Is there anywhere in the world where people breathe healthy, pollution-free air? This seems doubtful, according to the World Health Organization, which estimates that 99 percent of the global population "breathe air that exceeds WHO guideline limits and contains high levels of pollutants"
Breathing polluted air could affect mental health, and by extension increase the risk of death from cardiovascular disease, according to a new study involving more than 300 million people living in the USA.