Beginning in the late 1990s, air pollution declined in New York City following the implementation of clean air and climate policies. According to new research by scientists at Columbia University Mailman School of Public Health, as prenatal exposures to air pollution declined, subsequent measures of children's cognitive development improved. The findings are published in the journal Environmental Health.
The study is based on data collected on more than 1,000 mother-child pairs enrolled in long-term studies at the Columbia Center for Children's Environmental Health (CCCEH) between 1998 and 2020. It is the first to evaluate the relationship between declining levels of prenatal exposure to air pollutants attributed to the enactment of clean air and climate policies and measures of cognitive development in children sequentially enrolled over a 20-year period.
The researchers used data on prenatal exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), and polycyclic aromatic hydrocarbons (PAHs) from successive longitudinal cohort studies. PM2.5 and NO2 were available in the first two cohorts (1998-2016); PAH were monitored in three cohorts (1998-2020). Children were assessed for cognitive development at ages 1, 2, and 3 using the Bayley Scales of Infant and Toddler Development, which provided Mental Development Index (MDI) scores.
Between 1998 and 2016, annual average PM2.5 and NO2 concentrations at pregnant individuals' residences decreased by 32 percent and 30 percent, respectively. Between 1998 and 2020, the PAH concentration based on prenatal personal monitoring of the women decreased by 60 percent. These changes were largely driven by the implementation of the New York City Clean Fuel Bus Program, Clean Air Taxi legislation, the Clean Heat Program, and the Climate Mobilization Act.
The researchers found a 26 percent increase in MDI scores at age 3 when comparing the first and the latest cohort, concurrent with declining air pollution concentrations. After adjusting for multiple confounding factors (years of maternal education, child sex, gestational age, and presence of a smoker in the household), MDI scores increased significantly as air quality improved. The results add to the Center's prior findings, including significant associations between prenatal PM2.5 exposure and changes in children's brain structure and function, as well as adverse cognitive outcomes measured in young children in the first cohort. Potential mechanisms include neuroinflammatory responses, oxidative damage, and changes in synaptic plasticity or structure.
"This study in over a thousand children enrolled over a twenty-year period provides new evidence that policies to reduce fossil fuel emissions benefit developing brains and strongly supports continued efforts to reduce these emissions," says Frederica Perera, PhD, DrPH, Special Research Scientist and Professor Emerita of Environmental Health Sciences at Columbia Mailman School, CCCEH Founder and Director of Translational Research.
Additional authors include Yuqi Miao, Shuang Wang, Molly Algermissen, and Julie Herbstman (CCCEH Director) at Columbia Mailman School.
Support was provided by the John and Wendy Neu Foundation, the New York Community Trust, and the National Institutes of Health grant OD023290.
The authors declare no competing interests.
