When I sneeze, everyone knows about it. The resulting shockwave wobbles windows, awakens sleeping animals, and sets nearby humans on edge. My partner, who sneezes like a vole hiccuping, insists I do this on purpose. I maintain that the urge to sneeze at this decibel level is irresistible. Why do some people sneeze so loudly? 

What happens when we sneeze?

Let's establish one thing first: Sneezing is important for the body. "The nose is an air filter for the lungs," says Mas Takashima, the chair of the Department of Otolaryngology, Head and Neck Surgery at Houston Methodist Academic Institute. Inside our nose is a tight mesh of epithelial cells (a multipurpose cell found all over the body), tiny hairs, and thick mucus. These elements, says Takashima, "trap particulates so that the lungs can be protected." When those particulates build up, they need to be flushed out.

There are also populations of immune cells in our nose, which wake up when they detect high levels of sneeze-inducing compounds. "Some of the chemicals that are made as a consequence of that immune response cause changes in the lining of our nose," says Sheena Cruickshank, a professor in the University of Manchester's Division of Immunology. Those changes will be familiar to anyone who has endured a pollen-laden summer or phlegmy winter. The body makes more mucus, swelling starts in the nose, and signals are sent to the brain via the trigeminal nerve, which provides sensation to the face. This signal is processed by an area at the base of our brain called the medulla oblongata, resulting in reflexive muscle contractions. This all leads to a sneeze. But while the causes of sneezing vary, there's no reason a virus should produce a louder sneeze than grass pollen, says Cruickshank.