A recent study found that approximately 3.3 million deaths are accounted for air pollution every year across the globe. And in 2050, the number can increase twofold.

Several studies have already warned the detrimental effects of air pollution in human health. Ozone, toxins, and other particles have been linked to cardiovascular and lung problems.

Lead author of the study Jos Lelieveld said that "strokes and heart attacks are responsible for nearly 75 percent of air pollution-related mortality. A little over 25 percent is related to respiratory disease and lung cancer."

In developing countries, mostly children below five years old are affected; while in the West, adults 30 years old and above are distressed. In fact, death toll due to outdoor air pollution is higher compared with malaria and HIV cases added together.

Based on statistics, nearly three-quarters of the percentage occur in Asia with almost 1.4 million people dying annually in China and over half a million in India. It is "approximately an order of magnitude higher than that attributable to Chinese road transport injuries and HIV/AIDS, and ranks among the top causes of death," Lelieveld said.

It has been found that fires from coal and wood, used for heating and cooking in China, can be "an inefficient form of fuel combustion that causes a lot of smoke," Lelieveld said. This alone already accounts for nearly one-third of premature deaths in Asia.

On the other hand, approximately 55,000 are killed in the USA and more than twice as much in the European Union (180,000).

Other reasons pinpointed include lack of air monitoring, inability to determine level of toxicity of "fine particulate matter," rapid urbanization, agricultural practice of combining ammonia and animal waste, chemicals from power plants, and pollution from car exhaust in the USA and other regions.

The result was calculated by fusing models of global atmospheric quality with data from satellites and ground-based networks of sensor, together with population data, health statistics, and some research from experts.

"Overall outdoor air pollution... leads to 3.3 million premature deaths per year worldwide," Lelieveld, the atmospheric scientist at the Max Planck Institute for Chemistry in Germany, told Live Science.  "Our study shows that it is particularly important to reduce pollution emissions from residential energy use in Asia. By reducing agricultural emissions, air quality would also improve."