If you do not have a provision in your tenancy agreement regarding health risks or incineration/fire, I would inform the tenant #2 (in writing, by letter authenticated and placed at their door) that their actions pose a potential risk to the health of the tenants #3 and that they are required to cease and immediately impose the incense incineration in their unit. I would add that I will waive any tax for early termination for the next 30 days (communication to be provided within 3 days) if they wish to move and find an establishment allowing them to burn incense. But just because a lease clause does not explicitly mention candles, incense sticks and oil burners does not mean that they are not already covered. For example, for most professionally developed leases, there will be a fire protection clause. Assuming that your tenancy agreement has an appropriate clause with respect to fire protection, while your tenants also do not realize that the candles are covered, etc., I suggest you write to them to explain it. If so, should your letter, can I only inform the tenants or should it have been written in the contract in order to be able to apply it? Thank you very much. Of course, smoking is prohibited in the building, but can I ban the use of candles, incense sticks and oil burners, etc. (electric fire itself)? “NO PETS ALLOWED Anywhere on the site without the prior consent of the owner, whether or not they belong to the tenant. If the tenant is found to be lesioned, the landlord can a.) a tax of -per night b.) find the tenant in a counterfeit contract and initiate eviction proceedings. In fact, it is dangerous to give a list of prohibited items in a rental agreement, because it means that everything else is allowed! Although lawyers solve this problem by listing words such as “included, but not limited to … If I were the tenant on the third floor, I wouldn`t want incense or scented candles to come into my apartment, because I`m very sensitive to smells, but bringing it up to the threat of a combination of allergy discrimination is a huge red flag to take seriously. If it comes with a doctor`s letter that can be checked by the doctor`s office, you may need to figure out how best to seal the units, provide a filter of any type, or whatever a suitable accommodation asks you if it`s not hard for you to do so.