New Instruments Help Size up Aerosols

Atmospheric scientists have speculated that aerosols, which impact climate and air quality, can form from particle clusters that start out smaller than 3 nm in diameter. But until now, they lacked instruments capable of detecting such particles. Markku Kulmala of the University of Helsinki, in Finland, and colleagues describe new equipment that breaks through that limit (Science, DOI: 10.1126/science.1144124). The researchers' ion spectrometer and particle counters can measure atmospheric concentrations of both neutral and ionic clusters, which are two physically distinguishable types of building blocks thought to make up aerosols. Using atmospheric measurements from Hyytiälä, Finland, they demonstrate that neutral clusters measure approximately 2 nm and that the concentration of neutral clusters is greater than that of ionic clusters. The researchers write that the new instruments should provide more opportunities for including aerosols in regional and global air-quality models.