It is important to regularly clean extractor fans. They can be a fire risk. A build up of lint and other combustible detritus can cause fires in fans in bathrooms, laundry rooms or shower rooms etc. Grease and oil build up in kitchen extractor hoods and fans can also cause fire with devastating results.
https://www.coventrytelegraph.net/news/local-news/blaze-warning-after-kitchen-extractor-11868307
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