Chopping onions is no fun, especially when you have a lot to cut. But most strategies for preventing runny eyes and noses are either scary (holding a burning match in your teeth) or silly (wearing a scuba mask). Is there any hope? Yes, but first you must understand your foe.

Onions engage in chemical warfare "to prevent animals like us from eating them," says Harold McGee, author of On Food and Cooking (Scribner). Like other members of the lily family, onions have a complex cellular structure. Cutting them breaks cell walls and releases chemicals that mix and create an irritating, sulfurous compound.

Refrigerating or chilling an onion slows this process, making chopping more comfortable, McGee says. Rinsing a cut onion under cold water may help. And it may be less irritating if you use a very sharp knife because it damages fewer cells than a dull knife. Lighting a candle or turning on a fan also may help keep caustic gasses away from your face. Or, at the very least, chop as fast as you can and keep the tissue box handy.