The abundance, potential precursors, and main formation mechanisms of nitrogen-containing organic compounds (NOCs) in PM_2.5 during winter were compared among cities with different energy consumption patterns. The aerosol NOC pollution during winter in China is closely associated with the intensity of precursor emissions and the aqueous-phase processes. Our results highlight the importance of emission reduction strategies in controlling aerosol NOCs pollution during winter in China.

Carbon dioxide (CO₂) is a very important atmospheric pollutant, and to better understand the gas's source and sink dynamics, a mid-cost sensor network hosting 26 sites was deployed in and around Zurich, Switzerland. The sensor measurement performance was quantified, and natural and anthropogenic CO₂ emission sources were explored with a focus on what drives high CO₂ levels. The observations will be used further by others to validate what is thought to be known about CO₂ emissions in the region.