Effects of air pollutants exposure on frailty risk: A systematic review and meta-analysis

Air pollutants have been investigated to be associated with many health issues. Recently, increasing epidemiological studies have suggested the association between air pollution exposure and risk of frailty with inconsistent findings. This systematic review and meta-analysis was to summarize and evaluate effects of exposure to various air pollutants on risk of frailty. PubMed, Embase, Scopus and Web of Science were systematically searched for relevant studies published before May 11, 2024. Studies that explored the potential relationship between exposure to air pollutants (PM_2.5, PM₁₀, O₃, NO_x, solid fuel, secondhand tobacco, and air quality) and risk of frailty were included. The quality of cross-sectional and cohort studies was evaluated using an eight-item assessment instrument for epidemiological studies and Newcastle-Ottawa Scale, respectively. A total of 9,929 papers were retrieved, of which 20 met the inclusion criteria. Meta-analysis indicated that PM_2.5 exposure was significantly associated with frailty assessed by the frailty index [OR (95% CI): 1.24 (1,11-1.38) per 10 μg/m³ increment]. Moreover, solid fuel exposures were significantly associated with an increased risk of frailty assessed by the frailty phenotype [OR (95% CI): 1.91 (1.09-3.34)] or the frailty index [OR (95% CI): 1.25 (1.11-1.41)]. Exposure to PM_2.5 and solid fuel increases the risk of frailty. Environmental protection policies and public health measures should be developed to reduce PM_2.5 concentrations. Effective measures, such as improving stoves and using clean fuels, should be taken to reduce indoor air pollution levels.