Evidence increasing over ultra-fine particulate matter being a threat to health

The tiny material comes from car exhausts, home heating and forest fires. Photo / Warren Buckland

Evidence is increasing that ultra-fine particulate matter — that smaller than 0.1 micrometres — is a threat to good health.

The tiny material comes from car exhausts, home heating and forest fires.

It gets deposited in people's lungs, and the small size means they enter the bloodstream and move around the body causing cellular and genetic damage.

Little is known because long-term studies on health effects are not yet available.

Ammonia, from intense farming, is another threat identified in the report.

International research shows that excess nitrogen as ammonia can acidify soil and cause changes in biodiversity by creating nutrient imbalances that favour one species over another, often favouring exotic species over natives.

Because soils in New Zealand tend to be naturally low in nitrogen, even small increases have the potential to harm biodiversity and ecosystems.

Yet another potential issue was sulphur dioxide emissions from a growing number of ships visiting the country.

Studies in Auckland had found that sulphur dioxide concentrations were higher near the waterfront and are highest when the wind comes from the direction of the port.

Tracer studies that could "fingerprint" emissions from shipping by measuring nickel and vanadium, which were predominantly associated with shipping emissions, found the highest levels near the water.