Peoxyacetyl nitrate (PAN), an eye irritant is produced by

The photochemical smog produces peroxyacetyl nitrate (PAN), an eye irritant. The photo signifies light in photochemical smog, while smog is a combination of smoke and fog. The levels of NO and hydrocarbons rise in the morning, followed by an increase in nitrogen dioxide. When this nitrogen dioxide is exposed to sunlight, it produces ozone and a molecule known as PAN, or peroxyacetyl nitrate. Photochemical pollution causes eye discomfort, impaired vision, respiratory problems, sore throats, and other symptoms.