There are more than a billion smokers globally, and one in 25 undergo major surgery each year, according to the W.H.O. In wealthier countries, as many as 16 percent of post-surgical patients develop severe complications; in the developing world, the post-surgery mortality rate can reach 10 percent depending on the country.

Studies have found that smokers who undergo surgery have more than double the rate of complications compared to nonsmokers, posing a significant burden on hospitals around the world. “Not only is it bad for the patient, but it’s bad for the distribution of health services because smokers are likely to be readmitted to the hospital, which potentially denies treatment to someone else,” Professor D’Espaignet said.

The authors of the report said the findings provided a powerful case for doctors to delay elective surgery for smokers to give them more time to quit. They found that patients who stopped smoking a month before surgery had fewer complications six weeks later, and that every tobacco-free week beyond those four weeks improved health outcomes by 19 percent.

The dangers of tobacco are widely understood, but few people appreciate the disadvantages that smokers face when recovering from a hip replacement, open-heart surgery or even a face lift. Smoking adversely affects cardiovascular function and the ability of tissues to heal. That’s because the carbon monoxide in cigarette smoke reduces the oxygen needed for normal cell function. Nicotine is also thought to stymie the clumping of the blood platelets that aid healing.

“Surgery itself is an assault on the body and your recovery is going to be that much harder if you smoke,” said Dr. Kerstin Schotte, a medical officer at the W.H.O. who works on tobacco control and helped write the report.