Onions release a gas called syn-propanethial-S-oxide, which irritates the eyes and triggers tearing as a biological response to protect them from the irritant. Various remedies exist to alleviate this reaction, with some suggesting moving away from the onion to allow the gas to disperse. Wearing goggles is also a common recommendation. An alternative method mentioned involves inhaling the onion's smell deeply, which initially causes tears but may help reduce irritation after a few moments, provided the onion remains intact during cutting.