Residents of Sydney woke up shrouded in smoke on Tuesday, as scores of bushfires rage across the region.
Strong winds overnight brought smoke from fires inland, pushing the air quality in Australia’s largest city to beyond “hazardous” levels at times.
About five million people live in the city, which has been affected for weeks by fires.
Six people died in bushfires in New South Wales since October.
Temperatures soared to 37C (98.6F) in the city’s west. Parts of the city recorded air pollution levels at eight times higher than the national benchmark.
Health officials asked people to stay indoors and avoid physical activity. They also shared first aid guides on how to help asthma sufferers and others with respiratory problems.
“The smoke is likely to hang around for the next few days,” warned the New South Wales Rural Fire Service.
Close to a 100 bushfires continue to burn. Authorities said some 460 homes were destroyed since blazes flared up on 8 November.
Officials have warned that blazes could escalate later this week when heatwave conditions reach New South Wales and neighbouring Queensland, where scores of fires are burning.
Meanwhile, a “catastrophic” fire danger warning has been issued for parts of South Australia. The state capital, Adelaide, is forecast to reach 42C on Wednesday.