New South Wales's top fire brass has weighed in on a national debate about hazard-reduction burns, saying the practice made his organisation "public enemy number one" last year.

Key points: Some people claim more hazard-reduction burns should have been done in NSW

Some people claim more hazard-reduction burns should have been done in NSW But RFS Commissioner Shane Fitzsimmons says that's not true

But RFS Commissioner Shane Fitzsimmons says that's not true He also pointed out his organisation had been criticised for doing too many burns

Hazard reduction burns have come under the microscope in NSW, as Australia suffers through its worst bushfire season in living memory, with some arguing more should have been done.

A total of 1,687 homes in NSW have been destroyed this fire season, and 20 people have died.

NSW Rural Fire Service (RFS) Commissioner Shane Fitzsimmons insists hazard reduction is an important element of fire prevention, but it's not a panacea.

"Let's not forget, only a matter of months ago in New South Wales, we and the land management agencies, particularly national parks and forestry, we were public enemy number one because a byproduct of hazard reduction burning is smoke and yes, there's a very significant health issue with smoke," he said.

Health warnings due to poor air quality have been a regular occurrence in Sydney, and other densely populated parts of the state in recent months.

Hazardous air quality ratings have been common and, on some days, Sydney has been classified as the most polluted city in the world.

Federal Nationals MP Barnaby Joyce in November called for more hazard-reduction burns during winter in a bid to reduce bushfire fuel.

He attacked the Greens, claiming they did not support the practice — something the party's politicians deny.

The Commissioner has also defended fire management agencies saying claims by some politicians that "Greenies" have disrupted prescribed burning were not true.

"We are not environmental bastards, we actually work through a sensible, environmental regime," he said.

"Our priorities are life, property and that environment ranks third."

Many Sydneysiders have had to make lifestyle changes due to smoke in recent months. ( AAP: Steven Saphore )

He said hazard reduction burns were being disrupted by changing weather conditions and longer fire seasons.

He also said the burns did nothing to combat the massive "mega-fires" burning in NSW.

"Hazard reduction burns that are only two years old, we're seeing these fires on these bad days just skip straight through it," he said.

"We're only seeing effective amelioration on fire spread through hazard reduction areas that have been done so in the last 12 months."

Hazard reduction burns are becoming more difficult due to prolonged fire seasons. ( Supplied: NSW RFS )

NSW Premier Gladys Berejiklian dismissed suggestions NSW had not conducted enough hazard reduction burns.

"Our focus at the moment in NSW is on the recovery effort," the Premier told ABC Radio Sydney.

"I think everybody that has their own agenda to push should actually think about the people who we have to support at this time."

Ms Berejiklian promised her Government would review the state's fire management strategies once the immediate crisis was over.