Bill Gates and Mayor Michael R. Bloomberg announced on Wednesday their decision to spend $500 million to raise awareness on the negative effects of smoking.

Mr. Bloomberg’s foundation plans to add $250 million over four years to a program Bloomberg started several years ago. The Bill & Melinda Gates Foundation will invest $125 million over the next four years.

The Gates Foundation has spent more than $2 billion on AIDS programs and about $1.2 billion on malaria. “All the money in the world will never eradicate tobacco,” Mr. Bloomberg said at a joint news conference at TheTimesCenter in Midtown Manhattan. “But this partnership underscores how much the tide is turning against this deadly epidemic.”

The anti-smoking campaign, nicknamed Mpower, coordinates efforts by the Bloomberg Initiative to Reduce Tobacco Use, the World Health Organization, the World Lung Foundation, the Johns Hopkins Bloomberg School of Public Health, the foundation of the Centers for Disease Control and Prevention and the Campaign for Tobacco-Free Kids.

“Together we can make a clear, measurable difference – not just for ourselves and our generation but for the generations that come after us,” Mayor Bloomberg said.

A recent report released by China’s tobacco control office said that China has 15 million (1.5 percent) underage smokers. China and other poor countries where tobacco is a state-owned monopoly should get special attention, Gates said.

Tobacco advertisements are partly to blame for the rising rate of tobacco addiction. “What we have to show them is that the revenue they get, the profits they get from selling cigarettes, are dwarfed by the expense to society,” Bloomberg said.