Of or pertaining to chemical action of light, or produced by it; as, the photochemical changes of the visual purple of the retina.

smog A colourless air pollution that occurs mostly in summer. It is produced when pollutants such as nitrogen oxides and organic compounds (produced by burning fossil fuels) react with sunlight in the atmosphere to form a gas called ozone.

of or relating to or produced by the effects of light on chemical systems

of, relating to, or resulting from the chemical action of radiant energy and especially light