Table 1 Population-based studies of the effects of air pollution in childhood

Nordling et al. [12]

2007

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.

Exposure to traffic pollution in early childhood is associated with an excess risk of persistent wheezing and sensitisation to inhaled allergens at the age of four years.

Brauer et al. [13]

2008

The development of asthmatic/allergic symptoms and respiratory infections during the first 4 yrs of life was assessed in a birth cohort study (n = approximately 4,000). Outdoor concentrations of traffic-related air pollutants were assigned to birthplace home addresses with a land-use regression model. They were linked by logistic regression to questionnaire data on doctor-diagnosed asthma, bronchitis, influenza and eczema and to self-reported wheeze, dry night-time cough, ear/nose/throat infections and skin rash.

Air pollution exposure in early childhood is associated with sensitisation to food allergens and respiratory symptoms at the age of four years.

Gehring et al. [14]

2009

Annual questionnaire reports of asthma, hay fever, and related symptoms during the first 8 years of life were analyzed for 3,863 children. At age 8, measurements of allergic sensitization and bronchial hyperresponsiveness were performed for subpopulations (n = 1,700 and 936, respectively). Individual exposures to NO₂, PM2.5, and soot at the birth address were estimated by land-use regression models. Associations between exposure to traffic-related air pollution and repeated measures of health outcomes were assessed by repeated-measures logistic regression analysis.

Exposure to traffic-related air pollution seems to cause asthma in children monitored from birth to eight years of age.

Gruzieva et al. [15]

2013

The Swedish birth cohort BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiological Survey) includes 4,089 children who were followed up with repeated questionnaires and blood samples for up to 12 years of age. Residential, daycare, and school addresses, time-activity patterns, emission databases, and dispersion models were used to estimate individual exposure to PM10 and NOx from traffic.

There is a moderate positive association between exposure to traffic-related air pollution in infancy and asthma in children aged up to 12 years, which is possibly stronger in the case of non-allergic asthma.