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A new study has attempted to calculate the health costs caused by dust from unsealed roads and has found sealing populated roads could be cheaper in the long run if health benefits are taken into account.
The NZTA-funded study monitored a road in the Far North for two months, recording dust levels from sealed, unsealed and chemically treated sections of road.
It found the level of dust particles from the unsealed road exceeded the National Environmental Standards for Air Quality for 30 per cent of the trial.
The study, produced by Golder Associates, focused on the tiny dust particles, called PM10 particles, which are known to cause respiratory and cardiovascular morbidity, including lung cancer.
Using a computer model developed to assess the health impact of PM10 particles in NZ, the research found that dust from the road was costing residents about $21 a year in health-related costs when compared with residents on the sealed section of road. About 91 per cent of that cost was due to reduced life expectancy.
By contrast, over a 40-year period the cost of sealing and maintaining the road would only be $15.40 per person a year, meaning sealing the road would save money long-term.
The study also looked at the effect of using chemical dust suppressants, but found the costs outweighed the benefits, resulting in $12 in annual health benefits per person, but $15 in extra costs.
The road had about 260 vehicles a day, including about 80 trucks, but heavy traffic had a voluntary speed limit of 20kph in an effort to reduce dust. There were eight houses and about 23 residents on the 1km road.
An NZTA spokesperson said it was important to note that the costs and benefits of sealing a road would vary depending on traffic levels, the number of residents, weather, geology and topography of the site and the results are specific to the Far North road.
There were also cheaper methods to reduce dust which were not looked at in the study, including other dust suppressants, shelter belts and other sealing techniques.
But the report authors noted that if the broader costs of unsealed roads were taken into account, like increased accident rates and vehicle costs, then the benefits of road sealing would be significantly higher.
It also noted that areas with unsealed roads were becoming more populated due to the growth in lifestyle blocks, and new houses tended to be built closer to unsealed road.
The report had presented to the Waitemata District Health Board, the Auditor General and Local Government New Zealand.
The findings build on a 2013 Northland Regional Council study on the impact of dust from unsealed roads, which found levels exceeded National Environmental Standard for prolonged periods.
Funding changes mooted
NZTA is developing a new approach to funding road sealing based on the findings, which could result in a boost in sealing budgets around the country.
Roading authorities, like Auckland Transport, set the level of funding for road sealing, but NZTA decides whether to subsidise the work.
In practise, virtually no road sealing is funded by NZTA, as it says it does not reach a benefit-cost ratio needed for the work to be economic.
NZTA Northland and Auckland regional director Ernst Zollner says it is reviewing the formula used to calculate the cost-benefit of road sealing.
“Using the report, we have developed an approach on how councils can apply for financial assistance for dust mitigation,” Mr Zollner says.
Auckland Transport has said it is considering the report, but would not comment further on whether it was reviewing its road sealing policy.
A council responsibility
Councils could be held responsible for the dust from unsealed roads under the Resource Management Act (RMA) and the Health Act, according to the report.
“As the developer and operator of the roading networks within their respective districts, the relevant territorial local authority [council] has responsibility for managing the dust discharged from public unsealed roads,” the report said
Councils may have to consider investing in dust mitigation due to their responsibilities under the RMA and National Environmental Standards, it said.
$10 million campaign
Rodney Ward Councillor Greg Sayers has called for the road sealing budget to triple to $10 million a year for the next 10 years.
“Not all the roads need dust control, however, with massive housing intensification those roads that are now creating a dust nuisance for people living on them are a priority,” he said.
Council spends $3.3 million a year on road sealing, which sealed about six kilometres, while Rodney had 673km of unsealed roads.
