Christchurch has exceeded World Health Organisation pollution levels six times this winter and Environment Canterbury is trying to work out why.

E Can air quality science team leader Tim Mallett says of the six breaches, only three are ‘typical’ winter breaches (i.e. occurring after a cold, still night).

He says the other three days saw high PM10 recorded at the Woolston monitoring station, but not at St Albans, and were mainly coarse particles, not fine, so are unusual.

Mr Mallett says the coarse particles appeared overnight on Monday 16 June and Tuesday 17 June with very little wind and it was warm, so it was extremely unusual.

He says at this stage, we don’t know where the coarse particles are coming from.

“Our instruments appear to be working correctly, but we are checking them to be absolutely sure it’s not instrument error.”

“There were a lot of coarse particles at Woolston in the months after the earthquake, but these had dropped off in recent years, back to normal.”

Environment Canterbury air quality director Tafflyn Bradford-James says Environment Canterbury has not issued fines related to smoky chimneys or use of non-compliant wood burners this season.

He says Ecan’s approach in this area has always been education first – teaching people how to burn smoke-free, and ensuring they are aware of what financial assistance is available to upgrade from a non-compliant wood burner.

“We do have the option to issue an abatement notice and/or infringement in certain circumstances, and this is something that we may need to consider in cases where we have exhausted other avenues.”