KARACHI: Pakistan is a country of 188 million people with average population density of 236 persons per square kilometre, which is higher as compared to many other developing countries. The country has very high migration rate to urban centres which has made the cities very congested and turned the civic infrastructure inadequate, according to new Pakistan Economic Survey 2013-14.
Air quality data recorded in cities confirmed presence of high concentration of suspended particulate matter in air (2-3.5 times higher than the safe limit). Oxides of Nitrogen (NOx) is continuously increasing in major cities mainly due to increased number of CNG operated vehicles.
Formation of photo-chemical smog and haze is a common phenomenon in our cities. Most urban citizens rely either on their private motor vehicles or two wheelers or the informal transport sector for urban transport. This has led to a sharp increase in private vehicle ownership. The surge in the demand for private vehicles originated from the increasing affordability on the one hand and availability of vehicle financing from the banking system on the other.
Amongst these, diesel vehicles using crude diesel oil and motorcycles and rickshaws are of most serious concern. Due to overloading, faulty injection nozzles and weak engines, diesel vehicles emit excessive carbon (visible smoke) while motorcycles and rickshaws, due to their two-stroke engines, are the most inefficient in burning fuel and thus contribute most to emissions. The number of motorcycles/scooters is growing fastly in Pakistan and has increased by 133.8 percent in 2012-13 when compared with the year 2001-02. Rickshaws have grown by 24.4 percent in 2012-13.
The main causes of air pollution are the abrupt increase in the number of vehicles, inefficient automotive technology, u se of unclean fuels, uncontrolled emissions of industrial units, emissions of brick kilns, the burning of garbage and the presence of dust. Vehicular emissions in all the major cities of Pakistan are the primary source of air pollution.
The transport sector is the largest user of petroleum products. The use of adulterated fuel and poorly maintained vehicles are some of the reasons for excessive and highly toxic emissions from vehicles. Brick kilns are another source of pollution in many areas. The use of low-grade coal and old tires in brick kilns generates dense black smoke and other kinds of emissions. The main pollutants from these industries are particulate matter, and sulphur- and nitrogen oxides, which are emitted by burning fuels.
The use of coal has increased by 34.3 percent for brick kilns in 2012-13 when compared with year 2001-02. Like other forms of air pollution, the magnitude of industrial air pollution has not been fully assessed but sporadic surveys have been carried out in the country by some governmental institutions and scientists in a few major cities. The industrial sector in Pakistan is likely to expand further in future due to a liberal government policy. Almost all metropolitan cities have industrial estates, where a cluster of industries of different types exist. Cement, fertilizer, sugar units, and power plants a considered to be the most air polluting industries of Pakistan.
Many of these are located either in the rural areas or are in the vicinity of secondary towns. Those located in the vicinity of towns cause urban air pollution.
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