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Air purifiers filter the content and the stench of air, erasing the stink of tobacco smoke.  This will help you conceal your smoking when indoors.  The best air purifiers will have an activated carbon filter.  This filter is specially attuned to remove the odor of smoke. If you’re out and about but trying to not get caught smoking indoors, use a personal air filter.  These portable devices filter your smoke, scrubbing its scent and toxins. Smoke clings to clothes, curtains, towels, and bedding.   Remove these things regularly before they build up a heavy layer of smoke that could out you as an indoor smoker. Smoke particulate can mingle with regular dust and settle on your tables, TVs, and counters.  Dust and wipe surfaces regularly to avoid accumulating telltale smoke scent. Don’t forget to wipe down your mirrors and windows. Don’t leave your cigarettes in the toilet or on top of an open trash can.  Wrap your cigarette butts in a damp paper towel to ensure they don’t accidentally ignite the trash can, then throw the whole bundle away. If you’re indoors and head off on your own, have a good pretext.  For instance, you might smoke when you’re running documents to another part of your workplace.  Smoke only during periods of time when you won’t be missed.  Smoking indoors when on your way to your lunch break, for instance, is a good option. If you’re in a room with a fan or air conditioner, turn it on.  The movement of air can disperse the smoke, making it harder for others to detect.  This will reduce the likelihood you’ll get caught.
Get an air purifier. Do the wash regularly. Dust your residence. Clean up your butts. Don’t let anyone suspect you go to smoke. Turn the fan on.