A dust haze settled over the Illawarra on Wednesday morning after strong winds carried dirt from parched parts of inland NSW to the coast on Tuesday.
Weatherzone warned the air quality may deteriorate in some areas before it improves when a change moves through later on Wednesday.
The Illawarra region recorded an air quality index value of 207. A good value is considered between 34 and 66.
An air quality warning was issued for the region with the Office of Environment and Heritage advising people with heart or lung disease to avoid outdoor exertion and to stay indoors, if possible.