Ambient Air Pollution Triggers Wheezing Symptoms in Infants

¹ University of Copenhagen, Denmark
² Aarhus University, Denmark
³ Copenhagen University Hospital, Denmark
⁴ Univeristy of Copenhagen, Denmark

^* To whom correspondence should be addressed. E-mail: zorana{at}cancer.dk.

Accepted 16 January 2008

	Abstract

Rationale: There is limited evidence for the role of air pollution in development of wheezing symptoms in young children.

Objectives: To study the impact of exposures to air pollution on wheezing symptoms in children under the age of three and with genetic susceptibility to asthma.

Methods and Measurements: Daily symptoms recordings were obtained for a panel of 205 children participating in the birth cohort study Copenhagen Prospective Study on Asthma in Children and living in Copenhagen in the first three years of life. Daily air pollution levels for particulate matter less than 10 µm in diameter(PM10), number concentration of ultrafine particles, nitrogen dioxide (NO2), nitrogen oxide (NOx), and carbon monoxide (CO) were available from a central background monitoring station in Copenhagen. The association between incident wheezing symptoms and air pollution on the concurrent and previous 4 days were estimated by logistic regression model (generalized estimating equation) controlling for temperature, season, gender, age, exposure to smoking, and paternal history of asthma.

Main Results: We found significant positive associations between concentrations of PM10, NO2, NOx, CO and wheezing symptoms in infants (age 0-1) with 3 to 4 days delay. Only the traffic related gasses, NO2, NOx showed significant effects throughout the three years of life, albeit attenuating after the age of one. Effects of ultrafine particles were comparable to those of NO2 and NOx in the first year of life, although estimated with less certainty due to missing data.

Conclusions: Air pollution related to traffic is significantly associated with wheezing symptoms development in the first three years of life.

Keywords: air pollution, asthma, infants, traffic, wheeze