Associations of greenness and air pollution with leukocyte telomere length in Chinese children and adolescents

Evidence on the associations of greenness and air pollution with telomere length (TL) in children and adolescents remains scarce, and the potential role of air pollution in the greenness-TL association is unclear. We aimed to evaluate the relationships of greenness and air pollution with leukocyte TL (LTL) in children and adolescents and further explore further explore the interaction and mediation of air pollution on the greenness-LTL association. In this cross-sectional study, 1151 children and adolescents aged 6-18 years were recruited from Liuzhou, China. Greenness (measured by the soil-adjusted vegetation index [SAVI], normalized difference vegetation index [NDVI], and enhanced vegetation index [EVI]) and air pollution (PM_2.5, PM₁₀, NO₂, SO₂, and CO) were estimated based on participants' school and home addresses. Multiple linear regression models were employed to assess the associations of greenness and air pollution with LTL. An interquartile range (IQR) increment in SAVI_{500 m} was associated 3.32 % (95 % confidence interval [CI]: 1.17 %, 5.51 %) longer LTL, while an IQR increment in PM_2.5, PM₁₀, NO₂, SO₂, and CO were associated with 2.26 % (95 % CI: -4.32 %, -0.16 %), 5.20 % (95 % CI: -7.48 %, -2.85 %), 9.90 % (95 % CI: -13.33 %, -6.34 %), 7.64 % (95 % CI: -11.21 %, -3.91 %), and 6.61 % (95 % CI: -9.77 %, -3.35 %) shorter LTL, respectively. Interaction and mediation were identified for PM₁₀, SO₂, NO₂, and CO in the greenness-LTL association with mediation proportions from 37.90 % to 68.69 %. In conclusion, greenness exposure was positively associated with leukocyte telomere length in children and adolescents, and this association is primarily mediated by the attenuation of air pollution exposure.