It’s not recommended that you use scented candles in the same room as rabbits. Whether scented candles actually could cause respiratory tract damage in rabbits or not, it’s one of those “better safe than sorry” things. That said, unscented candles can also produce unhealthy fumes and soot, so its not just about the scent.

As far as kitchen fumes are concerned, as long as the rabbit doesn’t dwell in the kitchen during cooking, risk ought to be low. There is a danger to human lungs if you, more or less on a daily basis, cook food in oil in high temperatures (i e stir fry-type cooking), but that rather requires that the cook stands over the stir fry and inhales the tiny, tiny droplets of heated oil directly. (This is actually a major cause of lung cancer in non-smoking women in Asia). If you do a lot of stir fry cooking in your kitchen without sufficient ventilation, a greasy film will pretty soon build up on the kitchen surfaces. If you notice this in your kitchen, you should take precautions for the sake of your own health. You could for example switch to cook some things in an air fryer.

The rabbit will most likely not go so near the actual stove while cooking is going on that he or she will be at risk.