As I remember from childhood, there was belief that putting a cut onion in the room would help purify the air. Whether it did or not, I don't know but, like others here, I store a cut onion in the refrigerator and haven't gotten sick. When my son was school age, he wanted to take lunches with him but it got difficult coming up with a variety of sandwiches, etc. A home economist recommended using Miracle Whip instead of mayo saying it is salad dressing and not the same ingredients as mayo. She said it was safe to have unrefrigerated during those hours between prep and consumption. Probably best to include a chilled container in the lunch bag though?? I wouldn't trust this theory for salads for picnics as the entire salad would be getting warm, including the eggs. But to spread on a sandwich, apparently Miracle Whip is safe. (He's still alive anyhow!)