Objective To investigate the long-term effect of fine particulate matter (PM2.5) components of black carbon, ammonium, sulfate, nitrate and organic matter on body mass index (BMI).
Methods A total of 4 717 middle-aged and elderly individuals, aged no less than 45 years, were selected from China Health and Retirement Longitudinal Study database in 2011 and 2015. Bayesian kernel machine regression was performed to investigate the individual effects, interactions, and combined effects of black carbon, ammonium, sulfate, nitrate and organic matter on BMI.
Results The result showed that sulfate, black carbon and ammonium had a posterior inclusion probability(PIP) of 0.99, 0.94, and 0.80, respectively, suggesting that all three components were significantly associated with BMI. When the other four components were fixed at the 25th, 50th, and 75th percentiles, for every IQR increase in black carbon, BMI was increased by 1.15 (95%CI: -0.03, 2.33), 1.45 (95%CI: 0.41, 2.49), and 1.61 (95%CI: 0.47, 2.75)kg/m2, respectively. When the other four components were fixed at the 25th, 50th, and 75th percentiles, for every IQR increase in ammonium, BMI was increased by 1.12 (95%CI: -0.50, 2.74), 1.33 (95%CI: -0.16, 2.82), and 1.51 (95%CI: 0.003, 3.02)kg/m2, respectively. When the other four components were fixed at the 25th, 50th, and 75th percentiles, BMI was negatively correlated with every IQR increase in sulfate, with specific effect values of -2.66 (95%CI: -4.07, -1.25), -2.59 (95%CI: -3.84, -1.34), and -2.36 (95%CI: -3.78, -0.94)kg/m2, respectively. The result of combined effect showed that the combined exposure to mixed PM2.5 components was positively correlated with overall BMI.
Conclusion Exposure to black carbon or ammonium alone may increase BMI level in middle-aged and elderly people in China, and combined exposure to PM2.5 components is also positively correlated with BMI. Therefore, it is necessary to strengthen the prevention and control of PM2.5 exposure, especially exposure to black carbon and ammonium.
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