The Department of Planning, Industry and Environment has introduced interim new hourly standards of 80.1 micrograms per cubic metre for coarse quality PM10 pollution, including dust from coal mines, and 62.1 micrograms for fine quality PM2.5 pollution, typically from coal-fired power stations and domestic wood-burning heaters.

While the new hourly guide to when air quality is poor or hazardous has been cautiously welcomed by Hunter epidemiologist and Doctors for the Environment spokesperson Dr Ben Ewald, he warned that "I've never seen the science" to back the hourly figures chosen by the NSW Government to indicate when air quality is poor.

"I'm not aware of any science that's been done to come up with those figures," Dr Ewald said.

Hunter community groups and long-time activists living near coal mine sites have slammed the move which sets an hourly "poor" coarse PM10 pollution figure of 80.1 while the 24-hour average PM10 exceedance figure remains at 50.

While the Upper Hunter Air Quality Monitoring Network has always provided hourly readings for 14 monitoring sites, the NSW Government has rejected residents' complaints about extremely high hourly readings near coal mines in the past in favour of the 24-hour average standards under the National Environment Protection Measure.

"They've introduced a new hourly rating but they've lifted the figure for when air quality is supposed to be poor," said Bulga resident Alan Leslie, who has battled the NSW Government for years over poor air quality near open cut mines, including when the monitoring network has shown hourly PM10 figures of more than 200.

"This has nothing to do with protecting us at all. It will just make them look better and provide another excuse for not doing anything," Mr Leslie said.

"Why have they gone to 80? Where has that figure come from? They've done it because of the bushfires and the smoke in Sydney but if you live near coal mines you're dealing with poor to hazardous air quality on a regular basis.

"And even when they say the air is hazardous near the mines, nothing happens."

Dr Ewald said the 80.1 hourly figure for poor PM10 air quality sounded reasonable, and provided some guide to people about when to restrict activities because of poor air quality. Before the department released its hourly standards last week Dr Ewald used a particle filter to cycle to work if the hourly PM10 figure was 100.

"In terms of alerting people it's useful because if you wait to see what the 24-hour figure is, and whether's been an exceedance, it's too late," he said.

But he was concerned by the 62.1 micrograms per cubic metre set as the standard for "poor" fine particle pollution.

"Where did they get that?" he said.

And neither figure was based on any science he had seen, although Dr Ewald believed there was a need for research to back hourly averages because of the health impacts of compromised air quality.

In 2018 Dr Ewald and Doctors for the Environment strongly criticised the Hunter's air quality monitoring regime as "trivial" and "ineffective".

"These are called national reporting standards but they're failing to protect people's health. There's no obligation for air to be better than these standards and the response is very vague. Apart from getting beaten up in the media there's not much likely to happen," Dr Ewald said after significant exceedances of the 24-hour PM10 and PM2.5 averages.

"In Muswellbrook there have been fine particle exceedances ever since the national reporting standards were established, and that's the more serious health problem because of impacts on human health, but again, nothing happens when there's exceedances."

On its website announcing the new hourly averages the department said it created a colour indicator scale based on the averages to "enable you to protect your health during poor air quality events".

"Air pollution has a significant impact on human health and the economy," the department said.

The new hourly averages for PM10 rate very poor at 120-160, and hazardous at greater than 160. Very poor PM2.5 is 93-124 and hazarous at greater than 124.

A Department of Planning Upper Hunter air quality quarterly report released on February 10 for winter 2019 showed daily average PM10 pollution exceeded the 24-hour national benchmark on 22 days between June 1 and August 31.

The report showed the significant increase in daily exceedances during winter over the past decade, with between zero and 10 days over the benchmark between 2012 and 2017, 29 days in 2018 and 22 in 2019.

The report raised the drought as a key factor in the increased exceedances, but residents including Muswellbrook Shire Councillor Graeme McNeill say pollution levels in other parts of the state affected by drought, but without open cut mines, have not been as extreme as the Hunter.

"You can taste the dust in the town sometimes," he said in 2018 after a "fiery meeting" between the council and NSW Government representatives over air quality, in which councillors called for mines to be shut down when air quality is hazardous.

A Department of Planning Upper Hunter Air Quality Monitoring Network report noted long term exposure to "fine particles from vehicles, industry, wood smoke and fires can cause and exacerbate heart and lung disease".

In 2019 the department issued $15,000 penalties to Hunter Valley Operations, Warkworth Mining and Wambo Coal for air quality violations.