The World Health Organization (WHO) on Tuesday disclosed that 2 million people from more than 1,000 cities across 91 countries die each year because of the effects of massive air pollution.

This type of pollution, which is common in urban hubs, is among the primary causes of heart ailments, lung diseases, asthma and acute lower respiratory sicknesses that often prove to be fatal.

In the UK for instance, air pollution caused by vehicles and power stations has reduced life expectancy by an average of 6 months.

The Xinhua News Agency reported that in almost all countries worldwide, the major contributors to pollution in urban centers are motor vehicles, manufacturing plants, industrial centers, burning of biomass and coal fuels and coal-fired power plants.

The WHO, in its report, said that for rural areas, the burning of coal and wood for houses during cold months is the primary cause of air pollution.

On the other hand, the American Lung Association declared that "air pollution presents a threat to approximately 150 million citizens which is more than half of the entire population of the U.S.

The report also indicated that almost 50 percent of Americans reside in areas where ozone content was found to be excessive while 20 percent live in places that full of short-term points in pollution. Around 6 percent are located in towns and counties that are affected by unsafe particles all throughout the year.

The state of California is considered the most polluted state because of places like Los Angeles, Long Beach, Riverside, Fresno and Bakersfield.

Pollution plays a part in low birth weights, diabetes, cardiovascular disease, heart attack, stroke and shorter life cycles.