The chemical residue left on your indoor herbs from the second hand smoke film that settles on their leaves can significantly impair their ability to take in fresh carbon dioxide and expel oxygen. If their stomata (the pores that they "breathe" through) become clogged, your Basil may not be processing carbon dioxide healthily. The film/dust left by habitual second hand smoke can also affect the photosynthesis process by coating the leaves and preventing enough light from reaching them, which may result in wilting, discoloration and ultimately death of your herb plant. You can try keeping them in a separate room away from constant smoke, as well as taking a wet cloth and gently wiping both sides of the foliage to try to free the stomata of any chemical build up. Make sure to thoroughly wash and dry the leaves before cooking with them to try to avoid any contaminants from the smoke, though I don't know if it may change the flavor.
Ahh, gotcha! Just keep those tips about the smoke in mind for any indoor herb plants. If you keep herbs or plants indoors a good routine dusting and cleaning with a damp cloth is a great idea once in a while to help them breathing and processing nutrients more efficiently. A damp cloth is better than spraying the plants directly with water, as the added moisture may fall into crevices of the leaves and breed fungus. Best of luck and happy gardening!