Ambulance call-outs have climbed 30 per cent in NSW as people struggle for air in hazy bushfire smoke pollution, which has been likened to "breathing in soup".
A six-year-old boy was hospitalised after suffering a severe asthma attack at school in western Sydney on Friday while a 32-year-old woman was treated in southwest Sydney after having an asthma attack while shopping.
NSW Ambulance fielded some 2330 calls for help with asthma or breathing difficulties over the past week - 30 per cent more than an average week.
Over the same period, hospitals across the state have had a 25 per cent increase in emergency department presentations for respiratory issues.
NSW Health environmental health director Dr Richard Broome says the state is coping with the increased demand on health resources.
"This smoke is having an effect and it reinforces the need for those with heart and lung conditions to take these conditions seriously and to do what they can to avoid exposure," he told reporters on Friday.
"While we have seen an increase, it's manageable for us.
"Smoky conditions do have an impact on people's health, but the health system is well able to cope with the situations we are seeing at the moment."
Dr Broome said people with asthma, emphysema and angina should avoid outside activity.
NSW Ambulance spokesman Brent Armitage says people should take the smoky conditions seriously.
"NSW Ambulance would urge the residents of NSW to not underestimate these conditions - they can be life-threatening," he told reporters on Friday.
Student Sophie Gibbons, who lives in Sydney's north, says the lingering smoke over the past few weeks has made it nearly impossible for asthmatics to go about their daily lives.
"It's like I'm breathing in soup, or breathing through a straw," the 20-year-old told AAP on Friday.
"Walking anywhere outside makes me feel breathless, even if it's just a few metres to the letterbox."
Ms Gibbons said she could not remember a time she's had to use her inhaler so often.
"My nan is very worried about me. She keeps sending me messages saying 'Stay indoors today'. But the smoke is just everywhere. It's even getting inside our house."
One of the main concerns with the smoke is minuscule PM2.5 particles, which are so tiny they pass through most masks.
"A P2 mask does filter out these particles but is only effective if there is a good fit and an air-tight seal around the mouth and nose," Dr Broome said.
"Evidence shows that this is difficult to achieve in practice so they may not provide the benefits people are hoping for."
Vets have also urged owners' to keep their pets inside to avoid the smoke.
Air quality ranged from "very poor" to "hazardous" across large parts of eastern and southwest Sydney on Friday.
The NSW environment department said this season's bushfire emergency has caused "some of the highest air pollution ever seen in NSW".
Australian Associated Press