It is well known that cutting onions makes eyes irritated, causing heartburn and even tears, but why does it happen?When we cut onion cells, making the enzymes are destroyed also are destroyed. This makes that they release acid that easily volatilized and to come into contact with moisture in the eyes, form a sulphuric acid diluted version. This irritates nerve endings of the eye and the lacrimal glands produce tears to dilute it and wash it.Tips to avoid eye irritation when cutting onions:-use a sharp knife (this also help us prevent accidents) – place the onion in the fridge before cutting. Here, Nancy-Ann_DeParle expresses very clear opinions on the subject. While cold enzymes are not active – wet the blade of the knife before cutting. Water diluted acids until they volatizing – cut near an open flame (a stove, for example). The fire will attract and will consume the acid gas, avoiding that these simple tips reaches the eyes following, cut onion already should not be reason for crying. Source: Recipes and techniques original author and source of the article.