Final answer:
Secondary pollutants are formed from the reactions between primary pollutants and atmospheric chemicals, with ozone being a notable example. They are not emitted directly, unlike primary pollutants, but can still have significant environmental and health impacts.
Step-by-step explanation:
Secondary pollutants are contaminants in the environment that do not directly emerge from a source. Instead, they form when primary pollutants, which are discharged directly into the air in a harmful form, react with other chemicals present in the atmosphere. A classic example involves ground-level ozone, which forms over urban areas through reactions driven by sunlight, between nitrogen oxides (NOx) and volatile organic compounds (VOCs). In contrast to primary pollutants, secondary pollutants are not emitted directly but arise from the chemical interactions that occur after primary pollutants have entered the air.
Regarding the options given, the correct answer is B, which states that secondary pollutants are created from the reaction of primary pollutants and other chemicals. These reactions can occur when primary pollutants like NOx and VOCs interact with sunlight, resulting in the formation of new, often more harmful pollutants, such as ozone. Therefore, secondary pollutants can have significant impacts on the environment and human health, despite not being emitted directly into the atmosphere.