Indoor particulate air pollution from open fires and the cognitive function of older people

Abstract

Exposure to indoor air pollution is known to affect respiratory and cardiovascular health, but little is known about its effects on cognitive function. We measured the concentrations and magnetite content of airborne particulate matter (PM) in the indoor environment arising from burning peat, wood or coal in residential open fires. Highest indoor PM2.5 concentrations (60 µg/m 3 , i.e. 2.4 times the WHO-recommended 24-hour mean) occurred when peat was burned, followed by burning of coal (30 µg/m 3 ) and wood (17 µg/m 3 ). Conversely, highest concentrations of coarser PM (PM10-2.5) were associated with coal burning (20 µg/m 3 ), with lower concentrations emitted during burning of wood (10 µg/m 3 ) and peat (8 µg/m 3 ). The magnetic content of the emitted PM, greatest (for both PM size fractions) when coal was burned, is similar to that of roadside airborne PM. Exposure to PM, and to strongly magnetic airborne PM, can be greater for individuals spending ~5 hours/day indoors with a coal-burning open fire for 6 months/year compared to those commuting via heavily-trafficked roads for 1 hour/day for 12 months/year. Given these high indoor PM and magnetite concentrations, and the reported associations between (outdoor) PM and impaired neurological health, we used individual-level data from The Irish Longitudinal Study on Ageing (TILDA) to examine the association between the usage of open fires and the cognitive function of older people. Using a sample of nearly seven thousand older people, we estimated multi-variate models of the association between cognitive function and open fire usage, in order to account for relevant confounders such as socio-economic status. We found a negative association between open fire usage and cognitive function as measured by widely-used cognitive tests such as word recall and verbal fluency tests. The negative association was largest and statistically strongest among women, a finding explained by the greater exposure of women to open fires in the home because they spent more time at home than men. Our findings were also robust to stratifying the sample between old and young, rich and poor, and urban and rural.

Solid cooking fuel use and cognitive decline among older Mexican adults

“…These findings are consistent with research highlighting the negative associations between ambient air pollution and cognitive function 1‐6,19‐22 and on the effects of indoor air pollution from solid fuel use on cognitive health 11,15‐18 . Results suggest that exposure to indoor air pollution from solid fuel use may lead to faster decline in Verbal Learning, Visual Scanning, and Verbal Fluency.…”

“…Findings on the lack of a significant relationship between solid fuel use and baseline Verbal Recall in the full sample are consistent with some studies 18,38 but not others. Some previous research suggests open‐fire heating may lead to diminished Verbal Recall among older adults 11 and that prenatal woodsmoke exposure may lead to neurodevelopmental impairment reducing long‐term figure recall of children 14 . Differences in Verbal Recall findings from those of Maher et al (2021) may be attributed to this study focusing on cooking rather than heating fuels.…”

“…Use of solid fuel for cooking or heating was similarly associated with poorer cognitive abilities in China 18 . Open‐fire heating in Ireland was also associated with worse performance in multiple cognitive tasks 11 …”

“…Household air pollution, however, is highly relevant in low‐ and middle‐income countries (LMICs) where many rely on solid fuels for domestic needs such as cooking, heating, and lighting. Such indoor use of solid fuels can expose household residents to high levels of fine particulate matter (PM 2.5 ) 7 and various chemicals (eg, carbon monoxide, polycyclic aromatic hydrocarbons, free radicals, nitrogen and sulfur oxides, mercury, lead, and magnetite) that are harmful to human health 8‐12 . The World Health Organization has estimated that around three billion people worldwide rely on cooking fuels (such as kerosene, wood, and coal) which pollute indoor environments and that nearly four million premature deaths annually can be attributed to use of such fuels 13…”

Airborne magnetic nanoparticles: environmental risk factors for the transmission of SARS-CoV-2

“…In this regard, high oxidative properties of PM have been attributed to the high iron levels in vehicles emissions [8,9]. This adds to the intrinsic redox activity of particles originating from wood burning [10], which probably arises from the presence of magnetite and other co-associated metal-bearing nanoparticles in soot and smoke [11,12,13]. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint…”