Abstract: A method and apparatus for regulating an amount of ozone incident to an air stream of an air purifier. The air purifier has a number of ultra violet light lamps, a catalyst, a first sensor, a second sensor, a ventilating duct, an array of baffles and a fan. The first sensor and second sensor detect a first and a second level of contamination of the air stream and, in response thereto, the array of baffles increase or decrease the travel path of the air stream for exposure by the UV lamps. The UV lamps and catalyst also move with respect to each other for varying the amount of exposure of the UV lamps to the contaminated air stream to regulate the ozone incident on the air stream. The improved apparatus improves the efficiency by regulating the amount of ozone incident to an air stream for varying cooking loads.