Exposure to traffic-related particle matter and effects on lung function and potential interactions in a cross-sectional analysis of a cohort study in west Sweden.

Objectives: To investigate the long-term effects of source-specific particle matter (PM) on lung function, effects of Surfactant Protein A (SP-A) and glutathione S-transferase (GST) genes GSTP1 and GSTT1 gene variants and effect modification by single-nucleotide polymorphism (SNP) genotype.

Design: Cohort study with address-based annual PM exposure assigned from annual estimates of size (PM, PM and PM) and source-specific (traffic, industry, marine traffic and wood burning) dispersion modelling.

Setting: Gothenburg, Sweden.

Participants: The ADult-Onset asthma and NItric oXide Study had 6685 participants recruited from the general population, of which 5216 (78%) were included in the current study with information on all variables of interest. Mean age at the time of enrolment was 51.4 years (range 24-76) and 2427 (46.5%) were men.

Primary And Secondary Outcome Measures: The primary outcome was forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV). Secondary outcome measures were effects and gene-environment interactions of SP-A and GSTT1 and GSTP1 genotypes.

Results: Exposure to traffic-related PM and PM was associated with decreases in percent-predicted (% predicted) FEV by -0.48% (95% CI -0.89% to -0.07%) and -0.47% (95% CI -0.88% to -0.07%) per IQR 3.05 and 2.47 µg/m, respectively, and with decreases in % predicted FVC by -0.46% (95% CI -0.83% to -0.08%) and -0.47% (95% CI -0.83% to -0.10%). Total and traffic-related PM was strongly associated with both FEV and FVC by -0.53 (95% CI -0.94 to -0.13%) and -0.43% (95% CI -0.77 to -0.09%) per IQR, respectively, for FVC, and similarly for FEV. Minor allele carrier status for two GSTP1 SNPs and the GSTT1 null genotype were associated with decreases in % predicted lung function. Three SP-A SNPs showed effect modification with exposure to PM from industry and marine traffic.

Conclusions: PM exposure, specifically traffic related, was associated with FVC and FEV reductions and not modified by genotype. Genetic effect modification was suggested for industry and marine traffic PM.