An ozone generator is a device that intentionally produces the gas ozone, which is a highly reactive gas containing three oxygen atoms. Ozone generators are often marketed as air purifiers and are designed to reduce the presence of airborne contaminants by oxidizing and eliminating them. However, ozone generators are not effective at removing particles such as dust and pollen from the air. Ozone generators can be small handheld devices or large-scale industrial models that can produce several hundred grams of ozone each hour. There are two types of ozone generators: corona discharge generators and UV light generators. Corona discharge generators create ozone by taking oxygen and forcing it through a high voltage metallic grid, while UV light generators use ultraviolet light to create ozone. Ozone generators are not safe for use in occupied spaces, as they can emit unsafe levels of ozone that can be harmful to human health. The EPA and other governmental agencies advise against the use of ozone generators in spaces occupied by people or animals.