THEME ORIGINALLY

Tropospheric ozone is formed by the action of sunlight on nitrogen dioxide in the presence of volatile organic compounds (VOCs). Control of ozone concentration relies on controlling emissions of these ozone precursors, with emphasis on nitrogen oxides (NOx) or VOCs (or both) depending on their relative importance, i.e. whether ozone production is NOx or VOC limited. Globally, VOC emissions are dominated by biogenic sources, with limited options for control, unlike the anthropogenic sources for which (at least in Europe and North America) controls have been implemented.

Primary location: United Kingdom