Just weeks into winter, Napier and Hastings have exceeded air quality standards set to reduce air pollution.
Recorded over a 24-hour period last weekend in Marewa, Napier and St Johns, Hastings, the average level was five micrograms PM10 (very small particles) per cubic metre of air above the acceptable level.
Hawke's Bay Regional Council air quality scientist Dr Kathleen Kozyniak said the small particles in the air posed a risk to the public.
"The smaller the particles are, the further they get into your system. The really small stuff can get into your bloodstream.
"They have been associated with respiratory problems, linked with lung cancer. There's even things like low birth rates and tenuous links with things like Alzheimer's so there's quite a range."
A combination of no wind and cold temperatures led to higher smoke levels in the air.
"We've been reasonably lucky in the past few winters where the weather systems have been quite rapid-moving and we haven't had a big high sit over us for days and days, but in this case we were unlucky."
Kozyniak said particle concentration had been higher in the past but the main obstacle was what people burned.
"It's just eliminating the gross emissions from old inefficient burners and anyone that's not burning dry wood.
"If you're burning wet wood you're putting money down the drain really."
This was Napier's first exceedance in four years and the eighth for Hastings in the past three years.
Council "Heat Smart" programme manager Mark Heaney said he was disappointed by the levels.
"This is particularly disappointing in terms of the result for Napier where we thought we were on track to reach clear air every winter."
The Heat Smart programme gives grants and loans to those wanting to upgrade old fires and educates the public on how to reduce emissions.
Heaney said smokey domestic fires contribute to about 87 per cent of the problem, and they had replaced 12,500 so far.
He said people with non-compliant fires would be contacted by council representatives and given notice to disuse or remove it. If the notice was ignored, a $300 fine could be incurred.
Heaney said wood needed to be kept undercover, seasoned and be standing for 6-12 months to dry out properly.
"Unfortunately you get a lot of people chopping wood down, sticking it in bins at the end of the drive and selling it cheap and it really is a false economy."
He said more air quality exceedances would be likely.
"I'm expecting more exceedances because we are still solving the problem, we haven't solved it yet."
Breathe Hawke's Bay clinical nurse manager Julie Shaw suggested that about 25,000 people in Hawke's Bay had a respiratory illness and air pollution was a trigger.
"Air pollution is recognised as a trigger of asthma and any respiratory disease. It is a trigger of people becoming more symptomatic and requiring more of their relieving medication."
Shaw said most people with respiratory issues would experience shortness of breath, coughing, wheezing and chest tightness when they encountered polluted air.
She said many people identified winter as the worst time and that some people don't go out at night because of the pollution.