Ever wonder how the tobacco industry has survived a decades-long campaign by public health advocates and government to stamp out the nation’s deadliest habit? One word: addiction.

Now, thanks to a U.S. Surgeon General’s report released this month, the public can find out a lot more about how potent cigarette addiction really is and how it has changed over the years.

“Cigarettes today deliver more nicotine and deliver it quicker than ever before,” says a consumer pamphlet issued with the report. This change is especially dangerous to adolescents, whose bodies are more sensitive to nicotine and who are more easily addicted than adults — which may explain why the industry picks up about 1,000 new teen smokers a day. And why the vast majority of smokers pick up the habit by the time they’re 19.

None of this is an accident: “The additives and chemicals that tobacco companies put in cigarettes may have helped make them more addictive,” says the pamphlet.

Nobody knows exactly when these changes occurred because the public isn’t privy to the industry’s methods. But the 700-page report for the first time pulls together decades of research, and some internal industry documents, to paint a picture of how the content and design of cigarettes have changed over the years.

The chemical form of nicotine has been altered so it is delivered to the brain more rapidly and effectively, setting off the craving for more. This “free nicotine” would make the inhaled smoke harsher, perhaps discouraging smokers, especially new ones. But the industry has found ways to modify that effect.

Filter holes and other types of ventilation make it easier to inhale more deeply. Sugar and moisture enhancers reduce the burning sensation, making smoking seem smoother. Even a change in the size of microscopic particles in smoke impacts how effectively nicotine is delivered, which can intensify the quick buzz that smokers want.

Suffice it to say, this is not your father’s cigarette.

The report couldn’t have come at a better time. The dramatic, nearly decade-long decline in teen smoking has halted among younger teens, and there’s evidence that more of them may be taking up the habit, according to the University of Michigan’s latest survey in high schools. Smoking among 10th-graders, which peaked in 1996 at 30.4%, had dropped by 2008 to 12.3%. Since then, it has begun to rise slightly, this year to 13.6%.

It’s devastating to see more teenagers take up smoking despite years of public smoking bans, ad campaigns aimed at them and tobacco tax hikes that make cigarettes too expensive for some young people.

So what’s to be done?

For starters, states that have squandered the opportunity to effectively use their share of the multibillion-dollar tobacco settlement fund should do so now, directing that money toward programs to protect kids from smoking, help adults quit and prevent deadly diseases. The few states that have used the money productively, such as Maine and Washington, have seen significant progress. But even these states have begun to cut back.

The federal government — with new authority granted by a 2009 law — has other weapons, such as graphic warning labels, and appears to be off to a fast start in proposing them.

If the nation slacks off in the campaign against smoking, a whole new generation will get hooked, and 440,000 Americans will continue to die each year.