Air pollution has caused the death of 8.8 million people in 2015 - almost double the previous estimate of 4.5 million, according to researchers from Germany and Cyprus.
According to the World Health Organization, smoking causes the deaths of 7 million people worldwide every year.
Scientists call for an urgent cessation of the burning of fossil fuels.
In Europe, air pollution has led to the deaths of about 790,000 people, between 40 and 80 percent of whom from cardiovascular diseases such as heart attack and stroke.
Fine dust particles in the air are particularly dangerous to health because they penetrate deep into the lungs and may even pass into the bloodstream.
Dust particles with a diameter less than 2.5 microns are more dangerous than previously thought. They are the main cause of respiratory and cardiovascular diseases.
Scientists recommend lowering the standard in the European Union, which is now 25 micrograms per cubic meter of air, and is 2.5 times higher than recommended by the WHO.
Every year, air pollution causes 120 additional deaths per 100,000 people, and in Europe this increase is up to 200 cases per 100,000 people.
"Smoking can be avoided, but air pollution can not," says another researcher, Professor Thomas Münzel of the Department of Cardiology at the Medical University Center in Mainz, Germany, quoted by bTV.