Millions of people are being poisoned by air pollution up to seven times higher than public safety limits at Waverley station in Edinburgh, a study for Network Rail has revealed.

Exhaust fumes from trains and taxis, coupled with toxic dust kicked up by construction works, are endangering the health of commuters, tourists and workers – particularly those with asthma, lung or heart conditions, experts say.

Politicians have reacted with shock and horror to the revelations, and are demanding urgent action to protect the 25 million people who use the station annually. Network Rail, the company that runs Waverley, says it is doing what it can to cut the pollution.

Waverley, situated in a low, glass-roofed hollow in the centre of the capital, is one of the busiest stations in the UK outside London. It seems it may also be one of the most polluted.

It is the only British mainline railway station that still allows vehicles, including taxis, private cars and delivery trucks, to drive right inside it. It is also three-quarters of the way through a four-year, £100 million revamp, which means almost constant cutting, drilling and pounding, confining passengers under scaffolding and awnings.

To help assess the risks of air pollution, Network Rail commissioned consultants to monitor the station continually for three weeks in October and November. Their report was released to the Sunday Herald last week, after repeated requests.

Scientists measured levels of nitrogen dioxide, a gas emitted by vehicle exhausts that damages the lungs, blood and immune system, at four locations around the concourse. They found average levels varying from 205 to 304 micrograms per cubic metre, compared with the annual average "air quality standard" of 40 required by European law.

According to experts, the levels to which many passengers were exposed at peak times would be much higher than another legal limit of 200 micrograms per cubic metre, set for one hour's exposure. The concentrations of nitrogen dioxide in the station were four to six times higher than in the surrounding streets.

Scientists also found high levels of tiny particles known as PM10s, which inflame lung tissue and increase the risk of heart attacks and strokes. They were nearly twice as high as the air quality standard, and up to 10 times higher than in nearby streets.

Highly toxic diesel pollutants known as polycyclic aromatic hydrocarbons, or PAHs, were four times higher than the relevant air quality standard, according to the report. They are blamed for causing cancers.

"The levels of air pollution at Waverley station are significantly higher than in the surrounding streets, and may breach internationally agreed air quality standards," said Dr Sean Semple, an air pollution expert from the University of Aberdeen.