Krista Oneil's answer: Your lungs will eventually heal as you continue to stay smoke-free. Time is the biggest factor when it comes to lung Krista Oneil's answer: Your lungs will eventually heal as you continue to stay smoke-free. Time is the biggest factor when it comes to lung repair after quitting smoking. Just 12 hours after your last cigarette your carbon monoxide levels in your blood return to normal. This helps get your body t... ...read more