High pollution days in Mosgiel last winter were at a similar level to previous years, but were still six days more than the national standard's aim.
An Otago Regional Council report on winter air pollution around Otago showed Mosgiel, an airshed 2 town, recorded seven high pollution days, up from five the previous year.
The council has monitored PM10 (very small particulates) levels continuously in Mosgiel since 2006.
High PM10 levels came from domestic solid-fuel burner, industry, and occasionally outdoor burn-off emissions.
National Environmental Standards set the air quality threshold at one breach of a concentration of 50 micrograms per cubic metre a year.
In June the town had already breached that level six times with another breach in July but during August and September it did not record a high level.
The highest reading recorded was at PM10 level of 108 micrograms per cubic metre followed by one of 72 micrograms per cubic metre.
Air quality scientist Deborah Mills said in her report outdoor burning may have contributed to the one reading of more than 100 micrograms per cubic metre.
The town's winter average was 28 micrograms per cubic metre compared with Dunedin's 18, Milton's 32, and the 46 of high-pollution towns Alexandra and Arrowtown.
Overall, Mosgiel was considered to have had 97 low pollution days and 19 medium pollution days on top of the seven high pollution days.
The national standard was for breaches to be reduced to one per year by 2020.
