EVERYDAY SCIENCE

Detailed explanation-1: -What is photochemical smog? Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight, creating a brown haze above cities. It tends to occur more often in summer, because that is when we have the most sunlight.

Detailed explanation-2: -These impacts mainly occur within the regions where tropospheric ozone precursors are emitted, and so disproportionally affect the Northern Hemisphere. Tropospheric ozone is a major component of smog, which can worsen bronchitis and emphysema, trigger asthma, and permanently damage lung tissue.

Detailed explanation-3: -Among the pollutants involved in photochemical smogs are ozone, nitrogen dioxide and peroxyacyl nitrate (PAN). The nitrogen dioxide, and other oxides of nitrogen, are primary pollutants produced by dissociation in combustion reactions, and both ‘prompt’ and ‘thermal’ NOx can be involved in the reactions.

Detailed explanation-4: -Secondary pollutants are harder to control because they have different ways of synthesizing and the formation are not well understood. They form naturally in the environment and cause problems like photochemical smog.