The report, due to be published next month, concludes that there is little evidence that air quality is improving - despite government reassurances that the atmosphere is gradually getting cleaner.
The news could not have come at a worse time for ministers - who set out the Government's vision for "a truly integrated transport revolution" yesterday.
Since being elected, ministers have ceaselessly repeated that they intend to get "people to use their cars less" in order to reduce pollution levels.
According to today's Economist, the new report will say that at street level some pollutants, such as nitrogen oxide, are increasing despite claims by the Department of Environment, Transport and the Regions that national standards are improving.
The commission, made up of highly-respected scientists, will also question whether ministers can meet their target of a 20 per cent reduction in carbon dioxide levels without tougher measures to restrain traffic.
Yesterday's launch of the consultation paper on transport by ministers will help to assuage these doubts.
John Prescott, the Deputy Prime Minister and Secretary of State for Transport, Environment and the Regions, made it clear that traffic levels could not grow at present rates.
"We would need a 100-lane motorway from London to Leeds to cope with the extra 10m cars - so something has to be done," he said.
The Government should take some solace from the fact that the new report is a reaction to the previous administration's inaction.
Three years ago the Royal Commission called for a doubling of petrol prices by 2005, justifying the draconian measure by claiming that car fumes caused up to 10,000 deaths a year.
A price rise may not be enough. A recent report by the Automobile Association found that 82 per cent of motorists would still use their cars even if petrol prices doubled over 10 years.
However, more worrying for transport planners is that the annual petrol price hike has been undermined by falling world oil prices.
But the commission's 100-plus proposals where largely ignored by John Major's Cabinet - a snub which has left the present Labour administration with the report's damning conclusion that too little has been done too late.
Experts are still generating new ideas to tackle traffic growth. Tom Burke, formerly special adviser at the Department of the Environment, outlined a road "permit" scheme in today's New Statesman magazine.
Mr Burke calls for "unrestricted access" for public transport on the road network - but would restrict petrol sales to motorists who possess a road permit.
A number of these could be auctioned to the highest bidder by the Government while motorists would receive a "free" set for a given time period.
"The big resistance would come from the psychological shock of confronting people directly with the notion that road space ... is scarce and bears a cost," writes Mr Burke.
While ministers ponder their next move, pollution levels are bound to rise.
The families of seven asthmatic children took legal action last year in an attempt to force Greenwich Council in south-east London to close Trafalgar Road - a main thoroughfare - when traffic fume levels peaked. But the council objected and the families' application was denied.
However, under plans announced by Michael Meacher, the Minister for the Environment, targets would have to be met under a "National Air Quality Strategy" - even if roads had to be shut down in order to reduce the pollution levels.
Mr Meacher said at the press conference that the necessary legislation would be in place before the "end of the year".Reuse content