Smoking rates have fallen globally since the World Health Organisation (WHO) introduced a treaty aimed at reducing tobacco demand, according to a new study.

Countries that followed the treaty’s measures most closely saw greatest reductions in smoking from 2005–2015.

But just 1 in 5 countries that have signed up to the treaty have introduced adequate tax and price increases on tobacco, according to the results published in The Lancet Public Health journal.

The WHO’s Framework Convention on Tobacco Control (FCTC) was adopted in 2003 and came into force in 2005. It included measures and policies aimed at preventing and reducing tobacco use, such as smoking bans, health warnings and education.

Alex Engel, international tobacco control manager at Cancer Research UK, said that despite significant progress in some countries, too many haven’t fully adhered to the treaty.

“It’s alarming that only 1 in 5 countries have implemented adequate tobacco tax and price increases, which are the most effective measure for reducing smoking, especially in low–and middle–income countries,” she said.

“Smoking is the single most preventable cause of death in the world, killing almost 6 million people and causing more than £800 billion in health care costs and lost productivity annually worldwide.”

The research looked at 126 countries, all but 10 of which signed up to the treaty. Smoking rates fell by an average of more than 2.5% in the countries that adopted the framework, a steeper fall than in the other 10 nations.

The researchers looked at how closely countries implemented 5 key policies and the effect this had on smoking rates. The measures were taxation; smoke–free policies; warning labels; bans on advertising, promotion and sponsorship; and programmes to help people quit smoking.

They found that the stringency with which the measures were adopted by a country was linked to the fall in smoking seen there.

Just 1 country had implemented all 5 measures at the level most effective in reducing tobacco use, while 91 countries had only 1 or no measures at this level.

Each additional measure implemented at the highest level accounted for an extra 1% drop in a country’s smoking rate. While smoking rates fell in the majority of countries, there was no change or an increase in smoking rates in around a third.

Dr Geoffrey Fong, one of the study’s authors, acknowledged that while the framework had made remarkable progress, there are still far too many countries where the treaty and its implementation has fallen short.

“One important cause of this is the tobacco industry’s influence, particularly in low– and middle–income countries,” he said.