Outdoor air pollutants and cardiovascular diseases in Lebanon

Outdoor air pollution is increasingly considered as a serious risk factor for cardiovascular diseases (CVD). High levels of airborne particulate matter (PM) constitute the greatest international air pollution threat. The purpose of this thesis is to broaden our knowledge regarding the relationship between outdoor air pollution and cardiovascular diseases in the Middle Eastern countries, specifically in Lebanon. Moreover, we aimed to develop a scale as CVD screening tool among the Lebanese population. To achieve these goals, we conducted three studies. The first was a systematic review of the literature aiming to assess levels and sources of PM across the Middle East area and to search for an evidence of relationship between PM exposure and CVD (Paper I).The second manuscript was a multicenter case-control study investigating the association between outdoor pollutants and cardiovascular diseases among Lebanese adults (Paper II) while the third study was conducted to develop a score that can be used as a screening tool in clinical and epidemiological settings among the Lebanese adults (Paper III).The annual average values of PM pollutants in the Middle East region are considered to be much higher than the WHO 2006 tolerated levels (PM2.5 = 10 µg/m3, PM10 = 20 µg/m3). We uncovered evidence of an association between PM and CVD in 4 Middle East countries: Iran, Kingdom of Saudi Arabia, Qatar and the United Arab Emirates. Ambient PM pollution is considered a potential risk factor for platelet activation and atherosclerosis. Moreover, it was associated with CVD and found to be linked with an increased risk for mortality and hospital admissions (Paper I). Increased risk of CVD with an odds ratio OR of 5.04, 95% CI (4.44-12.85) for living near busy highway and 4.76, 95% CI (2.07-10.91) for living close to local diesel generator was noticed among population exposed to outdoor air pollution (Paper II). In addition, our results highlight the importance of scale generation, which includes air pollution as predictive factor, as screening tool for patients at risk of CVD. This scale can foresee the cardiovascular disease outcomes better than the established score which use the traditional CVD risk factors (Paper III).In conclusion this study brings new evidence regarding the effects of particulate matter on cardiac diseases, points out the harmful role of diesel exhaust on health and suggest a an important role of traffic exhaust particles in exacerbating heart diseases in the Middle East Region. The developed scale could detect persons at high risk for CVD in the clinical and epidemiological settings. In addition, it serves as an essential public health screening tool for the primary prevention of CVD.Doctorat en Santé Publique