I’m a bit confused
I already answered in another question so here: Photochemical smog occurs when sunlight strikes an atom of NOx, kicks off an individual atom of oxygen (O), which combines with oxygen gas (O2), to create ozone/photochemical smog (O3). VOCs also play a role in photochemical smog. Volatile Organic Compounds are pollutants that evaporate or sublimate at room temperature. They can come from daily items like aerosols, carpets, printers, etc.