What are the harmful effects of photochemical smog and how can these be controlled ?

Harmful effects of photochemical smog:
(i) During the formation of photochemical smog, concentration of ozone, peroxyacylnitrate (PAN), aldehydes (RCHO) and ketones (R₂CO) build up in the atmosphere. All these compounds produce irritation in the eyes and also in the respiratory system.
(ii) They also damage many materials.
(iii) Ozone is particularly destructive to rubber.
(iv) NO₂ present gives a brown colour to the photochemical smog which reduces visibility.

Control of photochemical smog: Photochemical smog can be controlled or suppressed by:
(i) Installation of efficient catalytic converters in the automobiles to reduce photochemical smog i.e. it prevents the release of nitrogen oxides and hydrocarbon to the atmosphere.

(ii) Certain compounds which trap free radicals. When these compounds are sprayed in the atmosphere, they generate free radicals which readily combine with free radical precursors of photochemical smog.