The causal relationship between exposure to urban air pollution and morbidity and mortality has now been established by numerous epidemiological studies. There are two types of health effects associated with air pollution (AP): short-term effects and long-term effects. The former include clinical, functional, or biological manifestations occurring a few days or weeks following daily fluctuations in ambient AP levels, which can lead to an increase in the number of hospitalizations or emergency room visits for respiratory and cardiovascular causes. Long-term effects, on the other hand, occur after several months or years of exposure to AP, which can lead to deaths, particularly from cardiovascular causes as well as lung cancer, linked to fine particles with a diameter of less than 2.5 µm (PM2.5). Exposure to air pollution can also cause other, milder health issues (coughing, allergies, asthma attacks, irritation, etc.) that affect a significant portion of the population. (R.A.)