Interaction between meteorological factors and air pollutants on the cerebrovascular diseases admissions in Lanzhou City: A time-series study

Abstract

To explore the exposure-lag-response relationships and the interaction effects of meteorological and air pollutants on cerebrovascular disease admissions (CDA), this study used a distributed lag nonlinear model of time series. Univariate analysis showed a “U” shaped between relative humidity (RH) and CDA, daily mean temperature (DMT) and CDA showed fluctuating variations. Except O₃, the relative risk (RR) between air pollutants and CDA showed a monotonically increasing trend. The RR values were maximum at the highest air pollutant concentration, which were RR(NO₂) =2.86(95 %CI:1.79–2.58), RR(PM_2.5) = 1.82 (95 %CI:1.13–2.94), RR(PM₁₀) = 2.94(95 %CI:1.33–6.52), RR(SO₂) = 2.16(95 %CI:1.24–3.75), RR(CO) = 1.91(95 %CI: 1.19–3.06). The interaction results showed statistically significant relative excess risk of interactions (RERI) except DMT with CO and O₃, and RH with PM_2.5 and NO₂. The RERI of DMT with PM_2.5, PM₁₀, and NO₂ on CDA were all greater than 0, with RERI of 0.99 (95 %CI:0.08–1.90), 0.25 (95 %CI:0.03–0.47), and 1.51 (95 %CI:0.49–2.55), respectively, whereas the RERI of DMT with SO₂ on CDA were less than 0. The RERI of RH with PM₁₀ and O₃ on CDA were greater than 0 and were 1.08 (95 %CI:0.03–1.97), 2.32 (95 %CI:0.19–5.51), respectively. All factors except O₃ had cumulative risks on the CDA and there was an interaction between meteorological factors and air pollutants on CDA.