New York air pollution fell over two decades, while toddlers' mental development scores rose 26%, study finds
For more than two decades, Professor Frederica Perera and a team from the Columbia Center for Children's Environmental Health tracked pregnant women's air pollution exposure and their children's development in disadvantaged communities of Northern Manhattan and the South Bronx. More than 1,100 children were assessed at ages one, two and three. Published in the journal Environmental Health, the study ‘Less air pollution previously related to clean air and climate policies is linked to improved cognitive scores over time in NYC children’ found that as New York's air quality improved, toddlers' mental development scores rose alongside it. Here's how the two-decade study unfolded, and what the researchers found.
Tracking more than two decades of air pollution and toddler development in New York
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 between 1998 and 2020, using data on prenatal exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), and polycyclic aromatic hydrocarbons (PAHs) from successive cohorts. Children were assessed for cognitive development at ages one, two and three using the Bayley Scales of Infant and Toddler Development, which produced Mental Development Index (MDI) scores. Perera, the study's founder and lead researcher, told The Guardian, "In the early years of the study, we reported significant associations between prenatal exposure to air pollution and neurodevelopment effects in the children. That was bad news."
How NYC's air got cleaner, and how much toddlers' scores improved
Between 1998 and 2016, annual average PM2.5 and NO2 concentrations at pregnant women's residences fell by 32% and 30%, respectively, while PAH concentrations dropped by 60% between 1998 and 2020, changes largely driven by the New York City Clean Fuel Bus Program, Clean Air Taxi legislation, the Clean Heat Program and the Climate Mobilization Act. According to the Columbia Mailman press release, comparing the earliest and most recent cohorts, researchers found a 26% increase in MDI scores at age three, concurrent with declining pollution levels across the same period.
Ruling out other explanations: Smoking and maternal education
To make sure air quality itself was really driving the results, and not something else going on at the same time, the researchers controlled for other factors that could affect a child's development, how much schooling the mother had, whether the child was a boy or girl, how far along the pregnancy was at birth, and whether anyone in the household smoked. Even after accounting for all of that, kids' scores still rose as the air got cleaner. This fits with what the Center had already found in earlier work, that pollution exposure before birth can actually change how a child's brain develops and functions. The researchers think a few things could be behind this, inflammation in the brain, damage from oxidative stress, and changes to how brain cells connect and communicate with each other.
What the researcher says the findings mean for policy
Reflecting on the study's significance, Perera said, "This study in over a thousand children enrolled over 20 years provides new evidence that policies to reduce fossil fuel emissions benefit developing brains and strongly supports continued efforts to reduce these emissions." The research adds to a growing body of evidence connecting clean air and climate policy to measurable improvements in child health outcomes, reinforcing the case for continued investment in reducing fossil fuel emissions in cities.
Tracking more than two decades of air pollution and toddler development in New York
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 between 1998 and 2020, using data on prenatal exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), and polycyclic aromatic hydrocarbons (PAHs) from successive cohorts. Children were assessed for cognitive development at ages one, two and three using the Bayley Scales of Infant and Toddler Development, which produced Mental Development Index (MDI) scores. Perera, the study's founder and lead researcher, told The Guardian, "In the early years of the study, we reported significant associations between prenatal exposure to air pollution and neurodevelopment effects in the children. That was bad news."
How NYC's air got cleaner, and how much toddlers' scores improved
Between 1998 and 2016, annual average PM2.5 and NO2 concentrations at pregnant women's residences fell by 32% and 30%, respectively, while PAH concentrations dropped by 60% between 1998 and 2020, changes largely driven by the New York City Clean Fuel Bus Program, Clean Air Taxi legislation, the Clean Heat Program and the Climate Mobilization Act. According to the Columbia Mailman press release, comparing the earliest and most recent cohorts, researchers found a 26% increase in MDI scores at age three, concurrent with declining pollution levels across the same period.
Ruling out other explanations: Smoking and maternal education
To make sure air quality itself was really driving the results, and not something else going on at the same time, the researchers controlled for other factors that could affect a child's development, how much schooling the mother had, whether the child was a boy or girl, how far along the pregnancy was at birth, and whether anyone in the household smoked. Even after accounting for all of that, kids' scores still rose as the air got cleaner. This fits with what the Center had already found in earlier work, that pollution exposure before birth can actually change how a child's brain develops and functions. The researchers think a few things could be behind this, inflammation in the brain, damage from oxidative stress, and changes to how brain cells connect and communicate with each other.
What the researcher says the findings mean for policy
Reflecting on the study's significance, Perera said, "This study in over a thousand children enrolled over 20 years provides new evidence that policies to reduce fossil fuel emissions benefit developing brains and strongly supports continued efforts to reduce these emissions." The research adds to a growing body of evidence connecting clean air and climate policy to measurable improvements in child health outcomes, reinforcing the case for continued investment in reducing fossil fuel emissions in cities.
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