There are more than 4000 chemicals in tobacco smoke 50 are highly poisonous and cancer causing. After 8 hours of quitting,the carbon monoxide level in your blood drops. After 24 hours the chance of a heart attack decreases. After 48 hours your sense of smell and taste improves. After 72 hours your lung capacity increases. After 2 weeks to 3 months your circulation improves and you breath 20 percent better.one year later you've cut your risk of heart disease in half. Now don't get me wrong here i am not trying to say anyone should quit.i just found this so interesting that i had to share plus I have lost too many loved ones over the years from smoking and i am sure you all have.