used to transport children to school each day.

It's become the norm for operators to reserve their most clapped-out buses for schoolchildren mainly because they get a special exemption from NZ Transport Agency bus rules.

NZTA stipulates bus operators must remove vehicles from their fleet when they are 20 years old. But under a schoolbus exemption, operators can keep them in service for a further six years if they are used as schoolbuses.

The rationale is that children don't mind travelling around in dilapidated old buses, and the buses are used for only a few hours a day, so they are less likely to break down continuously.

The problem is that 20-year-old schoolbuses don't meet any emissions standards, and spew out huge amounts of diesel fumes that contain a toxic brew of air contaminants. A 20-year-old bus can emit 10 to 100 times as many fumes, including heavy metals, nitrogen oxide and soot particles, than cleaner alternative buses.

The soot particles in diesel fumes have been recently classified as carcinogenic by the World Health Organisation - in the same category as arsenic, asbestos and second-hand smoke. These particles are so tiny they can lodge deep inside the lungs, enter the bloodstream and can contribute to lung cancer, asthma, heart disease and other respiratory diseases.

The WHO experts who reassessed diesel fumes concluded that children are most at risk from diesel fumes, as their lungs and other organs are still developing.

This means children who travel on older schoolbuses are being routinely exposed to carcinogenic compounds in diesel fumes that can increase their risk of developing asthma and other respiratory and health problems.

American researchers have discovered that vehicle pollution inside old schoolbuses can be considerably worse than pollution outside a bus.

In 2001 American researchers measured vehicle pollution inside old Los Angeles schoolbuses, and found to their astonishment that the pollution inside them was five times higher than pollution outside. The pollution levels were highest in the back of a bus, especially when the windows were closed, and increased when a bus was going uphill or idling.

The researchers concluded that children who rode in old schoolbuses for many years were likely to be exposed to significant and potentially hazardous levels of toxic diesel exhaust - 30 times higher than is considered acceptable by government agencies. Their study has been replicated several times in the United States, with similar results, and has prompted campaigns there to improve the quality of schoolbuses. Many American states now require old buses to be removed from the fleet.

Alternatively, they must be retrofitted with devices that control air pollution, such as diesel particulate filters, or use alternative clean-burning fuels.

Many states also prohibit schoolbuses from idling for more than three minutes.

I'm not aware of any similar study to measure vehicle pollution inside schoolbuses here, but it's safe to assume that 20-26-year-old schoolbuses would emit similar levels of diesel soot particulates and other hazardous pollutants.

Now that we know that diesel soot particles can cause cancer, and that children are particularly sensitive to these carcinogenic compounds, we cannot in all conscience continue to allow our children to travel to school in dirty, polluting buses every day.

To protect their health, we need to remove the NZTA exemption for schoolbuses, and retire all buses from service after 20 years, with no exceptions.

Agencies that contract schoolbuses, like the Greater Wellington Regional Council and Ministry of Education, must insist bus operators use clean, non-polluting buses that meet modern emission standards. At the very least, they should require operators to retrofit old schoolbuses, or use clean-burning fuels.

And we need new rules around the idling of schoolbuses near schools. A lot of drivers keep bus engines running at schools while waiting to pick up students, because old buses can take some time to get started. So we also need new rules that stipulate that schoolbuses may not idle for more than a few minutes near schools.

Measures such as these can ensure that children in the Wellington region are not exposed to their biggest dose of air pollution on their commute to and from school.