AIR around Singleton failed national daily average health standards 10 times last Thursday and Friday.
Ten health alerts were issued late at night and two were early in the afternoon.
The first was at Mount Thorley at 10pm on Thursday and the second was an hour later at Camberwell.
The rest were at Singleton, Singleton north west, Maison Dieu, Mount Thorley and Camberwell at 1pm, 2pm and then 10pm and 11pm.
The warnings were the result of New South Wales environment department monitors detecting fine dust particles, known as PM10s, that can damage people’s respiratory tracts.