What are the effects of smoking just one cigarette a day?

Because of the addictive nature of nicotine, very few people are able limit themselves to "just one". But even "just one" has health consequences. The physical effects of just one cigarette: Your blood pressure increases. Your heart rate increases. Your bronchial tubes constrict making your lungs work harder. The amount of carbon monoxide in your system doubles and prevents oxygen from reaching your vital organs. The temperature of your hands and feet decrease.

The disease profile of habitual smoking includes: cancer, heart disease, stroke, COPD, diabetes, and the list goes on. 

With cancer, the risk of developing a tumor is dose related. So the more you smoke, the longer you smoke, the more likely you would develop cancer. It does NOT mean that you wouldn't get cancer from smoking just one a day, since there are 69 carcinogens in tobacco smoke and there is no safe minimum level of exposure. 

The diathesis-stress model takes into account individual vulnerabilities such as faulty genes. Exposure to intense stress will affect people differently. Some are resilient, while others are not. This can be due to many different  biological factors. If a person with an existing genetic deflect, any exposure could potentially lead to cancer.  There are many people who don't smoke who develop cancer, so why risk it?

However, the risk of heart disease is not dose related. Studies show that between 50% to 80% of the damage to the cardiovascular system happens with the first 3 to 5 cigarettes smoked, especially in someone who has any risk factors for heart disease, which are:

• High blood pressure
• High blood cholesterol
• Diabetes and prediabetes
• Being overweight or obese
• Being physically inactive
• Having a family history of early heart disease
• Having a history of preeclampsia during pregnancy
• Unhealthy diet
• Age (55 or older for women)