ISLAMABAD, June 6: Air pollution remains the major threat to environment of major cities of the country, Economic Survey 2002- 03 of Pakistan says.

The major sources of pollution in the main urban centres are smoke-emitting vehicles, and haphazardly planned industrial sectors within the limits of metropolitan cities.

Air pollution levels in most populated cities are among the highest in the world. Auto and industrial emissions are the main source of polluted air.

Over the last two decades, the total number of motor vehicles on the road has jumped from 0.8 million to 4 million, showing an overall increase of more than 500 per cent (World Summit on Sustainable Development-WSSD Country Assessment Report, Ministry of Environment 2002). The average increase in the number of in Pakistan is about 12 per cent per annum, the economic survey said.

Motorcycles and rickshaws, due to their two-stroke engines, are the most inefficient in burning fuel and produce more emissions. Fortunately, the rickshaws have only tripled in numbers, but motorcycles and scooters have gone up more than seven fold in the last two decades.

However, 28.7 per cent of the total vehicles on road are running on CNG. With the improved design of new car engines and conversion of 300,000 vehicles to CNG, pollution level in many urban centres has started declining.

The levels of ambient particulates, smoke particulate and dust that cause respiratory diseases are generally twice the world average and more than five times as high in industrial countries even in Latin America. The combustion of coal is another main contributor of air pollution. The three main uses of coal are power, brick-kilns and domestic. Since 1998-99, the coal use has decreased gradually for all these three purposes, which is a healthy sign.

However, coal is being replaced by natural gas that should be used in a sustainable manner. The focus should also be on exploring renewable energy sources.

The efforts to address the environmental concerns at policy, planning, and development level, which gained momentum with the establishment of a high level inter-ministerial and multi- stakeholder committee called Pakistan Environment Protection Council, remained active during the fiscal year 2002-03.

The energy sector introduced lead-free petrol and since July 2002, all refineries in the country have supplying lead-free petrol and promoting clean fuels including CNG.

Moreover, chemical insecticides, fertilizers and solid wastes generated in urban areas are other important sources of pollution that have been mentioned in the Economic Survey.