Sydney’s air quality will continue to be “poor” after a blanket of smoke covering the city prompted a spike in ambulance call-outs for respiratory issues on Tuesday.

Creating air-quality levels worse than parts of Beijing, the hovering smoke was caused by weekend hazard-reduction burns carried out around Sydney.

By late afternoon, more than 60 people with asthma or breathing difficulties had been treated by paramedics in Sydney, and more than 80 across the state.

Almost a third of the cases related to young children, NSW Ambulance said.

“Paediatric cases don’t normally make up one-third of our workload on a daily basis,” Inspector Giles Buchanan said.

“Our advice at this stage is if you can stay inside and out of the haze covering Sydney you are best to do so.”

NSW Fire & Rescue say the air is not expected to completely clear until Wednesday.

Parts of Sydney’s north west and south west recorded “hazardous” levels of air quality, as the city was given a “very poor” rating on Tuesday.

On a wider scale, the World Air Quality Index rated Sydney’s air quality as 164, while inner Beijing is listed as an “unhealthy” 152.

The elderly, the very young and those with respiratory conditions are being urged to take precautions as the air-quality impact is three or more times the national standard, NSW Health said.

“But also those without respiratory conditions should take precautions, (they) should stay inside, and avoiding vigorous exercise is really important on a day like today,” Dr Ben Scalley said.

“There are lots of large particles in the air but it is the ones you can’t see that have the worst impact.”

NSW Rural Fire Service spokesman Ben Shepherd said smaller burns are scheduled for later this week but these fires are not expected to affect the city’s air quality.

“They will be weather-dependent looking at the rain ahead but they are smaller burns, at around six hectares in size,” he told AAP.

-with AAP