Reviewed by: HU Medical Review Board | Last Reviewed: May 2016. | Last updated: June 2021

Tobacco smoke, whether first- or second-hand, is an irritant that has a considerable effect on asthma symptoms.1 The airways begin to narrow as soon as they are exposed to tobacco smoke.2 Ongoing smoke exposure increases inflammation and airway remodeling overtime.2 Many smokers with asthma have high levels of neutrophils, a type of white blood cell that causes mucus production.1,2 Although there have been few studies, many doctors believe that smokers have more colds than nonsmokers.2 Colds are important triggers for asthma attacks.

How does smoking affect asthma?

To start, smoking increases the risk of developing asthma. Heavier smokers are more likely to develop asthma than lighter smokers.2 A person with a 1 to 10 pack-year smoking history is twice as likely to develop asthma as a non-smoker.3 The risk of developing asthma is 5 times higher for a person with a 21+ pack-year smoking history than a non-smoker. Pack-years are calculated as the packs smoked per day times the number of years as a smoker.

For people who have asthma, smoking tobacco has been shown to:2,4

  • Increase asthma symptoms
  • Decrease lung function
  • Speed up the decline of lung function
  • Decrease the effectiveness of asthma medications (specifically, corticosteroids)

The more you smoke, the more severe your asthma is likely to be.2

How does second-hand smoke affect asthma?

Second-hand smoke can also lead to the development of asthma in children. Young children exposed to tobacco smoke have an increased risk of wheezing and asthma at age 5.1 In fact, the consequences can be seen into adulthood. One study showed that people who were exposed to second-hand smoke as children were nearly twice as likely as others to develop asthma in adulthood.2

Outcomes are much worse for children with asthma if they are exposed to smoke. Second-hand smoke exposure:1,2,5

  • Makes asthma more severe.
  • Increases wheezing and other asthma symptoms.
  • Causes more nighttime asthma symptoms.
  • Increases the risk of asthma attacks, particularly life-threatening attacks.
  • Increases the use of rescue medications.
  • Increases the risk of visiting the emergency department or hospitalizations.
  • Reduced lung function.
  • Decreases quality of life.

Even a little smoke exposure is bad for children’s asthma.6 Children are more affected if their mother smokes than if other members of the household do.1

Adults with asthma who are exposed to second-hand smoke also suffer. They are more likely to have poor control of their asthma symptoms, less lung function, and a lower quality of life. They tend to need more health care.2

How common is smoking and smoke exposure?

In 2013, 17.8% of the total US adult population smoked.7 Smoking is more common in men than women.7

A national survey showed that 46% of adults with obstructive lung disease are current smokers.4 (Obstructive lung diseases includes asthma as well as chronic obstructive pulmonary disease, or COPD.) In the group of people with moderate (or worse) lung disease, 55% smoked.4

Seventeen percent of US teenagers with asthma say that they smoke tobacco.8 Among children and teens (ages 4-19 years) who do not smoke, 53.2% are exposed to second-hand smoke. In this group, 17.6% are exposed to smoke at home.

Reduce exposure to smoke

If you smoke, the best thing to do is to quit smoking. Quitting smoking is important whether you are a person with asthma or taking care of a child with asthma. The benefits of quitting include:2

  • You will have fewer daytime and nighttime asthma symptoms.
  • Your lungs will function better.
  • Your airways will be less sensitive to triggers.
  • You will need less rescue medication and inhaled corticosteroids.
  • Your inhaled corticosteroids will work better.
  • Your asthma-related quality of life will improve.

Even cutting back on how much you smoke can help, although the improvements are smaller.2

It is important for people with asthma to avoid tobacco smoke exposure. Studies have shown that if parents who smoke take steps to reduce tobacco smoke exposure, their children have fewer medical visits.1 Some ways to do this are:1

  • Do not allow smoking in your home or car. Going outside to smoke may not be enough to avoid the risks to children.
  • Do not allow anyone to smoke around you or your child.
  • Be sure that no one at your child’s school or daycare smokes.
  • If you have a choice, try to live in a town or county with smoking bans. People who live in smoke-free counties have less smoke exposure, as measured by byproducts of second-hand smoke in the blood.9 They also go to the hospital less often.5

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