title: Toxicity and elemental composition of particulate matter from outdoor and indoor air of elementary schools in Munich, Germany.
abstract: Outdoor particulate matter (PM(10)) is associated with detrimental health effects. However, individual PM(10) exposure occurs mostly indoors. We therefore compared the toxic effects of classroom, outdoor, and residential PM(10). Indoor and outdoor PM(10) was collected from six schools in Munich during teaching hours and in six homes. Particles were analyzed by scanning electron microscopy and X-ray spectroscopy (EDX). Toxicity was evaluated in human primary keratinocytes, lung epithelial cells and after metabolic activation by several human cytochromes P450. We found that PM(10) concentrations during teaching hours were 5.6-times higher than outdoors (117 ± 48 μg/m(3) vs. 21 ± 15 μg/m(3), P < 0.001). Compared to outdoors, indoor PM contained more silicate (36% of particle number), organic (29%, probably originating from human skin), and Ca-carbonate particles (12%, probably originating from paper). Outdoor PM contained more Ca-sulfate particles (38%). Indoor PM at 6 μg/cm(2) (10 μg/ml) caused toxicity in keratinocytes and in cells expressing CYP2B6 and CYP3A4. Toxicity by CYP2B6 was abolished with the reactive oxygen species scavenger N-acetylcysteine. We concluded that outdoor PM(10) and indoor PM(10) from homes were devoid of toxicity. Indoor PM(10) was elevated, chemically different and toxicologically more active than outdoor PM(10). Whether the effects translate into a significant health risk needs to be determined. Until then, we suggest better ventilation as a sensible option.
  
  
  CONCLUSIONS
  Indoor air PM(10) on an equal weight base is toxicologically more active than outdoor PM(10). In addition, indoor PM(10) concentrations are about six times higher than outdoor air. Thus, ventilation of classrooms with outdoor air will improve air quality and is likely to provide a health benefit. It is also easier than cleaning PM(10) from indoor air, which has proven to be tedious.
authors.affiliation: ZAUM-Center of Allergy and Environment, Helmholtz Zentrum München/Technische Universität München, Munich, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Oeder
authors.forename: S
authors.initials: S
authors.lastname: Dietrich
authors.forename: I
authors.initials: I
authors.lastname: Weichenmeier
authors.forename: W
authors.initials: W
authors.lastname: Schober
authors.forename: G
authors.initials: G
authors.lastname: Pusch
authors.forename: R A
authors.initials: RA
authors.lastname: Jörres
authors.forename: R
authors.initials: R
authors.lastname: Schierl
authors.forename: D
authors.initials: D
authors.lastname: Nowak
authors.forename: H
authors.initials: H
authors.lastname: Fromme
authors.forename: H
authors.initials: H
authors.lastname: Behrendt
authors.forename: J T M
authors.initials: JT
authors.lastname: Buters
mesh_terms: D016902:Air Pollution, Indoor / Q000009:adverse effects* / Q000032:analysis*; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism; D001711:Biotransformation; D002119:Calcium Carbonate / Q000032:analysis / Q000633:toxicity; D002460:Cell Line; D002478:Cells, Cultured; D002648:Child; D065702:Cytochrome P-450 CYP2B6; D051544:Cytochrome P-450 CYP3A / Q000378:metabolism; D005858:Germany; D006798:Housing; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis* / Q000633:toxicity*; D012574:Schools; D012825:Silicon / Q000032:analysis / Q000633:toxicity; D013455:Sulfur / Q000032:analysis / Q000633:toxicity
chemical_list: D052638:Particulate Matter; D013455:Sulfur; D001189:Aryl Hydrocarbon Hydroxylases; C585599:CYP2B6 protein, human; D065702:Cytochrome P-450 CYP2B6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D010089:Oxidoreductases, N-Demethylating; D002119:Calcium Carbonate; D012825:Silicon