Health editor, BBC News online
Although smoking is becoming less popular in many parts of the world, the total number of smokers is growing, global figures reveal.
In 2012, 967 million people smoked every day compared with 721 million in 1980, data from 187 countries shows.
The rise is linked to population growth, researchers told JAMA.
With the Earth's population having more than doubled in the last 50 years to seven billion, there are simply more people to take up the habit.
Several large countries, including Bangladesh, China and Russia, have seen increasing numbers of inhabitants take up smoking in recent years, the figures show.
Indeed, some of the highest smoking rates are now seen in the developing world, according to the JAMA report from the University of Washington's Institute for Health Metrics and Evaluation (IHME) in the US.
But global smoking prevalence - the proportion of the world's population that smokes - has gone down.
Around three in 10 men (31%) and one in 20 women (6%) now smoke daily compared with four in 10 men (41%) and one in 10 women (10%) in 1980.
In terms of countries with the highest prevalence of tobacco use, East Timor tops the list with 61% of its population smoking every day.
The twin Caribbean islands of Antigua and Barbuda are bottom at 5%.
Certain countries, including Canada, Iceland, Norway and Mexico, have been more successful than most at getting inhabitants to either quit or never take up smoking.
In terms of ill health, the greatest toll is likely to be in countries with both a high prevalence of smoking and a high consumption of cigarettes, say the researchers - namely Greece, Ireland, Italy and Japan as well as China, Kuwait, the Philippines, Russia, Switzerland and Uruguay.
Lead researcher Dr Christopher Murray, who is director of the IHME, said: "Despite the tremendous progress made on tobacco control, much more remains to be done."
The World Health Organization says millions of additional lives could be saved with continued implementation of policies such as increased cigarette taxes and smoke-free air laws.
Amanda Sandford of Action on Smoking and Health (ASH) said: "As the overall number of smokers worldwide is still rising, this study shows how important it is for all countries to implement a range of tobacco control measures to curb the terrible toll of tobacco-related illness and death.
"Low and middle-income countries in particular face an enormous challenge to fend off the powerful tobacco industry and stop smoking rates escalating."
Simon Clark, director of the smokers' group Forest, said: "We support campaigns that educate people about the health risks of smoking.
"However, many tobacco control policies involve excessive restrictions on where people can smoke and the deliberate stigmatisation of millions of consumers worldwide."
He added: "Tobacco is a legal product and consumers should be treated with respect, not vilified or forced to quit through extreme and often illiberal regulation."
Globally, an estimated 6.25 trillion cigarettes were smoked by people during the year 2012 compared with 4.96 trillion in 1980.
