Why some non-smokers get COPD: Researchers find that size matters - the size of your airways

  • A study showed strong links between COPD and the size of airways in the lungs
  • Non-smokers with smaller than normal airways had a high risk of contracting the disease as they age
  • Heavy smokers with larger than normal airways tended to be more resilient to developing COPD

It’s universal knowledge that smoking is bad for your health, and that it’s one of the biggest drivers of chronic obstructive pulmonary disease (COPD).

However, it has perplexed scientists why a quarter to almost half of global cases are found in non-smokers, despite accounting for external factors like environment, passive smoking, childhood illness and previous tuberculosis. 

READ: In non-smokers, COPD may up lung cancer risk

A new study published in JAMA may have finally found the answer – and it’s all about the size of your airways in your lungs. 

Partially funded by the National Heart, Lung and Blood Institute (NHLBI) in the US, researchers looked at data from three mass studies, i.e. the Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study, the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS), and the Canadian Cohort of Obstructive Lung Disease (CanCOLD) study.

These studies focused on people over the age of 60 on average, with one study focusing on non-smokers with COPD and another on participants with more than 20 years of smoking. Scans of their lungs looked at the size of their airways, calculating the airway to lung ratio, called dysanapsis. 

These smaller airways, called bronchi and bronchioles, that link to your main windpipe normally grow in conjunction with the size of the lungs, but sometimes they grow too small or too large. 

ALSO READ: Could green tea extract help fight pulmonary fibrosis?

Accounting for other factors like environment and other underlying conditions, the study found that those who never smoked and had smaller than normal airways had a higher risk of developing COPD. 

On the other end of the scale, heavy smokers with larger than normal-sized airways tended to be more resilient to COPD. It makes their lungs more resilient to damage inflicted by smoking.

“This work, stemming from the careful analysis of lung images of COPD patients, shows that an abnormal lung development may account for a large proportion of COPD risk among older adults,” said James Kiley, director of NHLBI’s Division of Lung Diseases. 

“More research is needed to understand what drives this occurrence and to devise possible interventions.”

READ: Are disinfectants putting nurses at risk of COPD?

COPD refers to a group of progressive lung diseases like emphysema and chronic bronchitis that affect breathing. Unlike acute versions – that are temporary and generally caused by infections – COPD is a slow killer that develops over time through inflammation of the lungs and prolonged damage. 

It represents 5% of all deaths in the world according to the World Health Organization’s statistics

Image credit: Pixabay

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