Understanding natural emissions from the Earth's vegetation and their effect on air quality and climate.

Trees emit compounds that affect air quality and climate, such as terpenes (hydrocarbons), which help form clouds and reflect the sun's rays leading to a cooler climate, but also raise ozone levels in the lower atmosphere where it is a pollutant. NPL provides the primary standards that are used by monitoring stations across the Earth and is working to improve the lower detection limits of a variety of terpenes.