The Government is to review air standards to see if they are realistic.
But Green Party co-leader Russel Norman says that means it intends to weaken or delay them.
Environment Minister Nick Smith today said air quality standards needed to be "practical and achievable" and 10 cities and towns, including Auckland and Christchurch, were unlikely to meet the standards set in 2005 by the 2013 deadline.
A technical advisory group would review the national environmental standards for particulate air pollution under the Resource Management Act.
The review delivered on a pre-election commitment and on concerns raised at the Jobs Summit, Dr Smith said.
"We are at the halfway mark between when the standards were set in 2005 and when they must be complied with by 2013 so it makes good sense to review progress," he said in a statement.
"Air quality is critical to New Zealanders' health and our clean green reputation. We are committed to ongoing improvements but want to ensure we have the policy and timetable right."
Industry and employment could be damaged if consents were not renewed or issued because of failure to meet standards, Dr Smith said.
"The review needs to look at whether it is fair to solely punish industry for non-compliance when the overwhelming pollution is caused by home fires and, to a lesser degree, vehicles. It will also look at the costs and benefits of the air standard and the optimal timetable for achieving improvements."
The review also needed to take into account the Government's plan to subsidy home insulation and clean heating, he said.
But Dr Norman cast doubt on the Government's motives.
"It sounds like they are planning to weaken them or delay them," he told NZPA.
"You've got regional councils who just haven't got it together because this isn't new, it's no surprise, and they just didn't get it together to start to phase out polluting home heating, and traffic is the other issue."
Dr Norman said central government did have a role to play.
"The scheme will help... the problem is if every time they don't meet the standards they are just changed they lose their credibility.
"Why would anyone in the future take any notice of these standards if you can wait until National gets in government and they will weaken them."
An Environment Ministry report had found poor air quality cost the country $1 billion a year and contributed to the deaths of 1000 people annually.
"It has a significant impact on people's lives and also on the economy," said Dr Norman.
