It has been advised that expecting mothers living in city should avoid inhaling traffic congested air as the polluted air contains an increased amount of polycyclic aromatic hydrocarbons (PAH), ammonium nitrate and diesel fumes, which leads to premature deliveries and is also found to be harmful for both mum and baby.

The University Of California research that got published in the `Environmental Health' journal revealed that they have followed 100, 000 expecting mothers in Los Angeles County for 22 months from 2004 to 2006 April. And evaluated their children birth and level of air pollution to which they were exposed. Exposition level was found by taking figures from air pollution department of the concerned area.

After evaluating them, it was found that PAH increases the risk of premature birth by 30%, ammonium nitrate particles enhances the risk factor by 21% and diesel fumes omitted chemicals elevates the danger by 10%.

It has also been discovered that atmosphere of a place plays an important role in dispersion of air pollution level, as summers is purer than winters to breathe in at coastal areas.

The solution to this problem is to get `accurate modeling of local and regional spatial and temporal air pollution should be incorporated into pollution policies', said researcher Dr. Beate Ritz.