Lung cancer is what people usually fear from smoking, and yes, that can take years to strike. But Thursday's report says there's no doubt that tobacco smoke begins poisoning immediately - as more than 7,000 chemicals in each puff rapidly spread through the body to cause cellular damage in nearly every organ.
"That one puff on that cigarette could be the one that causes your heart attack," said Surgeon General Regina Benjamin.
Or the one that triggers someone else's: "I advise people to try to avoid being around smoking any way that you can," she said.
About 443,000 Americans die from tobacco-caused illnesses every year. While the smoking rate has dropped dramatically since 1964, when the first surgeon general's report declared tobacco deadly, progress has stalled in the past decade. About 46 million adults - one in five - still smoke, and tens of millions more are regularly exposed to secondhand smoke. The government had hoped to drop the smoking rate to 12 percent by this year, a goal not only missed but that's now been put off to 2020.
Thursday's report is the 30th issued by the nation's surgeons general to warn the public about tobacco's risks.
"How many reports more does Congress need to have to say that cigarettes as a class of products ought to be banned?" asked well-known nicotine expert Dr. K. Michael Cummings of the Roswell Park Cancer Institute, who helped to review the report. "One-third of the patients who are in our hospital are here today because of cigarettes."
Still, this newest report is unusual because it devotes more than 700 pages to detail the biology of how cigarette smoke accomplishes its dirty deeds - including the latest genetic findings to help explain why some people become more addicted than others, and why some smokers develop tobacco-caused disease faster than others.
There is no safe level of exposure to cigarette smoke, whether you deliberately inhale it or are a nonsmoker who breathes in other people's fumes, the report concludes. Nor is there evidence yet to tell if efforts to develop so-called safer cigarettes really will pan out.
But more recently it's become clear that some of the harms - especially those involving the heart - kick in right away, said Dr. Terry Pechacek of the Centers for Disease Control and Prevention.
That means social smoking, the occasional cigarette at a party, can be enough to trigger a heart attack in someone whose arteries already are silently clogged, he said.
"Too often people think the occasional social cigarette is not so dangerous, when in fact this report says yes, it is," he said.
So is breathing secondhand smoke. When Pueblo, Colo., banned smoking in all public places in 2003, the number of people hospitalized for heart disease plummeted 41 percent in just three years, the report found.
Why? Cigarette smoke immediately seeps into the bloodstream and changes its chemistry so that it becomes more sticky, allowing clots to form that can squeeze shut already narrowed arteries, the report explains. That's in addition to the more subtle long-term damage to blood vessels themselves, making them more narrow. And no one knows how little it takes to trigger that clotting.
Kicking the habit lets your body start healing, Benjamin stressed: "It's never too late to quit but the sooner you quit the better. Even if you're 70, 80 years old and you're a smoker, there's still benefit from quitting."