Can I dive if I am a smoker?

Every diver worth the weight of his or her equipment will tell you that if you are going to dive, then you need to give up smoking.  Besides the increased risk of airway diseases due to smoking, there is also an increased risk of blood carbon monoxide levels and a decrease in arterial oxygen content.  This will cause an increased risk of carbon monoxide toxicity.  The rule of thumb if you are a smoker who dives is that you should abstain from smoking for at least 12 hours before a dive as the half life of excess carbon monoxide in the blood is 6 hours.