The association of lower respiratory tract illnesses (LRIs) with diesel traffic related air pollutants (D–TRAP) was stronger in children of younger mothers, who were also more likely to have transient-early wheezing with increasing D-TRAP exposure, according to a study led by researchers at the University of Arizona Mel and Enid Zuckerman College of Public Health and the Arizona Respiratory Center.
[Photo: Dr. Paloma Beamer]
The research team used data from the Tucson Children’s Respiratory Study, a longitudinal birth cohort designed to investigate risk factors for LRIs in early childhood and chronic lung disorders later in life. Of the original 1246 children enrolled, 825 had enrolment addresses from which D-TRAP exposure could be estimated and were followed by study physicians for the first 3 years of life: 23.3% had one wheezing LRI; 8.5% had two; and 6.1% had three to five.
Each log increase of D-TRAP exposure was associated with an increased incidence rate ratio for wheezing LRIs. Children of mothers <21 or 21–25 years old had a significantly higher incidence rate ratio per log increase of D-TRAP exposure. D-TRAP exposure was associated with transient wheezing among children with mothers <21 years old and 21–25 years old, but not among children with older mothers for 26–30 years old and OR for >30 years old. Late-onset and persistent wheezing phenotypes were not associated with D-TRAP exposure.
“To our knowledge, this is the first study demonstrating that younger maternal age modifies the effect of air pollution on children’s respiratory outcomes,” said lead author Dr. Paloma Beamer, associate professor at the UA Zuckerman College of Public Health and associate scientist with the Arizona Respiratory Center.
Factors directly or indirectly related to maternal age such as biological factors associated with lung growth may make their infants more susceptible to wheeze with increased D-TRAP exposure. Younger mothers are at increased risk of preterm delivery, with lower birth weight or small for gestational age babies, independent of socioeconomic status, all of which are risk factors for reduced lung function later in life, although that did not account for the relationships reported here.
The study, “Increased wheezing risk with diesel exposure among children of younger mothers,” was published in the European Respiratory Journal, September 2015. The article may be accessed at the following link: http://erj.ersjournals.com/content/46/3/853