Effects of the Sumatran forest fires (haze) on cognitive function in Indonesian children

Abstract

Background: Smoke from the seasonal forest fires that occur on the Indonesian islands of Sumatra and Kalimantan (often referred to as ‘haze’ in South-East Asia) can reach hazardous levels for extended periods of time. This poses severe health risks to tens of millions of people. We aimed to determine if living in a haze affected province is associated with cognitive function in Indonesian children.Methods: We used data from the Indonesian Family and Life Survey (IFLS) that assessed cognitive function by the Ravens Colored Progressive Matrices (RCPM). Spatially resolved levels of particulate matter less than 2.5 microns in diameter (PM2.5) throughout Indonesia were downloaded from the Atmospheric Composition Analysis Group. We used multilevel mixed linear regression models to estimate associations between haze and annual mean PM2.5 concentrations and cognitive function.Results: There were no differences in RCPM scores for children living in haze provinces compared to children living in non-haze provinces in adjusted models (mean difference=-1.16%, 95%CI=-2.53%, 0.21%) in each survey wave. For children who completed cognitive tests in two successive survey waves, scores on the second RCPM were lower for children who had lived in a haze province all their lives compared to those children who had lived in a non-haze province all their lives (β=-1.50%; 95%CI:-2.94%, -0.07%).Conclusions: Living in a haze province for a prolonged period of time negatively impacted childhood cognitive scores after adjusting for individual factors. These findings may also be relevant for (mainly) women and young children exposed to high levels of household air pollution.