Causes & Risk Factors

Reviewed by: HU Medical Review Board | Last reviewed: July 2021.

Chronic obstructive pulmonary disease (COPD) is often caused by inhaling irritants. Of all inhaled irritants, COPD is most commonly caused by smoking. It can also be caused by inhaling fumes, chemicals, dust, and other pollutants.1


Smoking tobacco is the No. 1 cause of COPD in the United States. It is estimated that about 1 in 5 current or past smokers will develop COPD. The risk of developing COPD increases the longer and more regularly you smoke. However, the risk also falls if you quit smoking.1,2

An increased risk of COPD has been linked to many types of tobacco products, not just cigarettes. Pipe or cigar smokers are also at a higher risk. Even marijuana smokers may be at a higher risk for COPD. If you do not smoke yourself but have been around a lot of secondhand smoke, you are also more likely to develop COPD.1-3

Other types of irritants

Other types of irritants can also cause COPD if you are regularly exposed to them at work or home. At work, some examples of materials you may be exposed to include:1

  • Carbon monoxide
  • Ammonia
  • Asbestos
  • Dusts
  • Fumes

It can take a long time for exposure to these materials to cause COPD. But it does not hurt to be aware of your workplace’s air quality.

Irritants can also be found in your home. These might include:1

  • Dust
  • Smoke
  • Harsh cleaners or spray products
  • Mold and bacteria

In some parts of the world, it is more common to burn fuel inside for cooking and heating. People exposed to these fumes are at a higher risk for COPD.2,3

High levels of air pollution are known to worsen COPD and increase the risk of developing it. Air pollution is more common in urban areas and worse along busy roads.1


Genetics can also impact who develops COPD. Some people are born with a rare genetic condition called alpha-1 antitrypsin (AAT) deficiency. People with AAT deficiency have livers that do not make enough of a certain kind of protein called AAT.1,2

This protein’s job is to help protect the lungs from damage. Because they do not have enough AAT to protect their lungs, breathing irritants can be very harmful for people with AAT deficiency. People with AAT deficiency are also much more likely to develop COPD if they smoke. AAT deficiency is very rare, but it is easy to diagnose with a blood test.1,2

Some people with COPD have never been exposed to irritants and do not have an AAT deficiency. For this reason, scientists think the tendency to develop COPD might be passed down in families through other genes. Researchers have also identified some of the genes that may have a relationship to COPD. However, more research is needed to fully understand the role these genes could have in COPD.1,2

Other risk factors

There are other factors that may increase the chance of developing COPD. Some people who may be at higher risk for COPD include:2

  • People with asthma, especially if it is untreated for a long time
  • People with atopy, a type of sensitivity to allergens
  • Smokers older than 40
  • Smokers who are not physically active
  • Women, since they are slightly more likely than men to develop COPD

All these risk factors can work together to increase the risk of COPD overall. For example, when any risk factors are combined with smoking, the total risk increases even more.2

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