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Unlock This CourseSmoking tobacco is one of the most harmful things you can do to your body, especially your respiratory and cardiovascular systems. When you smoke, you're breathing in over 4,000 different chemicals, many of which are toxic and carcinogenic (cancer-causing). Understanding how smoking damages your body helps explain why it's such a serious health risk and why quitting is so important.
Key Definitions:
Tobacco smoke contains over 70 known carcinogens including formaldehyde, benzene and polonium-210. Carbon monoxide reduces oxygen transport, whilst hydrogen cyanide paralyses the cilia that clean your airways. These chemicals work together to cause massive damage to your respiratory system.
Your respiratory system is designed for gas exchange - taking in oxygen and removing carbon dioxide. Smoking severely disrupts this process through multiple mechanisms that damage lung tissue and reduce breathing efficiency.
When tobacco smoke enters your lungs, it immediately begins causing damage. The hot smoke and toxic chemicals irritate the delicate lining of your airways, causing inflammation and swelling. This makes breathing more difficult and triggers coughing as your body tries to expel the harmful substances.
Smoking paralyses and destroys the tiny hair-like cilia that sweep mucus and debris from your airways. Without functioning cilia, harmful particles accumulate in your lungs.
Irritated airways produce excess mucus to try and trap harmful particles. This thick mucus blocks airways and provides a breeding ground for bacteria.
Constant irritation causes chronic inflammation of the bronchi and bronchioles, leading to swelling that narrows the airways and makes breathing harder.
Long-term smoking leads to several serious diseases that can be life-threatening. These conditions develop gradually but cause permanent damage to your respiratory and cardiovascular systems.
Lung cancer is the most serious consequence of smoking, causing more deaths than any other type of cancer. The carcinogens in tobacco smoke damage the DNA in lung cells, causing them to grow uncontrollably and form tumours.
Smoking causes 85% of all lung cancer cases. A person who smokes 20 cigarettes a day is 20 times more likely to develop lung cancer than a non-smoker. Even passive smoking (breathing in other people's smoke) increases lung cancer risk by 25%.
Emphysema occurs when the walls of the alveoli (air sacs) in your lungs are damaged and lose their elasticity. This reduces the surface area available for gas exchange and makes it extremely difficult to breathe, especially during physical activity.
Toxic chemicals in smoke cause white blood cells to release enzymes that break down the elastic fibres in alveoli walls. Over time, many small air sacs merge into fewer, larger spaces with much less surface area for gas exchange.
Chronic bronchitis involves long-term inflammation of the bronchi, causing a persistent cough that produces thick mucus. The airways become narrowed and scarred, making breathing increasingly difficult over time.
A chronic cough lasting months or years is the main symptom, often called 'smoker's cough'. The cough produces thick, discoloured mucus.
Inflamed and narrowed airways make it hard to get enough air, especially during exercise or physical activity.
Damaged airways are more susceptible to bacterial infections, leading to repeated chest infections and pneumonia.
Smoking doesn't just damage your lungs - it also severely affects your heart and blood vessels, significantly increasing your risk of heart disease and stroke.
Nicotine increases your heart rate and blood pressure, making your heart work harder. Carbon monoxide reduces the oxygen-carrying capacity of your blood, forcing your heart to pump more blood to deliver the same amount of oxygen to your tissues.
Sarah started smoking at 16 and smoked a pack a day for 20 years. At 36, she suffered a heart attack despite being relatively young and active. Tests showed her coronary arteries were severely narrowed by atherosclerosis caused by smoking. After quitting and receiving treatment, her heart function improved significantly.
Smoking accelerates atherosclerosis - the build-up of fatty deposits in artery walls. It also makes blood more likely to clot, increasing the risk of heart attacks and strokes when clots block blood flow to the heart or brain.
The good news is that your body begins to recover as soon as you stop smoking. The healing process starts within hours and continues for years, with significant improvements in lung function and reduced disease risk.
20 minutes: Heart rate and blood pressure drop
12 hours: Carbon monoxide levels normalise
2 weeks: Circulation improves, lung function increases
1 year: Heart disease risk halved
10 years: Lung cancer risk halved
When you quit smoking, your cilia begin to regrow and start clearing mucus and debris from your airways again. Inflammation reduces and your lung capacity gradually improves. Even people with early-stage emphysema can prevent further damage by quitting.
John smoked for 30 years and developed chronic bronchitis. After quitting at age 50, his persistent cough disappeared within 6 months. His lung function tests showed 15% improvement after one year and he could exercise without becoming breathless. His doctor confirmed that quitting prevented progression to emphysema.
You don't have to smoke to be harmed by tobacco - breathing in other people's smoke (passive smoking) also causes serious health problems, especially in children and pregnant women.
Children exposed to passive smoke have higher rates of asthma, chest infections and ear infections. Their developing lungs are particularly vulnerable to damage from tobacco smoke chemicals.
Children of smokers are twice as likely to develop asthma and have more severe symptoms requiring hospital treatment.
Passive smoke weakens children's immune systems, leading to more frequent and severe respiratory infections.
Babies exposed to smoke have increased risk of Sudden Infant Death Syndrome (SIDS) and other serious health problems.
Understanding the severe health consequences of smoking is crucial for making informed decisions about tobacco use. Education about these risks, combined with support for quitting, can save lives and prevent unnecessary suffering.
Smoking kills over 8 million people worldwide each year - that's more than AIDS, tuberculosis and malaria combined. In the UK, smoking causes around 78,000 deaths annually, with half of all long-term smokers dying from smoking-related diseases.