Researchers using a new modeling method found that air pollution caused an estimated 8.8 million extra deaths in 2015 globally, according to a study published in European Heart Journal. The number is more than double the previous estimate of 4.5 million extra deaths attributed to air pollution.

This estimate is more than the World Health Organization estimate of extra deaths from tobacco smoking, which was 7.2 million in 2015.

The researchers found that air pollution raises the instance of cardiovascular disease, such as heart attacks and stroke, and respiratory diseases.

According to scientists, national governments and international agencies need to respond with urgency to the issue of air pollution, adjusting current limits on levels of air pollution to match the World Health Organization guidelines.

Read more about this study on the deadly effects of air pollution at Science Daily.