This lecture covers the composition of the atmosphere, including trace components like nitrogen, oxygen, carbon dioxide, and others. It discusses the motivation for measuring trace gases, such as ozone depletion, global warming, and acid rain. The course aims to provide an overview of atmospheric trace compounds, understanding monitoring techniques, and practical measurement exercises. The schedule includes topics on measurement strategies, historical air pollution development, and different measurement techniques like in-situ and remote sensing. It also addresses the importance of location and time resolution in air quality measurements.