Is it better to sniff or blow one’s nose to clear non-infectious secretions?
David Livermore, Cambridge, UK
My father used to induce sneezing during the cold season by tickling his nasal passages. Presumably, he hoped that this would help displace viral particles from his nose into his handkerchief. I wonder whether this was a recommendation at the time of the 1918 flu pandemic, during which he was a small child.
Katherine Conroy, Manchester, UK
A healthy person ingests around 1.5 litres of nasal secretions a day, so sniffing and swallowing isn’t harmful. Any pathogens within the phlegm will be easily neutralised by gastric secretions.
On the other hand, repeated and forceful nose-blowing can generate pressures that are high enough to force mucus into the sinuses, which could be a factor in chronic sinusitis. If you are going to blow your nose, stick to one nostril at a time and do it gently.
Whether you sniff or blow is usually dictated by local etiquette:
Some cultures find public nose-blowing to be abominably rude, while others view sniffing as an intolerable faux pas. Social setting may influence your choice more strongly than physiology.
Harsha Kariyawasam, Royal National ENT Hospital, London, UK
It helps to understand why our nasal system produces secretions. The watery mucus dripping from both nostrils is the release of glandular secretions from the nasal lining at the front of the nose.
A degree of wetness in this area of the nose is healthy. However, when the surface of the nose senses a real or perceived threat, such as the cold virus, cold air or irritants, this can trigger a rapid release of nasal secretions to “trap” the threat and flush it out of the nose. In such circ*mstances, it is best to blow the nose rather than sniff to avoid anything harmful getting deeper into the airway.
Deeper inside the nasal cavity, glandular cells are constantly active and can make more than a litre of mucus in 24 hours. With the help of cilia, tiny hairs on cells that line the airway, this mucus drains towards the back of the nose where it is usually swallowed.
When sinuses become infected or inflamed, this can trigger excess or more viscous mucus production. When this happens, mucus doesn’t easily move to the back of the nose and there is no choice but to try to blow it out. This is easier said than done when the inside of the nose is congested.
“Some cultures find public nose-blowing to be abominably rude, while others view sniffing as an intolerable faux pas”
So it is fine to either sniff or to blow non-infectious secretions depending on which part of the nose (front or back) is producing the mucus.
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