Abstract 12482: Exposure to Greenspace Reduces Blood Pressure and Attenuates the Association With Air Pollution in Tamil Nadu, India

Background: Globally, high systolic blood pressure (SBP) is a major cause for cardiovascular mortality. Air pollution affects SBP and diastolic blood pressure (DBP), but has not been studied in relation to greenness in rapidly urbanizing and polluted areas. Here we assess the association between long-term concentrations of ambient PM 2.5, greenness and blood pressure in the Population study of Urban, Rural, Semi-urban Endovascular disease and Holistic Intervention Study (PURSE-HIS) in Tamil Nadu, India. Methods: The study included 8080 randomly selected participants (mean age 42 years; 58% women). We measured greenness using MODIS satellite derived normalized difference vegetation index (NDVI) at 250 m 2 resolutions. We used modeled estimates of annual average PM 2.5 at 1 km 2 developed for Global Burden of Disease to assign to residences. Brachial SBP and DBP were assessed in the dominant arm and an average of three measurements was used in the analysis. The associations were examined using generalized linear regression models controlling for age, gender, waist circumference, physical activity, sodium intake, smoking, stress, and anxiety. Results: The PM 2.5 exposure estimates ranged from 18μg/m 3 to 35μg/m 3 in the study area. In independent multivariate models IQR increase in PM 2.5 (3.0 μg/m 3 ) was associated with a 5.5 mmHg (95%CI: 4.9, 6.2) change in SBP. Stratification of participants into greenness exposures of high, medium and low, showed markedly higher association of PM 2.5 with SBP when comparing those residing in low greenness areas (5.0 mmHg [95%CI: 3, 6.9]) to those in medium (3.7 mmHg [95%CI: 2.8, 4.6]) and high NDVI areas (1.1 mmHg [95%CI: -0.6, 2.8]). Conclusions: Greenness and PM 2.5 were associated with SBP and DBP independently, with significant modification of this association by greenness. Further studies are required to assess interaction between PM 2.5 and greenness on SBP.