The correct answer is option 3, Polyaromatic hydrocarbons (PAHs), is not a component of photochemical smog.

1. Ozone is a major component of photochemical smog. It is formed when nitrogen oxides (NOx), volatile organic compounds (VOCs), and sunlight interact. Ozone is a harmful pollutant that can cause respiratory issues and contribute to the formation of smog.

2. Peroxyacetyl nitrate (PAN) is also a component of photochemical smog. It is formed when volatile organic compounds react with nitrogen oxides in the presence of sunlight. PAN is an irritant to the eyes, nose, and throat.

4. Nitric oxide (NO) is another component of photochemical smog. It is primarily emitted from vehicle exhaust and power plants. In the presence of sunlight and other pollutants, nitric oxide can convert into nitrogen dioxide (NO2), a harmful gas that contributes to the formation of smog.

In summary, while options 1, 2, and 4 are all components of photochemical smog, option 3, Polyaromatic hydrocarbons, is not. PAHs are a group of organic compounds that are more commonly associated with partic