Traffic-related air pollution and childhood respiratory symptoms, function and allergies.
BACKGROUND
Urban air pollution can trigger asthma symptoms in children, but there is conflicting evidence on effects of long-term exposure on lung function, onset of airway disease and allergic sensitization.


METHODS
The spatial distribution of nitrogen oxides from traffic (traffic-NOx) and inhalable particulate matter from traffic (traffic-PM10) in the study area was assessed with emission databases and dispersion modeling. Estimated levels were used to assign first-year exposure levels for children in a prospective birth cohort (n = 4089), by linking to geocoded home addresses. Parents in 4 Swedish municipalities provided questionnaire data on symptoms and exposures when the children were 2 months and 1, 2, and 4-year-old. At 4 years, 73% of the children underwent clinical examination including peak expiratory flow and specific IgE measurements.


RESULTS
Exposure to air pollution from traffic during the first year of life was associated with an excess risk of persistent wheezing (odds ratio [OR] for 44 microg/m3 [5th-95th percentile] difference in traffic-NOx = 1.60; 95% confidence interval [CI] = 1.09-2.36). Similar results were found for sensitization (measured as specific IgE) to inhalant allergens, especially pollen (OR for traffic-NOx = 1.67; 95% CI = 1.10-2.53), at the age of 4 years. Traffic-related air pollution exposure during the first year of life was also associated with lower lung function at 4 years of age. Results were similar using traffic-NOx and traffic-PM10 as indicators.


CONCLUSIONS
Exposure to moderate levels of locally emitted air pollution from traffic early in life appears to influence the development of airway disease and sensitization in preschool children.
Nordling
Emma
E
Department of Occupational and Environmental Health, Stockholm County Council, Stockholm, Sweden.
Berglind
Niklas
N
Melén
Erik
E
Emenius
Gunnel
G
Hallberg
Jenny
J
Nyberg
Fredrik
F
Pershagen
Göran
G
Svartengren
Magnus
M
Wickman
Magnus
M
Bellander
Tom
T
D002675:Child, Preschool; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D007073:Immunoglobulin E / Q000032:analysis; D007223:Infant; D008297:Male; D009589:Nitrogen Oxides / Q000009:adverse effects* / Q000032:analysis*; D052638:Particulate Matter / Q000009:adverse effects* / Q000032:analysis; D011446:Prospective Studies; D012044:Regression Analysis; D012129:Respiratory Function Tests; D012140:Respiratory Tract Diseases / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D001335:Vehicle Emissions / Q000032:analysis*
D009589:Nitrogen Oxides; D052638:Particulate Matter; D001335:Vehicle Emissions; D007073:Immunoglobulin E