Poor air quality can cause sore eyes and throats in people who are otherwise healthy. People with underlying conditions such as asthma, emphysema and heart conditions are at greater risk of more serious symptoms.

Smoke haze is forecast for parts of greater Sydney on Tuesday, with temperatures expected to reach 36 degrees in the city, 40 for Parramatta and Campbelltown and up to 42 in Penrith and Richmond.

Dr Broome said hot weather also strains the body, and can lead to dehydration, heat stress and heat stroke.

"Compounded by the continued impact of smoky air from bushfires, it’s important that people are prepared, particularly people with underlying medical and respiratory conditions," he said.

People should stay indoors during the hottest part of the day - from about 11am to 4pm, he said, and noted that keeping curtains closed and using a fan can help keep the heat out of homes. Dr Broome said it was also important to minimise physical activity and drink plenty of water.