The main sources of air pollution in the State are emissions from industrial stacks, vehicles and power plants, burning of fuel in domestic sector and burning of agricultural residues in the harvesting season in the fields by farmers. Thus, the various types of pollution affecting the ambient air quality in Punjab are as under:
Industrial Pollution
All industries are categorized into Red (highly polluting) and Green (Moderately, mildly or non-polluting) categories. The Red category industries require environmental clearance from Competent State Authority of the Department of Environment. Many of these industries use coal or rice husk as fuel. Together these contribute to suspended particulates, oxides of nitrogen and sulfur, organic compounds and other pollutants in the air.
Category wise air polluting industries in Punjab
| Name of Industry | Major Air Pollutants |
| Rice, Sugar, Food Products | Particulates, CO2, SO2, NOx |
| Beverages | Particulates, Odour |
| Cotton/Woolen/Synthetic/Textile/Dying etc. | Particulates |
| Paper Products & Printing | Particulates, mercaptans |
| Leather & Leather Products | Particulates, Odour |
| Rubber & Plastic Products | Particulates, Odour, VOCs |
| Chemical Products | Cl2, HCl, Acid mist, Acid fumes, Hydrocarbons |
| Non-Metallic Mineral Products | Particulates |
| Metal Products | Metallic Particulates, CO, SO2, Acid Mist |
| Transport Equipments & Parts | Particulates |
| Brick Kilns | Particulates, SO2, CO |
| Pharmaceuticals | Odour, Particulates |
| Rolling, forging & galanizing units | Particulates |
| Fertilizer, Vanaspati, Thermal, Cement, etc. | Odour, Particulates |
Vehicular Pollution
Vehicular emissions are of particular concern since these are ground level sources and thus have the maximum impact on the human population and other biotic components. The major pollutants released as vehicle/fuel emissions are carbon monoxide, nitrogen oxides, photochemical oxidants, air toxics namely benzene, aldehydes, 1-3 butadiene, lead, particulate matter, hydrocarbon, oxides of sulphur and polycyclic aromatic hydrocarbons.
While the predominant pollutants in petrol/gasoline driven vehicles are hydrocarbons and carbon monoxide, the predominant pollutants from the diesel based vehicles are oxides of nitrogen and particulates. As per studies by Central Pollution Control Board, vehicular emissions are responsible for most of hydrocarbons (90-95%) and carbon monoxide (70-80%) emissions.
Factors responsible for Vehicular Pollution: Increase in vehicular number is itself an indicator of increase in vehicular pollution over the years in the state. Besides increase in the number of vehicles the poor maintenance of vehicles is major reason for the high vehicular emissions. Majority of the three-wheelers, fitted with diesel engines, use diesel and kerosene as fuel, which causes lot of pollution in the State. Improper traffic management and road conditions also contribute to pollution.
Air Pollution from Agricultural & Domestic Practices Pollution from agricultural activities also adversely affects the state’s environment. The state produces about 20 million tons of rice straw, and 17 million tons of wheat straw every year, a part of which (about 81% of rice straw and 48% of wheat straw) is burnt in the fields to make way for the next crop. Besides leading to loss of soil fertility, it causes severe air pollution especially during the months of March-April and October-November. The smoke also impairs visibility which can cause road accidents. Though LPG is the main source of domestic fuel in urban areas, however, cow dung cakes and wood are still used in rural areas and slums. Further, due to high per capita income and adoption of modern life style, use of air conditioners and refrigerators in the state is increasing rapidly. This contributes to air pollution by ozone depleting substances. Further, since the state faces acute power shortage problem, use of diesel/kerosene gen-sets in domestic and commercial sector is rampant.
Noise Pollution Increasing urbanization and industrialization and high density of traffic in Punjab has resulted in increased noise levels in the environment leading to noise pollution. The ordinary citizens particularly in Punjab and the Northern Plains also contribute towards noise pollution during religious ceremonies and festivals.