Indoor air pollution and cognitive health in older adults: a systematic review and meta-analysis

Maintaining cognitive health in older adults is an important public health challenge. We systematically evaluated associations between indoor air pollution (IAP) exposure and global cognitive function, cognitive subdomains, and cognitive impairment-related outcomes in older adults. PubMed, Web of Science, Embase, and the Cochrane Library were searched through February 2026 for observational studies of IAP exposure and cognitive outcomes in older adults. Two reviewers independently screened studies, extracted data, and assessed study quality. Random-effects meta-analyses were conducted where appropriate. Continuous cognitive estimates were harmonized to SD units; global cognitive function was synthesized by exposure assessment category, and cognitive impairment-related outcomes were grouped by clinical outcome type and effect measure. Twenty-one studies involving 249,982 participants were included. Fuel-use proxy exposure was associated with poorer global cognitive function (pooled β = −0.13, 95% CI: −0.16 to − 0.09; I² = 86.9%), as was pollutant concentration-based exposure (pooled β = −0.10, 95% CI: −0.18 to − 0.02; I² = 0%). Cognitive subdomain analyses showed poorer memory performance (k = 7; pooled β = −0.09, 95% CI: −0.11 to − 0.06; I² = 49.1%), executive-attentional function (k = 3; pooled β = −0.24, 95% CI: −0.27 to − 0.20; I² = 15.2%), and mental status (k = 3; pooled β = −0.20, 95% CI: −0.23 to − 0.16; I² = 38.9%); orientation was reported in one study. Fuel-use proxy exposure was also associated with higher hazards of cognitive decline (pooled HR = 1.22, 95% CI: 1.14–1.31) and cognitive impairment or mild cognitive impairment (MCI) (pooled HR = 1.24, 95% CI: 1.11–1.37). Most included studies, including most cohort studies, used fuel-use proxy measures. Egger’s test for the 12-estimate fuel-use proxy global-cognition analysis was not statistically significant ( P = 0.092), and sensitivity analyses supported the direction of the main findings. IAP exposure was associated with poorer global cognitive function, poorer performance across several cognitive subdomains, and higher hazards of cognitive decline and cognitive impairment/MCI. Given the observational nature of the evidence, these findings should not be interpreted as demonstrating causality. Prospective studies with direct or repeated indoor pollutant measurements and repeated cognitive assessments are needed. PROSPERO CRD42024621110. Not applicable.