April 25, 2023

expert reaction to study looking at air quality in homes in India and a measure of visual cognition in babies

A study published in eLife looks at air quality in India and visual cognition in the first two years of life.

Dr Saloni Krishnan, Reader in Cognitive Neuroscience, Royal Holloway, University of London, said:

“This study indicates there is an interesting difference in aspects of visual cognition in children with homes in rural India with poor air quality but has not definitively established if air quality caused these changes.

“It is important for parents to note that effects were seen only in specific aspects of the visual measures, not in more general cognitive scales.  The long-term consequences of these experimental differences are not well established.

“This study was an observational study, so further research is necessary to investigate if air quality causes these changes.”

Prof Anna Hansell, Professor of Environmental Epidemiology; Director of the Centre for Environmental Health and Sustainability; and Director of the NIHR Health Protection Research Unit in Environmental Exposures and Health, University of Leicester, said:

“This is an observational study in a high air pollution setting in rural India, with use of biomass fuels such as cow dung for cooking in some households.

“The authors find an association with visual processing scores in year 1 but not year 2 of life and, importantly, do not see an effect with standardised assessments of other aspects of cognition.  This raises the question as to whether this is a true finding, or can be explained by chance or other factors.  If it is a true finding, it’s unclear whether it relates to direct effects on the eye in smoky rooms leading to subsequent impact on visual cognition, rather than on cognitive development itself.  The authors have adjusted for social class, but it’s possible other socio-economic or lifestyle differences such as diet may explain the differences.

“The analyses use an air quality index to indicate degree of air pollution exposure, rather than actual measurement concentrations, which makes it more difficult to directly compare with studies elsewhere.

“This looks to be a carefully conducted study in challenging settings, but does not provide clear-cut conclusions.  We know air pollution can affect childhood development of other parts of the body such as the lungs, so it’s important to continue to investigate the impact of air pollution on children’s cognitive development.”

‘Poor air quality is associated with impaired visual cognition in the first two years of life: a longitudinal investigation’ by John P. Spencer et al. was published in eLife at 00:01 UK time on Tuesday 25 April 2023.

DOI: 10.7554/eLife.83876

Declared interests

Dr Saloni Krishnan: “No conflicts to declare.”

Prof Anna Hansell: “I do not have conflicts of interest to report.

I am Chair of the Committee on the Medical Effects of Air Pollution (COMEAP), but comments here are in a personal capacity as Professor in Environmental Epidemiology at the University of Leicester.”