A new study shows that childhood exposure to indoor air pollution may have long-term effects on brain health, with possible cognitive impairment appearing decades later.
People across the globe, especially in low-income countries, continue to use solid fuels like coal, wood and plant waste for cooking and heating. The resulting indoor air pollution exposes children to smoke and particles at key stages of brain development.
"Nearly 30% of the global population, roughly 2.4 billion people, still cook without clean fuels. Our findings indicate that growing up in a smoke-filled household may impair brain health and cognitive abilities throughout life," says University of Helsinki researcher Xu Zong.
, the study is the first to investigate how early-childhood exposure to indoor air pollution affects cognitive performance in adulthood. It analysed nationally representative data from over 7,000 Chinese adults aged 45, using advanced machine learning techniques.
Childhood exposure may accelerate cognitive decline in brain function
Individuals exposed as children to indoor air pollution from solid fuels performed significantly worse on cognitive tests in adulthood.
"The association remained strong in two key areas of cognitive function episodic memory and mental intactness. This indicates that early exposure may accelerate age-related cognitive decline in several areas of brain function," notes Zong.
The study further explored how childhood exposure to indoor air pollution may contribute to poorer cognitive performance in later life, identifying two main pathways: biological and socioeconomic.
Among biological mechanisms, overweight and limitations in daily activities were highlighted, suggesting that early exposure may harm long-term physical health and indirectly impact brain function.
In terms of socioeconomic mechanisms, childhood exposure to air pollution was associated with lower levels of education and income in adulthood, both of which are known risk factors for cognitive decline.
Gender differences significant, with tobacco and alcohol use also prominent
Men, smokers and regular alcohol users were particularly vulnerable to the detrimental effects of early exposure to indoor air pollution on cognitive performance. The results are consistent with the idea that inflammation and stress - often exacerbated by tobacco or alcohol use - may amplify the neurological damage caused by air pollution.
"Our study emphasises that early exposure to air pollution affects later cognitive health through both biological and social pathways," says Zong.
"That is why public health efforts should combine clean energy initiatives with preventive strategies that support lifelong health and positive behaviours."
Towards clean household energy
The results underscore the need for global policies promoting clean household energy, particularly in regions where reliance on solid fuels remains high.
"Switching to cleaner fuels, such as gas or electricity, is not merely an environmental or respiratory health measure . It is also an investment in long-term cognitive wellbeing that could safeguard brain health for future generations," states Zong.
