Sydney has woken to a thick haze of smoke intense enough to trigger fire alarms across the city, as hazard reduction burns take place throughout the region.
Burns scheduled for last week were delayed by rain until the weekend, meaning Sydneysiders face a smoky start to the week.
The NSW Department of the Environment has issued warnings after the air quality degraded to "poor or worse" in the city's north-west, the central-east, and the south-west.
The scent of the smoke was prevalent overnight, particularly heavy around Olympic Park and the airport.
Asthmatic people are warned to keep their preventer close if they can smell the smoke this morning, and to keep doors and windows closed.
The smoke is expected to linger for several days.
The NSW Health Department warns that people with heart or lung diseases, older adults, children, and pregnant women may be particularly vulnerable.
People are advised to spend more time indoors or at air-conditioned venues, and avoid vigorous outdoor activity.
Air purifiers with a high efficiency particle air can be used indoors to help clear the air.
While surgical and cloth masks don't protect against smoke, P2/N95 face masks can – though they can also make it more difficult to breathe, the Department says.
A full list of smoke protection recommendations can be found online here.