Evidence continues to mount regarding the danger of second-hand cigarette smoke to non-smokers. Such exposure apparently is more widespread and the risk greater than had been suspected.

A new study presented at an Environmental Protection Agency meeting this week showed that 91 percent of non-smokers tested showed nicotine products in their blood, meaning that they had been exposed to high levels of cigarette smoke within a week of the test.This unexpectedly high percentage means that the health threat from so-called "passive" smoke is more serious than imagined. It also should fuel more demands to prohibit smoking in public places or in the workplace.

The study by Dr. Michael Cummings of the Roswell Park Cancer Institute in Buffalo, N.Y., indicates that non-smokers who spend a lot of time around smokers are running measurable health risks despite their own lack of smoking.

For example, taking Cummings findings into account, studies suggest that non-smoking women married to smokers run twice the risk of lung cancer as women married to non-smokers. And Cummings says children exposed to a parent's cigarette smoke are at even greater risks than non-smoking adults.

The EPA panel that heard Cummings' report is considering a draft report that finds secondhand cigarette smoke responsible for at least 3,700 lung cancer cases a year. The report also would designate such smoke as a class A carcinogen - a known cause of cancer.

If that becomes the accepted EPA standard, a more serious crackdown against smoking in public places would certainly be in order. Smoking is not merely annoying or causing discomfort to nearby non-smokers. It endangers their health as well. No one should have to submit to that.