Chronic Bronchitis Risk Factors

What is Bronchitis?

Bronchitis is the inflammation of the bronchi. Bronchi are the tubes in your lungs that allow air to pass in and out.

Bronchitis can be classed as acute or chronic. Acute bronchitis is caused by a respiratory tract infection and lasts only a few days, after which the bronchi return to their usual healthy presentation and function.

What is Chronic Bronchitis? 

Chronic bronchitis is defined as a productive cough or a wet cough (one where you cough up mucus) that lasts for three months or more, for two consecutive years, and can lead to serious complications. Chronic bronchitis is a type of Chronic Obstructive Pulmonary Disease (COPD). Chronic bronchitis is much more serious than acute bronchitis; you may experience daily bouts of severe, productive coughing lasting for months or even years1.

The resulting accumulation of sticky mucus due to chronic inflammation of the airways restricts the movement of air in and out of the lungs. This gets worse over time as the little hairs (cilia) that move phlegm out of the bronchi are damaged, resulting in increasingly severe breathing problems. 

To be diagnosed with chronic bronchitis, you must be coughing up discoloured mucus every day for at least three months, in two consecutive years. Other possible causes of the cough, such as tuberculosis (TB), must also be ruled out.

Many people who have chronic bronchitis develop emphysema, a lung disease where the walls between the air sacs (known as alveoli) break down. Together, chronic bronchitis and emphysema are the most common types of COPD.

Chronic bronchitis risk factors


Smoking is the number one risk factor for COPD, causing about 90% of COPD cases. It causes chronic bronchitis by irritating the lining of the lungs and causing inflammation. Giving up tobacco will not reverse the disease but may slow its progression and improve the effectiveness of some treatments. It may also give the immune system a boost, reducing the impact of recurrent chest infections. 


People with alcohol dependence are three times more likely to be smokers, and as we have established, smoking is very bad for patients with chronic bronchitis.  Regular alcohol consumption may increase your risk of COPD, but the evidence is not clear-cut at the moment. It is certain though, that alcohol impairs the clearance of mucus and other debris from the lungs by hairs (cilia) in your airways.

Occupational or prolonged exposure to lung irritants

This includes second-hand smoke, chemical fumes, dust and air pollution; irritants that cause damage and inflammation, which contribute to the development and progression of bronchitis.


The risk of developing chronic bronchitis increases with age.  Mucus over-secretion becomes increasingly persistent as we age, causing longer courses of productive cough, which are related to quicker reductions in lung function.

Childhood history of respiratory tract infections

Lower respiratory tract infections before the age of 2  are associated with significantly degraded lung function and COPD later in life.


According to a recent editorial, more than 1 in 3 patients with COPD are obese2.  However, it has also been shown that obese patients have less frequent and severe flare-ups, and are less likely to die from COPD complications. This “obesity paradox” is borne out by many studies.


Rarely, a genetic mutation that causes an alpha-1-antitrypsin (AAT) deficiency leads to chronic bronchitis by causing a shortage of a blood protein that helps protect the elastic structure of the lungs from inflammation damage.


  1. Widysanto A, Mathew G. Chronic bronchitis. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 [cited 2022 Jan 1]. Available from:
  2. Iyer AS, Dransfield MT. The “obesity paradox” in chronic obstructive pulmonary disease: can it be resolved? Annals ATS [Internet]. 2018 Feb 1 [cited 2022 Jan 1];15(2):158–9. Available from:

Dr. Richard Stephens

Doctor of Philosophy (PhD), Physiology/Child Health
St George's, University of London

Richard has an extensive background in bioscience and bioinformatics with a PhD in membrane transport physiology and 28 years of experience in scientific publishing, bioscience research and computational biology.
On moving to Cambridge, UK, in 2015, Richard took the opportunity to broaden the application of his scientific background as well as to explore new avenues of interest. Among other things he mentored students at the Disability Resource Centre at the University of Cambridge and is currently working as an educator, pro bono for the Illuminate charity whilst further developing his writing and presentation skills. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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