The Maison Dieu PM10 monitor tipped into the poor range at 10pm on Wednesday night and remained at that level until 12am Thursday.

The Office of Environment and Heritage (OEH) online air quality index values showed that throughout most of Wednesday afternoon the monitor was reading the air quality at Maison Dieu as fair, the third lowest range.

The Maison Dieu monitor registered the poorest air quality out of all the 25 monitors that are online on the OEH air quality index for the day.

A poor range recommends people with heart or lung disease limit outdoor exercise.

A spokesperson at the OEH said the exceedances was due to the very windy conditions experienced in the region from the west-north-west.

The Bureau of Meteorology had a wind speed of 19km/h at 3pm on Wednesday from the north-north-west, the strongest received in the week.

The OEH said they were not aware of any blasting exceedances in the area on that day that could have contributed to the exceedances.

However dust from mine overburden is one of the air quality issues identified as being earmarked for improvement as part of the NSW Coal Mining Benchmarking Study: International Best Practice Measures to. Prevent and/or Minimise Emissions of Particulate Matter from Coal Mining.