London: Air pollution plays a well-documented role in asthma and heart attacks and now, a new study shows that it not only worsens them, but also is their direct cause.

London's Queen Mary College's John Grigg dubbed air pollution as the "modern invisible killer," adding that it can change cells in lungs, which can lead to allergic reactions that cause asthma, the Mirror reported.

Grigg noted, "We should all be worried about it and in my view the levels of air pollution we're exposed to are a public health disaster. Pollution is not only making asthma worse, it's causing asthma."

Grigg, whose 10-year study features in a Channel 4 Dispatches programme, noted that since children are nearer to the ground, they are nearer to the emissions from traffic and hence, are at greater risk as they breathe faster.

A Dispatches reporter found a key part of air pollution, nitrogen dioxide, was four times the EU limit at Birmingham New Street station, which is used by 170,000 people a day. Another study based on 3,000 children also showed air pollution harms ¬youngsters' brains.

Researcher Jordi Sunyer tells the programme that they discovered that the brain reacts much more slowly in children from schools with high pollution.

Professor David Newby from Edinburgh Clinical Research facility said that when there are high pollution days, people are much more likely to present with heart attacks.