We're remodeling and found that a lavatory doesn't have a vent. Also we've gutted an addition where we plan to add a kitchen sink and dishwasher. Our building inspector mentioned an air emission vent which can be attached to the drains (within code) and, as long as they're accessible, don't need to be vented to the outside.
This will help a great deal for many people out there who have the same problems of not wanting to punch a hole in their main stack or in their roof. Of course, it will depend on the homeowners local plumbing codes.
I would like to know where I can get more info. about this and if they can be easily installed? thanks for your help.