Tropospheric OH formation by ozonolysis of terpenes

The formation of hydroxyl radicals in the reaction of ozone with a number of monoterpenes has been searched for under true atmospheric conditions. In all cases OH is produced showing efficiencies in some cases approaching unity, that is for each ozone molecule that reacts about one OH molecule is detected. This observation makes the ozonolysis of the monoterpenes a significant source of OH in the troposphere, which competes under favourable conditions with the radiation-based production via ozone photolysis in the presence of water vapor. Another product formed in this reaction which has been observed simultaneously with OH is formaldehyde.