Beware! We are Skating on a Thin Ice: Air Pollution is a Killer.

Air pollution has rapidly emerged as a major environmental hazard in recent times, with potentially catastrophic ramifications for human health.1,2 It has the ability to severely and adversely impact multiple body systems, including the central nervous system (CNS), cardiovascular, dermatological, respiratory, ophthalmologic, and gastrointestinal health. It is a global public health hazard, being responsible for an estimated 6.7 million deaths worldwide in 2016. The World Health Organization (WHO) estimates that between 3.2 to 4.8 million persons succumb yearly because of outdoor and indoor air pollution, respectively. Nearly 90% of people worldwide live in regions where mean air pollution levels exceed acceptable ranges established by WHO.3 Air pollution is caused by several components in the air, which include particulate matter (PM), organic compounds such as polycyclic aromatic hydrocarbons (PAH), inorganic compounds, gases such as nitrogen oxides (NOx), and sulfur dioxide (SO2). PM, in turn, is further classified based on the aerodynamic diameter of the particles: coarse particles are defined as those with a diameter between 2.5 and 10 µm (PM10), fine particles are those with a diameter <2.5 µm but above 100 nm (PM2.5) and ultrafine particles are those with diameter below 100 nm (ultrafine PM). Larger particles (PM10) are more common in industrial emissions, and smaller particles in automobile emissions. Data continues to accumulate on the adverse consequences of air pollution on brain health, with pathogenetic contributions  to the development of dementia, headache, stroke, demyelinating conditions, and psychiatric disorders.