He has had 275 articles printed on flatulence in medical journals, as either the principal author or the co-author.In fact, Levitt's career could only happen in America.Every day he receives at least one long-distance phone consultation from a worried farter, almost always a man whose wife has prompted her husband to find out why he cuts the cheese so often.

When I told my wife I was going to write a story about farts, she said that if I mentioned her name I was dead meat. My wife does fart and she farts loudly but, thank God, her farts are mostly odorless. To understand the nuances of farting, or flatulence, I called upon Dr. Levitt, a gastroenterologist and associate chief of staff at the Minneapolis Veterans Affairs Medical Center. Fart because he is the world's leading authority on flatulence.

The amount of gas and the volume at which a fart is expelled are another issue.

The majority are made up of nitrogen, oxygen, carbon dioxide, hydrogen and methane -- all odorless.

As anyone who has been to summer camp knows, methane, even in small amounts, can torch a match.

"Every cocktail party I go to, I always get at least one wife who comes up to me and complains about her husband's farts."To clear the air (there will be no more puns in this story), Levitt says that his research has shown that on average the normal number of flatulatic occurrences a day is 10.

There are scores more, but they are all internal explosions and since this gas technically never leaves the body, it can't really be considered flatulence.

Levitt notes that if you have on average more than 22 separate flatulent occurrences a day, then you may want to consider several things: what you eat, how fast you eat it and how much air you swallow when you eat or drink.

In his 40-year career, Levitt has seen only two patients (both men) who farted upward of 140 times a day, but these extraordinary cases were lactose-intolerant individuals and, once dairy products were cut out of their diets, they returned to the normal range of acceptability. One of them complained that his sex life had been ruined by his chronic farting," Levitt says.

There are four possible reasons why some people fart more than others: They eat a lot of carbohydrates; they swallow air when they eat; the bacteria in their intestines are more efficient in turning carbohydrates into gas; or, conversely, the bacteria in their intestines don't consume carbohydrates efficiently, and therefore produce gas.

Levitt says an average male fart is made up of about 110 milliliters of gas (almost half a cup), with 80 milliliters for a woman's (a third of a cup).

Some people are able to absorb and tolerate the gas they produce better than others.