Air pollution has become a central public health issue following a series of environmental calamities, which occurred in Europe during the second half of the XXth century and had an enormous impact on peoples' health and mortality. Since then, abundant scientific evidence has reported on the specific health effects determined by exposure to environmental air pollutants, notably ozone and particulate matter. More recently, worldwide large population-based cohort studies showed positive associations between levels of exposure to common air pollutants and systemic illnesses irrespective of age. Reports in children exposed to airborne hazards showed decreased lung growth and function, increased rates of respiratory allergies and early onsets of asthma, and aggravation of respiratory symptoms and asthma. In adults, the available evidence reports on the increased incidence of acute and chronic respiratory diseases, and also on the early cardiovascular morbidity risk factors, such as arteriosclerosis, thrombosis, decreased heart-rated variability, which may further lead to myocardial infarction and stroke. As a consequence, increased utilization of medical care, outpatient visits to emergency rooms and hospitalizations with a significant impact on individuals' health-related quality of life and costs have been shown. Individual susceptibility to environmental pollutants is an important determinant of the health effects. A number of personal conditions have been associated with the detrimental effects of air pollutants, including sex, nutrition, associated comorbidities, tobacco smoke, occupational exposure and genetic predisposition. In the last years, new policy regulation measures to reduce fine particle emissions and limit involuntary exposure to tobacco smoke proved beneficial, notably in susceptible persons. The present work aimed to 1) provide an overview of the consistent literature on the effects of outdoor and indoor air pollution on human's health, and 2) examine the evidence on the individual's factors of susceptibility to environmental air pollutants, further focusing on three articles from the author addressing the effects of passive smoking in susceptible individuals.