Select a condition Absence seizures Acne ADHD Age-related macular degeneration AIDS Alzheimer's disease AMD Amebic dysentery Anal tears Angina, stable Angina, unstable Ankle sprain Anorexia Anxiety Appendicitis Arthritis Asthma in adults Asthma in children Athlete's foot Atrial fibrillation Attention deficit hyperactivity disorder (ADHD) Autism Back pain Bacterial vaginosis Bad breath Bedsores Bedwetting Bell's palsy Benign prostatic hyperplasia Bipolar disorder Bladder infection in women Blood pressure Breast cancer Breast pain Bronchiectasis Bronchiolitis Bronchitis Bulimia Bunions Burning mouth syndrome Burns and scalds Canker sores Cardiac arrest Carpal tunnel syndrome Cataracts Cellulitis and erysipelas Chickenpox Childbirth, heavy bleeding Childbirth, tear or cut Chlamydia Chronic bronchitis Chronic fatigue syndrome Chronic obstructive pulmonary disease Chronic prostatitis Chronic tension type headache Cold sores Colic in babies Colon and rectal cancer Colon and rectal cancer screening Colonic diverticular disease Common cold Conjunctivitis Constipation in adults Constipation in children COPD Crib death Deep vein thrombosis Dementia Depression in adults Depression in children Diabetes, type 1 Diabetes, type 2 Diarrhea in adults Diarrhea in children Diverticular disease Ear infection, middle ear Ear infection, outer ear Ear infection with discharge Ear infection with fluid Ear pain during air travel Ear wax Eczema Emphysema Endometriosis Enlarged prostate Epilepsy Episiotomy Erection problems Essential tremor Febrile seizures Fertility problems Fibroids Flu Gallstones Genital herpes Genital warts GERD GERD in children Glaucoma Gonorrhea Gout Group B streptococcus H. pylori infection Halitosis Hay fever Headache, chronic tension type Head lice Heart and circulation problems in diabetes Heart attack Heartburn Heart failure Heavy periods Heel pain Hemorrhoids Hepatitis B Hepatitis C Hernia Herpes, genital Herpes simplex eye infection High blood pressure High blood pressure in pregnancy High cholesterol HIV infection Hyperactivity IBS Incontinence in women Infection in newborn babies Infertility Influenza Insomnia in adults Irritable bowel syndrome Jaundice in newborn babies Jet lag Kidney infection Kidney stones Leg cramps Leg ulcers Lewy body dementia Lung cancer Lyme disease Macular degeneration Malaria prevention Manic depression Mastalgia Measles, mumps and rubella: prevention Melanoma Meniere's disease Meningococcal disease Menopause Migraine in adults Migraine in children MMR prevention Morning sickness Multiple sclerosis Nail infection, fungal Neck pain Nicotine addiction Non-Hodgkin's lymphoma Nosebleeds in children Obesity Obsessive-compulsive disorder OCD Oral thrush Osteoarthritis Osteoporosis Ovarian cancer Painful periods Pancreas cancer Panic attacks Parkinson's disease PCOS Pelvic inflammatory disease Perineal care Peripheral arterial disease Peripheral vascular disease Pneumonia Polycystic ovary syndrome Postpartum depression Postpartum hemorrhage Post-traumatic stress disorder Preeclampsia Pregnancy, nausea Premature birth Pressure sores Prostate cancer Prostatitis, chronic Psoriasis PTSD Raynaud's disease Rectal cancer screening Recurrent cystitis Reflux in children Rheumatoid arthritis Scabies Schizophrenia Seasonal allergy Shoulder pain Sickle cell anemia Sickle cell disease SIDS Sinusitis Skin cancer (melanoma) Skin cancer (squamous cell) Sleep apnea Sleep problems in children Slipped disk Smoking Sore throat Stomach ulcers Stress headache Stress incontinence Stroke, emergency care Stroke prevention Sudden infant death syndrome Swimmer's ear Tennis elbow Tension headache Testicular cancer Thrush (oral) Tic douloureux Tinnitus Tonsillitis Toxoplasmosis in pregnancy Trigeminal neuralgia Underactive thyroid Urinary tract infections in children Varicocele Varicose veins Vascular dementia Warts Whiplash Wisdom teeth, impacted Wrinkles Yeast infection, vagina

Select treatment area Bladder & Kidneys Blood Brain & nervous system Cancer Children's health Diabetes Digestive system Ear, nose & throat Eating & weight Eyes Fertility Heart and circulation Hormones Infections Lungs & breathing Men's health Mental health Mouth Muscles & bones Pregnancy & childbirth Sexual health Skin Sleep Staying healthy Travel health Women's health

Nine out of 10 people who have chronic obstructive pulmonary disease (COPD) are, or used to be, heavy smokers.¹ Breathing in smoke from a smoker near you (secondhand smoke) also can cause COPD.

The poisons in cigarette smoke harm the lungs in many ways. The damage they do leads to COPD. For example, they can make your airways swell up and make them rough and sore on the inside. Then your airways make more mucus and get blocked.

If you give up smoking, your chances of getting COPD go down. But even after about 10 years of not smoking, 1 in 10 people who used to smoke get COPD.

Not all smokers get COPD. A lot depends on how your body handles smoke and poisons. This is controlled by the genes you've inherited from your parents.

Although smoking is the biggest cause of COPD, air pollution can play a part, especially in places where there is a lot of heavy industry.¹ In these areas, there tend to be more harmful particles and harmful gases in the air, such as sulfur dioxide.

Like cigarette smoke, these gases irritate your airways and make them swollen. Then the airways make more mucus. The chemicals also damage the walls of the tiny sacs in your lungs so that they can't hold air so well.

People who work near harmful dusts, chemicals or gases are more likely to get COPD than those who don't.¹ Like cigarette smoke, these things irritate your airways and make them swell. They also increase mucus in the airways and damage the walls of the sacs in the lungs so that they can't hold air so well.

If you work in an industry like farming or mining, where you could be exposed to harmful substances, be sure to follow safety advice to protect your lungs.

If you get a lot of chest infections, you may be more likely to get COPD, especially if you smoke. Getting bacterial or viral infections can lead to chronic bronchitis. If you have that, your lungs produce too much mucus. That makes it harder for you to breathe.¹ See Chronic bronchitis to learn more about this disease.

Smoking is such an important risk factor for COPD, you might think that nearly everyone who smokes would get it. But only about 1 in 5 smokers develop COPD.¹ It seems that some people are more likely to be hurt by cigarette smoke than others.

Doctors think that, somehow, the genes these people inherited from their parents make their risk greater. If you smoke (or used to smoke), and if you have a close relative (mother, father, brother or sister) with COPD, you are more likely to get COPD than someone who smokes but doesn't have a relative with COPD. Scientists don't know yet which genes are involved.

One rare type of COPD is definitely linked to your genes. It is called alpha-1 antitrypsin deficiency, and it causes emphysema, but not chronic bronchitis. See Emphysema for more.

Alpha-1 antitrypsin is a chemical that is made mainly in the liver. Its job is to destroy a protein in the lungs called elastase. Elastase helps to repair old tissue and get new tissue to grow. But it needs to be kept under control by alpha-1 antitrypsin and other chemicals like it. If there is little or no alpha-1 antitrypsin around, elastase can be very destructive. It punches holes in the walls of the little air sacs in your lungs. This leads to emphysema.

Between 1 in 2,000 and 1 in 7,000 people of European descent have alpha-1 antitrypsin deficiency, which they inherited from their parents. The condition is very rare in people of Asian or African descent.¹

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.