Pollution par les particules atmosphériques fines et ultrafines et risque cardiovasculaire

Humans breathe around 15 m3 of air daily. Urban air contains several pollutants including solid particulate matter (PM). This review will focus on the deleterious effects of PM resulting from human activity on cardiovascular system. The toxicity of PM is linked to their chemical composition that includes heavy metals and organic pollutants and also to their size (fine PM10 and ultrafine PM2,5), as the finest offer a very highly reactive external surface in contact to biological tissue. Theses PM infiltrate deeply the pulmonary system, where they trigger in alveoli an immuno-inflammatory reaction associated to an oxidative burst. These events may aggravate an underlining respiratory pathology and also perturb the alveolar epithelial permeability, which may favour the passage into the circulation of pro-inflammatory mediators and likely also the ultrafine PM that would be then distributed into the cardiovascular system. Numerous epidemiological studies in large cites of USA and Europe consistently demonstrate the link between PM levels and hospital admissions or premature death of cardiovascular origins, whether subjects were exposed for short, medium or long time to PM. PM alter the electrical and autonomic activities of heart, the haemostasis, perturb the vasoreactivity and increase vascular inflammation, which accelerates the progression of atherosclerosis and plaque rupture. These effects are likely potentialized by the metabolic state of subjects (diabetes, obesity). The cellular mechanisms involve an oxidative burst and the activation of pro-inflammatory and apoptotic signalling pathways regulating gene expression. In conclusion, based on the present scientific and medical knowledge, it is established that PM contribute to accelerate and aggravate underlining cardiovascular pathologies leading to premature hospitalization or death of cardiovascular origins, although it is premature to advance that PM initiate these pathologies. Drastic politics aimed to reduce PM emission in each field concerned (industry, transports, agriculture, waste incineration, heating…) is urgently needed to limit health impact of PM which annually are responsible of 3 millions of premature deaths worldwide.