A former helicopter paramedic and pilot fears lives will be at risk if a new rescue chopper is based in fog-prone Lismore on the New South Wales north coast.

Key points: NSW northern regions rescue helicopter base to move to a new site in Lismore

NSW northern regions rescue helicopter base to move to a new site in Lismore Fog regularly grounds aircraft at Lismore

Fog regularly grounds aircraft at Lismore Chopper crew list incidents where fog has already stopped rescue missions

The new multi-million-dollar operation is part of the NSW Government's plan to improve helicopter rescue across the state.

Frontline staff have been pushing to have the base built at Ballina on the coast rather than Lismore, which has a much higher incidence of heavy fog which prevents rescue missions from taking off.

Retired paramedic, Kim Hanlon, fears lives will be place in jeopardy if the rescue helicopter is regularly grounded by fog. ( Supplied )

"Lives can be in jeopardy, yes, because you (would) now have a $20 million machine with a doctor and a paramedic and it's grounded," said Kim Hanlon, an intensive care paramedic who retired in 2014 after a decade with the northern NSW Life Saver Rescue Helicopter service.

In an exclusive interview with 7.30, Mr Hanlon said he was speaking out because his colleagues within the service would risk their jobs if they did so.

"Concerns have been raised to me over quite some time by paramedics who work at Lismore helicopter base about how often they cannot take off or land due to fog," Ballina Greens MP Tamara Smith told 7.30.

"They've estimated to me that between 2015 and 2016 there were 30 times that they could not take off or attend a rescue because of fog."

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"Close to a million residents are supported by that service and then we've got 1.2 million tourists that come through the Byron-Ballina gateway, so this is hugely important."

Dr Ron Manning, the director of Aeromedical Services with NSW Ambulance, said the rescue service has worked successfully out of Lismore for the past three decades and he was confident it remained the right location.

"Construction of the new base (at Lismore Airport) will begin within several weeks," he said.

Fog prevented seven helicopter rescue missions in February and March: staff

Having rapid access to specialised care in the first "golden hour" after a medical emergency can be the difference between life and death and improved health outcomes.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 6 minutes 35 seconds 6 m Rescue Helicopter workers concerned new helipad site too risky

According to frontline staff in Lismore, there were seven cases in February and March this year, where fog grounded rescue teams.

In one of the cases, a 27-year-old Irish national was critically injured in a head-on collision south of Grafton in the early hours of March 3.

Due to fog it was seven hours before the patient was airlifted to a major trauma hospital

Four days later, at around 7:00am, a young child was denied the helicopter service, again due to fog.

The child had fallen two storeys from a window at the coastal village of Ocean Shores.

Not all missions grounded by fog are officially logged: pilot

Dr Manning says Ambulance NSW records show that the fog affects a night mission only once every three to four months.

"I've been in this job for a while now and I cannot recall any mission where there's been an adverse patient outcome that you can directly relate to an inability to respond due to weather over those 30 years," he said.

But a former pilot with the service told 7.30 that missions refused because of fog were not always recorded because they had not been officially "tasked".

"There could be another three jobs that come (in on a foggy night) but they won't call us because they know we are fogged in," said Marty Hanna, who now flies helicopters with Emergency Management Queensland.

"So can be quite deceiving going off those figures."

Fog at Lismore Airport

Independent analysis of Bureau of Meteorology weather data commissioned by the ABC shows that fog is a greater problem in Lismore than Ballina.

"The number of hours per month that cloud is lower than 800 metres ... is about four times more in Lismore than Ballina," said Michael Reeder, Professor in Earth Sciences and Atmospherics at Monash University.

The rescue helicopter cannot take off if visibility is below 800 metres.

An independent review by Avipro for NSW Ambulance Service found that fog between midnight and 8 am was an issue on one third of the nights between May and September 2015.

But it concluded that Lismore Airport was still a suitable location for the new rescue helicopter base.

7.30 has confirmed that a site at the Ballina airport was offered to the rescue helicopter at the time when a decision on a new site was being made.

Rescue Service General Manager denies politics at play

Northern Region Rescue Helicopter Service General Manager, Kris Beavis, denies politics played a role in selecting the new site ( Dominique Schwartz )

The general manager of the Northern Region Rescue Helicopter Service, Kris Beavis, stepped down from his helicopter role last year to run as the National Party candidate for the state seat of Ballina.

He was defeated by the Greens' Tamara Smith, with the National Party losing the seat for the first time in 27 years.

In late April 2016, at a meeting at the rescue helicopter base, Ms Smith said she was told by Mr Beavis "if the base moves, I will lose my big donors."

7.30 asked Mr Beavis if he was concerned that moving the rescue service from its home of three decades would see a drop in community funding.

"Hopefully we're never put in that situation, whether it's by relocation or by another event which puts us in a situation where our funding did go on the trajectory you're (suggesting)," he replied.

Critics say the site for the new Lismore rescue helicopter base will be affected by fog ( Dominique Schwartz )

Tamara Smith has called on the New South Wales Health Minister Jillian Skinner to put construction of the new base on hold while investigating other locations including Ballina airport.

"Who will take responsibility in the unfortunate event that a loss of life can be directly attributed to the decision to place the Westpac Rescue Helicopter base in a location that local staff say is prone to fog?" she asked.

For the Ballina MP this is personal.

Twenty-two years ago her baby's life was saved by the rescue helicopter.

"It was the difference between life and death, it was that simple, the thought of a baby or anyone not being airlifted because of fog is unthinkable," Ms Smith said.