Local- and regional-scale air pollution modelling (PM(10)) and exposure assessment for pregnancy trimesters, infancy, and childhood to age 15 years: Avon Longitudinal Study of Parents And Children (ALSPAC)

We established air pollution modelling to study particle (PM(10)) exposures during pregnancy and infancy (1990–1993) through childhood and adolescence up to age ~15 years (1991–2008) for the Avon Longitudinal Study of Parents And Children (ALSPAC) birth cohort. For pregnancy trimesters and infancy (birth to 6 months; 7 to 12 months) we used local (ADMS-Urban) and regional/long-range (NAME-III) air pollution models, with a model constant for local, non-anthropogenic sources. For longer exposure periods (annually and the average of birth to age ~8 and to age ~15 years to coincide with relevant follow-up clinics) we assessed spatial contrasts in local sources of PM(10) with a yearly-varying concentration for all background sources. We modelled PM(10) (μg/m(3)) for 36,986 address locations over 19 years and then accounted for changes in address in calculating exposures for different periods: trimesters/infancy (n = 11,929); each year of life to age ~15 (n = 10,383). Intra-subject exposure contrasts were largest between pregnancy trimesters (5(th) to 95(th) centile: 24.4–37.3 μg/m(3)) and mostly related to temporal variability in regional/long-range PM(10). PM(10) exposures fell on average by 11.6 μg/m(3) from first year of life (mean concentration = 31.2 μg/m(3)) to age ~15 (mean = 19.6 μg/m(3)), and 5.4 μg/m(3) between follow-up clinics (age ~8 to age ~15). Spatial contrasts in 8-year average PM(10) exposures (5(th) to 95(th) centile) were relatively low: 25.4–30.0 μg/m(3) to age ~8 years and 20.7–23.9 μg/m(3) from age ~8 to age ~15 years. The contribution of local sources to total PM(10) was 18.5%–19.5% during pregnancy and infancy, and 14.4%–17.0% for periods leading up to follow-up clinics. Main roads within the study area contributed on average ~3.0% to total PM(10) exposures in all periods; 9.5% of address locations were within 50 m of a main road. Exposure estimates will be used in a number of planned epidemiological studies.