Fine and ultrafine particle levels determined during everyday activities : the PM-CARE project

Exposure to particle number (particles >0.02 μm in aerodynamic diameter, a.d.) and particle mass levels (PM0.5 , PM1 , PM2.5 and PM10) were determined on 82 non-smoking senior volunteers living in urban and suburban areas of Milan, during the warm and cold seasons of 2005-2006. Measuring devices, comprehending optical counters (6-channel OPC and CPC), a 4-stage cascade impactor, CO and O3 monitors and a NO2 passive sampler, were mounted on trolleys (25kg), especially equipped to provide 24h self-contained air monitoring. Subjects’ activities were individually recorded on timetables, used also for clinical purposes (see Fanetti et al.). When required, outdoor transfers by car or afoot were assisted by project personnel. 24h-average particle number and mass (PM10) concentration means were 19.500 #/cm3 and 41.4 µg/m3 in summer (1913 hours) and 26.600 #/cm3 and 62.0 µg/m3 in winter (1894 hours), with a mean seasonal contribution of PM0.5 to PM10 of 54% and 68%, respectively. Data plots logged by particle counters were apportioned and separately examined according to the most common activities emerging from the timetable. Resulting particle number concentrations are here presented as the mean percent deviation from individual 24h-averaged levels, given as Activity: [a.d. 0.3–0.5 µm] and [a.d. >0.02] (total hours monitored; number of subjects). Home at rest: -1% and -20% (1419; 76), Domestic activities: +6% and +7% (307; 75), Flame cooking: +14% and +97% (293; 72), Workplace activities: +18% and -10% (104; 12), Sleep: -7% and -51% (1170; 78), Moving by car: +46% and +141% (103; 81), Promenade: +52% and +27% (66; 32). With the exception of domestic and workplace activities, which could not be better specified, the results reported are indicative of human PM exposure pattern experienced in urban and suburban areas. Substantial increases of overall particle counts are associated with flame cooking and vehicle displacements, whereas PM0.5 levels seem to be mainly associated with outdoor sources.