Particulate Matter: New Chapter on the Next Generation of Aerosols

Abstract

Scientists have known for decades that carbonaceous molecules emitted by cars, factories, and ships can react chemically to form new pollutants called secondary organic aerosols (SOA). Until recently they thought these offspring constituted only a small part of the pollution plume [see “Ship Sulfate an Unexpected Heavyweight,” EHP 116:A475 (2008)]. So when researcher Jose-Luis Jimenez of the University of Colorado at Boulder and colleagues analyzed the particle content of the air of Riverside, California, about 50 miles east of Los Angeles, they were surprised to find that only 10–30% came from smokestacks and tailpipes—the rest was SOA generated in the atmosphere. The findings, reported 15 October 2008 in Environmental Science & Technology, add to growing suspicions that people may be exposed to substantial levels of unregulated health-threatening pollutants.