Personal, Indoor, and Outdoor Concentrations of Fine and Ultrafine Particles Using Continuous Monitors in Multiple Residences

Abstract

Concentrations of airborne continuous fine particulate matteror (PM2.5), black carbon (BC), and ultrafine particles (UFP) werecontinuously measured over 5 days in winter and summer both indoorsand outdoors at residences for forty-eight adults in 2005 andforty-seven asthmatic children in 2006. During 2006, personal concentrationsof PM2.5 were also measured continuously. All 4 continuousinstruments employed performed well both in laboratory andfield conditions. Mean outdoor concentrations of PM2.5, BC, andUFP were significantly higher than either indoor or personal concentrations.Air exchange rates were low (median value only 0.2/h),there was widespread use of central forced air and high-qualityfurnace filters. Outdoor concentrations of all particle-related pollutantsshowed overnight decreases followed by increases duringthe morning rush hours. Afternoon concentrations increased forUFP and decreased for BC, with PM2.5 staying about the same. Between5:00 pm and 7:00 pm, indoor UFP and PM2.5 concentrationsexceeded their mean daily values by 160% and 60%, respectively,suggesting that cooking is an extremely important source for thesetwo pollutants. However, BC values did not increase at these hours.The highest indooroutdoor ratios were observed for UFP suggestingthat indoor sources were relatively more important for UFPthan for other particle components. BC measurements in Windsoragreed moderately well (R2 = 41%) with an independent measureof elemental carbon (EC) in Detroit. This large residential airpollution study has provided data making it possible to identifyshort-term variations and possible sources that can influence therelationships between pollutants and environments.