Atmospheric aerosols such as smoke, fog, and mist are made of fine solid or liquid particles suspended in air. In the lower atmosphere aerosols play a major role in controlling air quality, as well as in scattering and absorbing sunlight. This interaction of aerosols with light varies widely and depends on their complex chemical composition that rapidly changes under the highly reactive conditions found in the atmosphere. Importantly, the mysterious formation of carbon-containing atmospheric particles has intrigued atmospheric scientists during the last decade. This issue demands a thorough understanding of the mechanisms of atmospheric reactions as tackled in a new laboratory study entitled Reactivity of Ketyl and Acetyl Radicals from Direct Solar Actinic Photolysis of Aqueous Pyruvic Acid published in the Journal of Physical Chemistry A.