Dusty roads - the problem
Traffic on unsealed roads causes dust. It’s a problem for the people who live close by and a problem for the environment. The dust caused by traffic can;
- land on roofs and contaminate drinking water
- cover gardens and household property
- add sediment into stormwater
- cause health problems for people with breathing disorders
- make it harder for drivers to see
Because of this we support the use of suppressants to take the edge off the effect on the environment and the neighbours.
Stopping the dust
There are lots of products available to suppress dust on roads. When you choose a product you need to think about the geography and weather of the area and the effects the suppressant could have on the environment.
It used to be that waste oil was used as a dust suppressant. Now it is illegal to apply petroleum based oil to roads. We now know the oil is harmful to the environment and the Regional Water and Soil Plan for Northland bans the use of waste oil for dust suppression.
What's wrong with used oil?
Even clean off-the-shelf engine oil contains additives (such as zinc compounds). During its use in engines, it becomes contaminated with the by-products of combustion and metals from engine wear and tear.
These contaminants can include cancer-causing polycyclic aromatic hydrocarbons (PAHs) and metals such as aluminium, cadmium, chromium, lead and copper.
When used oil is applied to roads, these contaminants bind to dust particles, and can then be washed off roads by rainfall or blown into the air. Some of the used oil may also simply evaporate into the air.
Humans may swallow these harmful materials through drinking contaminated water or breathing in contaminated air or dust.
A nation-wide Ministry for the Environment study in 1997 concluded that the environmental and health risks of applying used oil to roads as a dust suppressant are too great, and that the practice should be strongly discouraged.
Sealing or paving
The most effective method of dust suppression is sealing the road. It costs about $150,000 per kilometre. Most District Councils have annual programmes that extend the length of sealed road in a district. Roads are prioritised for sealing based on, among other things, how many vehicles use the road.
Water is the cheapest form of dust suppression and is best suited for reducing dust in the short-term. How long it is effective depends on the amount of traffic and weather. It can vary between 30 minutes to 12 hours. Regular light watering is more effective than less frequent heavy watering.
There are a large number of dust suppressants available in the market. It is not the role of Northland Regional Council to hold a database of these products however the Proposed Regional Plan allows the discharge of a dust suppressant onto roads as a permitted activity, provided the dust suppressant is approved for its intended use by the Environmental Protection Authority (EPA) or has been determined by the EPA not to be a hazardous substance.
Contact your district council or local roading contractor for more information on the different dust suppressants available in the market.