Warning on hazardous air quality
NSW Health said many areas in the state were experiencing poor to very poor air quality, even hundreds of kilometres away from the fires.
The Australian Medical Association's NSW president, Dr Brian Owler, said heavy exercise should be avoided.
"The last thing you want to do is to go out for a jog when you're breathing in such heavy pollution," he told AAP.
Asthmatics should also ensure they have their puffers with them at all times, he added.
Professor Wayne Smith from NSW Health urged asthma sufferers to follow their asthma action plan.
"Fine particles can irritate the lungs of healthy adults, so it is best to avoid any prolonged outdoor exercise," he said in a statement.
An Ambulance NSW spokesman said there had been a marked increase in the number of call-outs to people with respiratory problems since the fires broke out last week.
"We expect to continue to see an increase," he said.