Cigarette smoking remains stubbornly high among workers in the mining, food services and construction industries despite dramatic overall declines in the United States in recent decades, a federal study showed.

Thirty percent of workers in mining, hotel/motel and food services smoke, according to the Centers for Disease Control and Prevention, which analyzed data from 2004-2010.

The construction industry had the next highest smoking rate at 29.7 percent.

"Since the first surgeon general's report in 1964, we've almost cut the smoking prevalence in half overall," said Ann Malarcher, senior scientific adviser at the CDC. "But then there are groups that are still at very high rates and are being left behind."

The management and education sectors had among the lowest percentage of smokers. Only 9.7 percent of educators smoke, according to the study.

Low education levels are a factor in high smoking rates, along with poverty and gender, Malarcher said.

"One of the things that has been studied is that persons with lower levels of education tend to have less access to health information," she said. "They tend to be less knowledgeable about the dangers of tobacco use."

The CDC survey found the highest smoking rates among workers ages 18-24, males, those with high school or less education and those without health insurance. Midwestern workers had the overall highest rates.

The CDC recommends that employers increase their anti-smoking efforts, including imposing smoke-free workplace policies and providing health insurance coverage for smoking cessation treatments.

Adult smoking has decreased 42.4 percent since 1965, the CDC said. But the decline has slowed in the past five years, dropping to 19.3 percent of adults in 2010 from 20.9 percent in 2005.

Smoking and exposure to secondhand smoke is the leading cause of preventable death and disease in the United States, killing an estimated 443,000 Americans each year. Smoking costs about $193 billion annually in direct health care expenses and lost productivity.