Outdoor and indoor air quality and cognitive ability in young children

Highlights: • Outdoor and indoor air quality and cognitive ability in early childhood is explored. • Long-term but not short-term effects of outdoor NO₂ on verbal ability at age 3 found. • Exposure to indoor damp or condensation predicted lower cognitive ability at age 3. • Secondhand smoke exposure associated with lower cognitive ability at age 3. This study examined outdoor and indoor air quality at ages 9 months and 3 years and their association with cognitive ability at age 3 in England and Wales.