WASHINGTON » Millions of smokers could be priced out of health insurance because of tobacco penalties in President Barack Obama’s health care law, according to experts who are just now teasing out the potential impact of a little-noted provision in the massive legislation.

The Affordable Care Act — "Obama­care" to its detractors — allows health insurers to charge smokers buying individual policies up to 50 percent higher premiums starting next Jan. 1.

For a 55-year-old smoker, the penalty could reach nearly $4,250 a year. A 60-year-old could wind up paying nearly $5,100 on top of premiums.

Younger smokers could be charged lower penalties under rules proposed last fall by the Obama administration. But older smokers could face a heavy hit on their household budgets at a time in life when smoking-related illnesses tend to emerge.

Workers covered on the job would be able to avoid tobacco penalties by joining smoking cessation programs, because employer plans operate under different rules. But experts say that option is not guaranteed to smokers trying to purchase coverage individually.

Nearly 1 of every 5 U.S. adults smokes. That share is higher among lower-income people, who also are more likely to work in jobs that don’t come with health insurance and would therefore depend on the new federal health care law. Smoking increases the risk of developing heart disease, lung problems and cancer, contributing to nearly 450,000 deaths a year.

In today’s world, insurers can simply turn down a smoker.

Insurers won’t be allowed to charge more under the overhaul for people who are overweight or have a health condition like a bad back or a heart that skips beats — but they can charge more if a person smokes.

Starting next Jan. 1, the federal health care law will make it possible for people who can’t get coverage now to buy private policies, providing tax credits to keep the premiums affordable. Although the law prohibits insurance companies from turning away the sick, the penalties for smokers could have the same effect in many cases, keeping out potentially costly patients.

"We don’t want to create barriers for people to get health care coverage," said California state Assemblyman Richard Pan, who is working on a law in his state that would limit insurers’ ability to charge smokers more. The federal law allows states to limit or change the smoking penalty.

"We want people who are smoking to get smoking cessation treatment," added Pan, a pediatrician who represents the Sacramento area.

Obama administration officials declined to be interviewed for this article.