Air pollution in Hastings has exceeded the national standard for the third time this year.
In Thursday night's frosty weather many householders used their woodburners to keep warm.
Checks on Friday of the Hawke's Bay Regional Council's air quality monitoring equipment showed that the concentration of small particles - known as PM10 - was 86 micrograms per cubic metre.
The national standard is no more than 50 micrograms.
The air in Napier exceeded the standard for the first time, with a concentration of 61 micrograms.
Last week the Environment Minister changed the compliance date for three exceedings a year from 2013 to 2018.