By Michael Graham Richard, Source: Treehugger

Air quality has been improving over time in many cities. For example, Los Angeles isn’t quite synonymous with smog the way it used to be… But unfortunately, while some places are getting better, more others are getting worse, especially as a larger percentage of humanity is moving to urban areas every year. How big a deal is this? Let’s just say that air pollution now kills more people every year than malaria and AIDS combined and that according to the World Health Organization (WHO), air pollution now the world’s biggest environmental health risk with 7 million deaths per year.

The WHO has created database that contains results of ambient (outdoor) air pollution monitoring from almost 1600 cities in 91 countries. The results are rather alarming.

Read more at: Treehugger