air pollution levels in Pakistan's highly populated cities are among the highest in the world. And the levels are on the rise, raising health concerns, says a Pakistan government report.

The levels of ambient particulates, smoke particulates and dust, which cause respiratory diseases, are twice the world's average and more than five times as high as that in industrialised and Latin American countries, says the Economic Survey of Pakistan 2005-2006, released in June.

The survey found that pollution levels in Pakistan's cities had either crossed safe limits or reached the threshold value, with the presence of suspended particulate matter (spm) in the ambient air being very high. The report says the major sources of spm in the country are vehicles, industry, burning of solid waste, brick kilns and natural dust. Growing energy demand, increasing industrial and domestic demand and a fast growing transport sector contribute to the pollution.

In cities, widespread use of low quality fuel, combined with a dramatic expansion in the number of vehicles on roads, is a major contributor. The number of vehicles has jumped from 0.8 million to about 4.0 million in 20 years