title: Modeling indoor air pollution of outdoor origin in homes of SAPALDIA subjects in Switzerland.
abstract: Given the shrinking spatial contrasts in outdoor air pollution in Switzerland and the trends toward tightly insulated buildings, the Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA) needs to understand to what extent outdoor air pollution remains a determinant for residential indoor exposure. The objectives of this paper are to identify determining factors for indoor air pollution concentrations of particulate matter (PM), ultrafine particles in the size range from 15 to 300nm, black smoke measured as light absorbance of PM (PMabsorbance) and nitrogen dioxide (NO2) and to develop predictive indoor models for SAPALDIA. Multivariable regression models were developed based on indoor and outdoor measurements among homes of selected SAPALDIA participants in three urban (Basel, Geneva, Lugano) and one rural region (Wald ZH) in Switzerland, various home characteristics and reported indoor sources such as cooking. Outdoor levels of air pollutants were important predictors for indoor air pollutants, except for the coarse particle fraction. The fractions of outdoor concentrations infiltrating indoors were between 30% and 66%, the highest one was observed for PMabsorbance. A modifying effect of open windows was found for NO2 and the ultrafine particle number concentration. Cooking was associated with increased particle and NO2 levels. This study shows that outdoor air pollution remains an important determinant of residential indoor air pollution in Switzerland.
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: reto.meier@unibas.ch.
authors.forename: Reto
authors.initials: R
authors.lastname: Meier
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: christian.schindler@unibas.ch.
authors.forename: Christian
authors.initials: C
authors.lastname: Schindler
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: marloes.eeftens@unibas.ch.
authors.forename: Marloes
authors.initials: M
authors.lastname: Eeftens
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: inmaculada.aguilera@unibas.ch.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Aguilera
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: regina.ducret@unibas.ch.
authors.forename: Regina E
authors.initials: RE
authors.lastname: Ducret-Stich
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: alex.ineichen@unibas.ch.
authors.forename: Alex
authors.initials: A
authors.lastname: Ineichen
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: mark.davey@unibas.ch.
authors.forename: Mark
authors.initials: M
authors.lastname: Davey
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland; Centre for Environmental Science and Engineering, Indian Institute of Technology, Bombay Powai, Mumbai 400076, India. Electronic address: phuleria@gmail.com.
authors.forename: Harish C
authors.initials: HC
authors.lastname: Phuleria
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: nicole.probst@unibas.ch.
authors.forename: Nicole
authors.initials: N
authors.lastname: Probst-Hensch
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: m.tsai@unibas.ch.
authors.forename: Ming-Yi
authors.initials: MY
authors.lastname: Tsai
authors.affiliation: Swiss Tropical and Public Health Institute, Socinstrasse 57, P.O. Box, CH-4002 Basel, Switzerland; University of Basel, Petersplatz 1, CH-4003 Basel, Switzerland. Electronic address: nino.kuenzli@unibas.ch.
authors.forename: Nino
authors.initials: N
authors.lastname: Künzli
mesh_terms: D000328:Adult; D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution; D016902:Air Pollution, Indoor / Q000032:analysis*; D015331:Cohort Studies; D003296:Cooking; D004784:Environmental Monitoring; D005260:Female; D006798:Housing; D006801:Humans; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D012044:Regression Analysis; D013557:Switzerland
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter; D009585:Nitrogen Dioxide
keywords: Indoor air pollution; Multivariable regression models; Nitrogen dioxide; Particle number concentration; Particulate matter; SAPALDIA; Switzerland; Ultrafine particles