Independent analysis of the air inside Sydney's M5 East tunnel has revealed frightening pollution, including toxic gases and lung-damaging dust.
The study commissioned exclusively by 7News says drivers are at risk from asthma and heart disease.
The findings have alarmed key health groups and local residents like Jenny Lukinic.
Jenny lives about half a kilometer from the M5 exhaust stack, and she says it's too close for comfort. She wants to move, for her son's sake.
"They have got developing lungs and obviously I'm concerned about it," Ms Lukinic says.
The stack pumps out fumes from the four kilometre M5 East Tunnel and more than 130,000 drivers use it daily, unaware of what they're being exposed to.
"There aren't even warnings at the M5 that this health risk exists," Jones says.
Roads and Maritime Services publishes air quality results for outside the tunnel every hour, but results from inside are secret.
To measure the pollution inside 7News engaged expert scientists who drove through the tunnel, checking for a range of pollutants and particles, and the results were alarming.
Adam Garnys from scientific services company Cetec says that a child would be better off travelling inside the car with a driver smoking nicotine, than travelling through the M5 with the windows down.
The difference is that smoking comes with warnings, the tunnel doesn't.
Cetec found all results for nitrogen dioxide, carbon monoxide and particulate matter were significantly elevated.
Just one peak-hour trip would expose a driver to double the safe limit for nitrogen dioxide noting such exposure has been associated with increased mortality. While particulate matter, or dust, was up to 10 times the safe limit.
The report also noted that the airborne respirable dust in the M5 is highly likely to contain toxic substances.
Cetec's Adam Garnys says it could cause an asthma attack, inflammation of the respiratory system, or exacerbate other ongoing medical effects if you were to do that drive on a daily basis.
Leading health experts believe this research proves the government needs to clear the air, and start testing for the most dangerous pollutants and release those results.
They say it will give drivers the information they deserve about the pollution.
Tony Thirlwell from the Heart Foundation says that the more information the consumer has the better.
"We want informed consumers to make informed decisions about their health," Thirlwell says.