Chimney filters are being trialled in Reefton to help curb air pollution in the West Coast town.

In May, the West Coast Regional Council (WCRC) installed trial tubes on a property where coal only was burnt, and another where a mixture of coal and wood was used.

Council staff have been monitoring the devices fortnightly over winter to assess the build-up of soot inside the chimney.

The filters, manufactured in Switzerland, use electrostatic principles to reduce particulates being emitted from home burners. An electronic charge pulls the particulates to the chimney wall, where they accumulate and can be cleaned out with a chimney sweep.

Reefton is the only West Coast town where air-quality monitoring is undertaken.

The WCRC received a submission on its annual plan from Westport resident Martin Dobson, who requested air-quality monitoring be undertaken in his town, but the suggestion was not adopted.

After limited monitoring in 2001 to 2003, the Ministry for the Environment recommended the WCRC focus on Reefton as a priority. With low wind speeds over it, the town often experiences a temperature inversion where cold and polluted air gets trapped close to the ground. The same conditions exacerbate air pollution in Christchurch and Timaru.

The ministry's national air-quality standards set an exceedance where PM10 (particulates smaller than 10 microns in diameter) levels surpass 50 micrograms per cubic metre of air, averaged over 24 hours.

Under the standards, Reefton, Christchurch and Timaru are expected to have no more than three exceedances a year by September 2016, and no more than one per year by September 2020.

Reefton has exceeded the standards 12 times this year already.Christchurch has also 12 times and Timaru, 27 times.

WCRC planning and environment manager Michael Meehan last week told the council the trial filters were working as expected. A public meeting would be held to discuss the trial with residents.

In 2012, the possibility of a coal ban in Reefton was floated by the council to rein in air pollution.