Environment of Pakistan
The Air pollution is the release of chemicals and particulates into the atmosphere. Common gaseous pollutants include carbon monoxide, sulfur dioxide, chlorofluorocarbons (CFCs) and nitrogen oxides produced by industry and motor vehicles. Photochemical ozone and smog are created as nitrogen oxides and hydrocarbons react to sunlight. Particulate matter, or fine dust is characterized by their micrometre size PM to PM. The air in Karachi is rapidly polluted by automobile smoke, especially Rickshaws and Buses, industrial emissions, open burning of garbage, house fires, and other particles but the government and environment organizations seems non-serious to tackle the issue timely.
The two-stroke engines on rickshaws and motorcycles are one of the major polluters of air in Karachi and the rest of Pakistan. The two-stroke engines as well as defective or unturned vehicles are major polluters with carbon dioxide emissions. Two-stroke engines as well as defective vehicles using substandard lubricant are major emitters of sulfur dioxide and smoke. Automobiles operating on compressed natural gas and liquefied petroleum gas are major air polluters.
Smog
Delhi is the most polluted city in the world and according to one estimate, air pollution causes the death of about 10,500 people in Delhi every year. During 2013–14, peak levels of fine particulate matter (PM) in Delhi increased by about 44%, primarily due to high vehicular and industrial emissions, construction work and crop burning in adjoining states. Delhi has the highest level of the airborne particulate matter, PM2.5 considered most harmful to health, with 153 micrograms. Rising air pollution level has significantly increased lung-related ailments (especially asthma and lung cancer) among Delhi's children and women. The dense smog in Delhi during winter season results in major air and rail traffic disruptions every year. According to Indian meteorologists, the average maximum temperature in Delhi during winters has declined notably since 1998 due to rising air pollution.
Environmentalists have criticised the Delhi government for not doing enough to curb air pollution and to inform people about air quality issues. Most of Delhi's residents are unaware of alarming levels of air pollution in the city and the health risks associated with it. Since the mid-1990s, Delhi has undertaken some measures to curb air pollution – Delhi has the third highest quantity of trees among Indian cities and the Delhi Transport Corporation operates the world's largest fleet of environmentally friendly compressed natural gas (CNG) buses. In 1996, the Centre for Science and Environment (CSE) started a public interest litigation in the Supreme Court of India that ordered the conversion of Delhi's fleet of buses and taxis to run on CNG and banned the use of leaded petrol in 1998. In 2003, Delhi won the United States Department of Energy's first 'Clean Cities International Partner of the Year' award for its "bold efforts to curb air pollution and support alternative fuel initiatives". The Delhi Metro has also been credited for significantly reducing air pollutants in the city.