In this subtitle, the following terms have the meanings indicated. “Air pollution” means the presence in the outdoor atmosphere of any odor, solid, vapor, liquid, gas, or other substance in such quantities and of such duration that it:can be predicted with reasonable certainty to be injurious to property or to human, plant, or animal life; or unreasonably interferes with the proper enjoyment of the property of others or with the comfort of the public. “Emission standard” means a requirement that limits the quantity, quality, rate, or concentration of emissions from a source. “Emission standard” includes any requirement that relates to the operation or maintenance of a source to assure continuous emission reduction. “Source” means any equipment, process, structure, space, material, or activity that contributes to air pollution. Ord. 99-548