title: Ultrafine particles: exposure and source apportionment in 56 Danish homes.
abstract: Particle number (PN) concentrations (10-300 nm in size) were continuously measured over a period of ~45 h in 56 residences of nonsmokers in Copenhagen, Denmark. The highest concentrations were measured when occupants were present and awake (geometric mean, GM: 22.3 × 10(3) cm(-3)), the lowest when the homes were vacant (GM: 6.1 × 10(3) cm(-3)) or the occupants were asleep (GM: 5.1 × 10(3) cm(-3)). Diary entries regarding occupancy and particle related activities were used to identify source events and apportion the daily integrated exposure among sources. Source events clearly resulted in increased PN concentrations and decreased average particle diameter. For a given event, elevated particle concentrations persisted for several hours after the emission of fresh particles ceased. The residential daily integrated PN exposure in the 56 homes ranged between 37 × 10(3) and 6.0 × 10(6) particles per cm(3)·h/day (GM: 3.3 × 10(5) cm(-3)·h/day). On average, ~90% of this exposure occurred outside of the period from midnight to 6 a.m. Source events, especially candle burning, cooking, toasting, and unknown activities, were responsible on average for ~65% of the residential integrated exposure (51% without the unknown activities). Candle burning occurred in half of the homes where, on average, it was responsible for almost 60% of the integrated exposure.
authors: International Centre for Indoor Environment and Energy, Dept. of Civil Engineering, Technical University of Denmark , Nils Koppels Allé 402, 2800-Lyngby, Denmark.
authors: Gabriel
authors: G
authors: Bekö
authors: Charles J
authors: CJ
authors: Weschler
authors: Aneta
authors: A
authors: Wierzbicka
authors: Dorina Gabriela
authors: DG
authors: Karottki
authors: Jørn
authors: J
authors: Toftum
authors: Steffen
authors: S
authors: Loft
authors: Geo
authors: G
authors: Clausen
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D003296:Cooking; D003718:Denmark; D004784:Environmental Monitoring; D006798:Housing; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*
chemical_list: D052638:Particulate Matter