More than 80 percent of people living in urban areas that monitor air pollution are exposed to air quality levels that exceed the World Health Organization (WHO) limits, according to its latest report.
The Environmental Protection Agency (EPA) defines air pollution as “any visible or invisible particle or gas found in the air that is not part of the natural composition of air.” This is a very serious problem—7 million premature deaths annually are linked to air pollution, according to WHO.
Globally, outdoor air pollution has increased by 8 percent from 2011 until 2015. All regions of the world are affected, but populations in low-income cities are the most impacted.
The PM2.5 micro-particles, classed as a Group 1 carcinogen by WHO, are tiny particulate matter that can cause stroke, heart disease, and chronic respiratory diseases. These types of particles are small and fine, making it easier to affect the respiratory system and thus particularly dangerous to health.
The following list includes cities that are either industry hub, popular with tourists or have large populations.