University of York's 2B Technologies Dual Channel Ozone Monitor is a UV photometric gas analyser (254nm) which has the capability to measure the amount of ozone in the air from 2 ppb concentrations up to 250 ppm. The instrument precision is 1 ppbV or 2% of the reading for a 10s average. Due to both sample and reference flowing at the same time, the instrument has a fast response time of 2 seconds, the fastest UV-based ozone monitor available. The gas concentration is displayed in real time and is logged via a standard RS-232 interface and data can also be logged internally. The instrument is small, lightweight and low power making it ideal for aircraft and balloon measurements where high spatial resolution is desired. The 2 second data can be averaged to produce 10s, 1 minute, 5 minute and 1 hr data automatically.