Methods:
Emissions from vegetation are combined with a flow of ozone-enriched air and allowed to react in a flow reactor. Ozone is measured upstream and downstream of the reactor with a single instrument. In the standard configuration of a UV absorption ozone monitor, ozone-containing air and scrubbed air (ozone-free air) are either measured sequentially (one optical cell) or in parallel (two cell instruments), with the ozone mole fraction then determined following the Beer–Lambert law.