Lead fumes in urban air may still present an exposure risk - 29/03/2017

Air monitoring work by GNS Science has found that atmospheric concentrations of lead peak during winter in New Zealand urban centres.

Dr Bill Trompetter

Atmospheric scientist Dr Bill Trompetter with one of the many air filters that GNS Science analyses each year. Photo – Kate Whitley, GNS Science

The investigation, which analyses the makeup of tiny particles that are ubiquitous in the air, also found that arsenic levels are above national and international guidelines in a number of New Zealand urban centres.

As lead has been removed from petrol for more than 20 years, the main source of the elevated levels is likely to be the burning of old painted timber (lead) and treated timber (arsenic) in domestic fires and, consequently, the highest atmospheric levels of these substances occurs during winter in residential areas.

In some cases, atmospheric concentrations of these substances in winter have exceeded the upper guideline for human health.
 
The study suggests that sufficient quantities of contaminated timber are being burnt to potentially cause chronic illness to sections of the population.

Study leader Perry Davy of GNS Science said the most likely source of the treated timber was off-cuts from renovations and demolitions.

“The peaks didn’t always correspond with the coldest weather, suggesting some of the burning is opportunistic,” Dr Davy said.

“These studies show that air in New Zealand urban centres is not as clean as we would like to think.”

In fact some of the winter measurements were more like the air we expect to encounter in polluted overseas cities, he said.

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Several councils have embarked on enforcement and community education programmes, but there is clearly more work to do in this area

Dr Perry Davy

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The study found the highest average concentrations were in Nelson and Richmond along with Wainuiomata, Hastings, and Christchurch. Other urban centres from Whangarei to Invercargill also showed elevated levels during winter.

What is unknown is the exposure risk in and around the homes that are burning contaminated timber, where the concentrations could be many times higher and so pose a health risk for children exposed to these potent neurotoxins.

A further issue is the disposal of domestic fire ash that contains residual arsenic, copper and chromium. When ash is placed on gardens, it represents an additional exposure pathway through the consumption of vegetables grown in contaminated soils.

Councils are responsible for the management of air quality and most councils ban the burning of CCA-treated timber.

“Several councils have embarked on enforcement and community education programmes, but there is clearly more work to do in this area,” Dr Davy said.

GNS Science uses its capability in ion beam technology to analyse tiny particles on air filters that most councils collect at air quality monitoring sites around towns and cities. The analysis not only identifies dozens of different elements, but also their concentrations and that information can be used to identify the sources.

Councils use this information to help develop mitigation measures to improve the quality of air in urban centres.

See a video on testing air quality below.