Sulphur dioxide is not involved in global warming.

Chlorinated hydrocarbons are present in pesticides and are involved in biological magnification. These chemicals may be selectively accumulated by organisms to much larger concentrations than that can cause toxicity.

Sulphur trioxide can combine with hemoglobin and reduce the oxygen-carrying capacity of blood.

Lead can accumulate in the bones, distort RBCs and affect the oxygen-carrying capacity of blood.

Benzo(a)pyrene has shown probable evidence of carcinogenicity in humans. It is listed as a group I carcinogen by IARC.

PCBs do not cause blisters on skin, but they may change the skin pigmentation.

Hydrocarbons and nitrogen oxide combine together in the presence of ultraviolet rays to form photochemical smog. It is a thick dark or yellow fog that causes toxic effect on man, animals and plants.

Cotton dust causes byssinosis (brown lung disease). It commonly occurs in workers employed in yarn industries.

Electrostatic precipitation is used for particulate pollutants. When a gas containing aerosols is passed between two electrodes, aerosol particles get precipitated on the electrode.

Ground level ozone is formed by the reaction of volatile organic compounds with nitrogen oxide. It can cause respiratory diseases.

Both a and b are correct. Phaseolus vulgaris and Daucs carota can fix carbon monoxide and can reduce CO pollution.

Carbon monoxide is considered to be a non-greenhouse gas. Though CO absorbs infrared rays, it is highly unstable and does not significantly contribute to greenhouse effect. 

Algal bloom in the coastal areas due to increased nutrient loading from human activities is known as red tide. It is caused by a few species of dinoflagellates and is potentially harmful to human health. Red tide toxin can contaminate marine life and humans can become seriously ill by consuming them.

Siltation is the phenomenon by which the gills of fishes are deposited with silt. This causes heavy mortality among fishes.

PCBs are produced by burning plastics. They cause skin conditions like rashes and chloracne.