Richard Doll, 92, the British scientist who was among the first researchers to show a dramatic connection between lung cancer and smoking, died July 24 at John Radcliffe Hospital in Oxford, England. No cause of death was reported.

When Sir Richard began his research, smoking had long been considered a vice and a contributor to numerous ailments, including cancer of the lip. But scientific warnings were tepid and widely ignored. After World War II, British male doctors smoked nearly as much as anyone else.

As an epidemiologist -- a scientist who studies the roots of a disease through statistics rather than chemistry or biology -- Sir Richard became involved in postwar British efforts to determine the cause of the worrying, unexplained leap in lung cancer cases. He himself had enjoyed cigarettes since youth, but he came to consider the habit foolish ("a mug's game") after his groundbreaking research.

The public reaction in the early 1950s was muted, but he gradually was honored for his work. Last year, his lung cancer study in the British Medical Journal showed detailed and long-term results supporting his earlier findings. He concluded that a cigarette smoker, on average, will live 10 years less than a nonsmoker.

William Richard Shaboe Doll was born Oct. 28, 1912, in Hampton, on the River Thames west of London. His father, a general practitioner, once promised him 50 pounds if he shunned cigarettes until he was 21. But a younger brother taunted him whenever they saw adults smoke. "When I was about 18, I said: 'I cannot stand this any longer. Give me a cigarette.' And I started smoking."

He also rebelled against his father's wish to study medicine, which the elder Doll considered a stable trade during the economic depression of the early 1930s. Sir Richard's early interest was mathematics, but beer intervened one night.

"I went up to take the open scholarship in mathematics and met some so-called friends who gave me dinner at Trinity College," he told the London Observer in 2002. His pals brewed beer of 8 percent alcohol -- too tempting to resist. The next day, he failed his entrance exams.

He then caved to his father's wishes.

After finishing his schooling at St. Thomas Hospital Medical School in London, where he was active in groups that campaigned against poverty and fascism, Sir Richard served in the Royal Army Medical Corps. He saw action at Dunkirk before serving on a hospital ship in the Mediterranean.

At war's end, he returned to St. Thomas but winced at the deference he was expected to pay senior staff. He became a researcher and focused on epidemiology.

His timing was ideal. The British Medical Research Council, similar to the U.S. National Institutes of Health, began funding research into high rates of lung cancer. Working under pioneering statistician Austin Bradford Hill, who became his mentor, Sir Richard helped sift through an assortment of theories.

"My own guess was that it had something to do with motorcars," Sir Richard once told The Washington Post, noting that coal tars used to pave roads had been shown to have carcinogens.

Most promising, he studied the lives and habits of patients at London hospitals, many of them with lung cancer. "I found that in cases where a cancer diagnosis was wrong, the patient always turned out to be a non-smoker," he told the Observer. "But when the diagnosis turned out to be correct, the patient was always revealed to be a smoker."

They eventually took their study beyond the thousands of patients they reviewed in London, spending nearly three years on their research before publishing their findings in late 1950.

Meanwhile, two similar studies focusing on smoking and lung cancer appeared in the Journal of the American Medical Association. Sir Richard seemed unperturbed by losing "first place," saying that "it's equally important not to spread scares. I think if you obtain a rather unexpected finding, the right thing to do is repeat it before publishing."

He needn't have worried about scaring anyone, for hardly anyone took notice, he said. It seemed as if without conclusive proof of a link between smoking and lung cancer, there was little alarm among public health professionals.

Sir Richard and Hill broadened their studies, which supported their results. The research council formally accepted the causal connection between smoking and cancer in 1957.

Starting in the 1950s, Sir Richard also investigated the link between disease and environmental risks, from ionizing radiation to the safety of oral contraception. He said the cancer-protecting benefits of the birth control pill outweigh the risk of blood clots in the legs.

In 1969, the prime minister appointed him Regius professor of medicine at Oxford University. He was knighted for his work.

His wife, Joan Faulkner Doll, died in 2001. Survivors include two children.

Although he once said that to work for the tobacco industry was "as immoral as keeping a brothel," he was far less dogmatic about an individual's right to smoke. "I don't mind in the least if someone in the room lights up a cigarette,'' he told the Journal of Addiction in 1990. "It's their decision and their life, not mine.''

Public reaction to Richard Doll's research was muted in the 1950s, but he gradually was honored for groundbreaking cancer studies.