What are the harmful effects of photochemical

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

Photochemical smog consists of ${{O}{3}}$, NO, acrolein, formaldehyde and PAN.
{3}}$ and NO irritate the nose
and throat and their high concentration causes headache, chest pain, dryness of throat, cough, difficulty in breathing. Aldehydes and PAN cause irritation in eyes. PAN is highly toxic substance to plants and causes bronzing of tender leaves. Ozone also affects the rubber articles and causes cracking and ageing.
Control of photochemical smog :If primary precursors of photochemical smog such as hydrocarbons and ${{NO}{2}}$ are controlled, the secondary precursors such as
{3}}$ and PAN will automatically be reduced. In automobiles, catalytic converters are used to prevent the release of nitrogen oxide and hydrocarbons to the atmosphere.
Certain plants such as pinus, juniparus, etc., can metabolise nitrogen oxide and can help in reducing photochemical smog.