Cases of 'Tube rage' may rise on London Underground (LU) unless air quality improves, a report says.
The report says people may stop using the Tube
Experts say a drop in oxygen levels combined with overcrowding can lead to feelings of anxiety and aggression.
Entitled 'A Breath of Fresh Air Underground', the report by transport specialists Fereday Pollard, calls for immediate improvements to ventilation.
But LU has dismissed the report saying it was based on "old research and supposition".
Metronet, which looks after maintenance on parts of the network, has commissioned an engineering consultancy to oversee refurbishment of 150 stations in the next eight years.
But the report said upgrades did not include plans for improvement to ventilation and comfort below ground.
Ben Fereday, of Fereday Pollard, said: "Not building for better ventilation now is a mistake as clean air in public spaces is becoming an increasingly important issue in society - just look at the moves to ban smoking in public places."
Mike Fisher, director of the British Association of Anger Management, said: "A reduction in the level of oxygen in an enclosed space leads to increasing feelings of panic.
"If on top of this you have the physical distress and discomfort of overcrowding, an individual can experience reactions such as anxiety, aggression, impatience and feelings of sickness."
But a spokesman for LU said the company was examining ways of improving ventilation.
He added: "This report is based on old research and supposition.
"An independent report by the Institute of Occupational Medicine in Edinburgh
in September 2003 concluded that it is very unlikely that tunnel dust on the
Underground has any serious adverse affect on the health of Tube passengers and
The Fereday Pollard report adds that the Tube carries three million passengers a day, accounting for 37.5% of all journeys across London's transport network.