A recent study published in JAMA Network Open delves into the effects of early-life exposure to ozone (O3) on the development of asthma and wheezing in children, both independently and in combination with other environmental pollutants.
Asthma is the leading chronic disease among children, with approximately 6.5% of U.S. children diagnosed in 2021. This condition is influenced by environmental factors, including pollutants like fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone. Despite ongoing research, the long-term effects of O3 exposure on asthma progression in children remain underexplored, with existing studies providing mixed results.
The study aims to enhance understanding of how O3 exposure in early childhood, particularly between birth and two years of age, influences asthma and wheezing in later childhood. Given that early-life respiratory development is critical, the researchers sought to determine whether early O3 exposure has lasting impacts on children’s health.
Study Overview
Researchers hypothesized that higher exposure to ambient ozone, either alone or in combination with other pollutants, would increase the likelihood of asthma and wheezing in children across various age groups. To test this, they examined O3 exposure during the first two years of life and its association with asthma and wheezing between the ages of four and six, with follow-up assessments up to nine years of age.
Participants were drawn from three pediatric cohorts within the Environmental Influences on Child Health Outcomes (ECHO) and Early Childhood Pathways to Health Consortium (ECHO-PATHWAYS). These children were tracked for respiratory health data at multiple intervals, ensuring comprehensive analysis. Preterm births were excluded from the study.
Ozone exposure was measured using a spatiotemporal model, which considered geographic factors and pollutant concentrations. Multipollutant models also analyzed the combined effects of NO2 and PM2.5 exposure. Asthma and wheezing data were collected through caregiver surveys, and statistical analyses, including logistic regression, were used to assess the risk of developing asthma and wheezing.
Key Findings
The study included 1,188 participants, with a mean age of 4.6 years at the four-to-six-year assessment. At this stage, 12.3% of children had asthma, and 15.8% experienced wheezing. By the age of 8.9 years, 9.4% had developed persistent asthma. The cohort’s respiratory health was categorized into four groups: never wheezers, early wheezers, late wheezers, and persistent wheezers.
The mean ambient O3 concentration during early life was 26.1 parts per billion (ppb), with additional exposure to 8.8 ppb of NO2 and 9.3 micrograms per cubic meter (μg/m3) of PM2.5. Primary analysis revealed that a two ppb increase in O3 exposure during early life was associated with a 31% higher likelihood of developing current asthma and a 30% higher likelihood of current wheezing by age four to six.
In secondary models adjusting for additional covariates, the odds ratios remained significant, showing a 26% increased risk for asthma and a 27% increased risk for wheezing. When combined with other pollutants like NO2 and PM2.5, O3 exposure was linked to an elevated risk of asthma, but not significantly linked to the development of current wheezing. Interestingly, interactions between O3 and NO2 showed consistent associations with asthma risk, particularly at higher concentrations of NO2.
Conclusion
The study strengthens the evidence that early-life exposure to ozone is a significant environmental risk factor for the development of asthma and wheezing in children. While ozone exposure alone and in combination with other pollutants like NO2 and PM2.5 can increase the likelihood of these respiratory conditions, the findings underscore the importance of addressing air quality in pediatric health strategies, particularly in the critical early years of development.
These results highlight the need for continued research to refine preventative measures and treatments aimed at reducing asthma and wheezing in vulnerable populations, with a focus on early environmental exposures.
Related topics:
Study Reveals Twins Start Smaller in Pregnancy Than Previously Known
Genetic Link Between Sedentary Behavior and Cardiovascular Risk
Childhood Trauma in Mothers Affects Kids’ Neurodevelopment
