sentence: Many secondary pollutants are made when a primary pollutant reacts with sunlight.
sentences_before: Secondary pollutants are pollutants that are made from chemical reactions when pollutants mix with other primary pollutants or natural substances like water vapor.
sentences_after: Ozone and smog are secondary pollutants. Ozone is a gas that is helpful and takes in harmful rays from the sun. When it is near the ground, though, ozone is a dangerous pollutant that influences the health of all organisms.
concept_name: secondary pollutant
headings: Air pollution Types of air pollution