Airborne particulate matter accounts for about 1,200 New Zealand lives annually through respiratory illness, over three times the 2023 national road toll.

A significant proportion of that particulate matter originates from dirty fuel like coal or the burning of wet firewood.

When any fuel is burnt in domestic home fireboxes, the particulates travel up the flue and into the atmosphere. When inhaled, small particulates embed in the lungs instigating or aggravating respiratory ailments already present.

The issue is aggravated dramatically when an immersion layer traps the particulates, not allowing them to disperse in the wind as they would normally.

Unfortunately, the geography surrounding Central Otago’s main population centres provides a perfect catalyst for the formation of immersion layers that can often last for days before dispersing. 

Up to 95 per cent of air emissions in Alexandra, Clyde, and Cromwell come from chimney emissions, mainly from burning coal or wet wood.

To help limit the dangerous particles heating units throw into the atmosphere, Otago Regional Council (OCR) provides advice online; here is a sample:

• Only burn dry wood (with moisture less than 20 per cent). You can check the moisture level of wood with a wood moisture reader (available at most home hardware stores).

• Don’t burn rubbish, plastic, green waste or electronics.

• Use kindling and plenty of paper to start your fire quickly – remember, a hot fire is an efficient fire.

• Don’t burn coal – it produces more harmful pollutants than wood and may damage your burner.

ORC has upgraded monitoring sites in Central Otago. It can now record finer particulate matter concentrations in the air as small as Particulate Matter 10 (PM10).

An air quality monitoring site in Clyde. PHOTO: Supplied/ORC

PM10 are solid or liquid particles in the air, smaller than 10 micrometres, and include vehicle and industry emissions and natural sources such as dust and pollen. 

The primary source of PM10 in Central Otago is home heating emissions.

The ORC provides comprehensive advice and information on air quality for homeowners here. https://www.orc.govt.nz/managing-our-environment/air