Los Angeles ? Watching television for hour upon hour obviously isn’t the best way to spend leisure time — copious inactivity has been linked to obesity and heart disease. But now a new study quantifies TV viewing’s effect on risk of death.

Researchers found that each hour spent watching TV was linked with an 18 percent greater risk of dying from cardiovascular disease, an 11 percent greater risk of all causes of death, and a 9 percent increased risk of death from cancer.

The study, released Monday in Circulation: Journal of the American Heart Association, looked at health data among 8,800 men and women aged 25 years or older who were part of the Australian Diabetes, Obesity and Lifestyle Study. Participants recorded their television viewing hours for a week, and researchers separated the results by amount of viewing: those who watched less than two hours of TV a day, those who watched two to four hours a day, and those who watched more than four hours a day.

The subjects also had oral glucose tolerance tests to determine blood sugar and gave blood samples to establish cholesterol levels at the beginning of the study. People with a history of cardiovascular disease were not included in the study. In more than six years of follow-up, 87 people died of cardiovascular disease and 125 of cancer.

Researchers found a strong connection between TV hours and death from cardiovascular disease. That link was found not just among the overweight and obese, but also among people who had a healthy weight and exercised.

People who watched more than four hours a day showed an 80 percent greater risk of death from cardiovascular disease and a 46 percent higher risk of all causes of death compared to those who watched less than two hours a day, suggesting that being sedentary could have general deleterious effects. The numbers were the same after the researchers controlled for smoking, high blood pressure, high cholesterol, an unhealthy diet and leisure-time exercise.