Causes of Lung Injuries

Experts don’t always know what the cause is for every lung injury or illness. They do know, however, that there are certain risk factors that seem to contribute to certain cancers and diseases occurring. Below, we discuss some of the causes of lung injuries and the diseases they cause.

Some of the risk factors believed to contribute to lung injuries include:

causes of lung injuries


Smoking cigarettes or other tobacco products is known to be harmful to the human body. Cigarettes are estimated to cause around one in five deaths. In fact, nicotine addiction is the second-leading cause of death worldwide, and is the leading cause of preventable death. 

It is also a known contributor and risk factor for lung cancer

Lung Cancer Canada estimates that 30% of cancer deaths are related to smoking. It is estimated that, each day, 100 Canadians die of a lung-related illness. By and large, around 80-85% of lung cancer deaths are directly related to smoking or exposure to secondhand smoke.

Cigarettes contain nicotine and other ingredients that can be harmful to the body. The primary ingredient in cigarettes, cigars and pipe tobacco is dried tobacco leaves. Tobacco products that are smoked are mixed with a variety of chemicals and additives that are harmful.

Tobacco smoke contains thousands of chemicals, many of which are known carcinogens. A carcinogen is a substance that causes cancer. The most harmful chemicals are tobacco-specific nitrosamines which form during the growing, curing, and aging of tobacco products. When tobacco is cured with heat, polycyclic aromatic hydrocarbons are produced.

Cigarettes, cigars and pipe tobacco contain chemicals that are known to cause cancer, lung disease, heart disease, stroke and other health problems.

These chemicals include:

  • Nicotine (an additive that produces the brain effects that people look for when smoking)
  • Hydrogen cyanide
  • Lead
  • Arsenic
  • Formaldehyde
  • Ammonia
  • Benzene
  • Carbon monoxide
  • Polonium-210 (a radioactive element)

Many of these substances are emitted from the burning tobacco leaves. Some are the result of the growing process, such as fertilizer and soil that the tobacco was exposed to. Others are the result of the additives and chemicals added to the products. These poisonous chemicals can weaken the immune system so our bodies cannot fight cancerous cells. The poisons can also alter normal DNA in cells and prevent normal function, often causing cells to grow out of control.

Smokeless Tobacco Products

Smokeless tobacco products kill less people each year than smoked products, but they are still very dangerous. These products are often touted as being safer, but the truth is that they contain many of the same hazardous substances as cigarettes or cigars.

Smokeless tobacco, such as snuff and chewing tobacco, can also be bad for you, and can cause certain types of cancer. Unlike cigars and cigarettes, smokeless tobacco products are put in the nose or mouth. Instead of being inhaled, chemicals and carcinogens are absorbed through the soft tissues in the nose or mouth.

Smokeless tobacco causes cancer of the mouth, esophagus, and pancreas. It can be associated with white plaque formation in the mouth called leukoplakia. It is associated with early delivery and stillbirth in mothers using smokeless tobacco products. It can increase the risk of heart disease and stroke.

Some of the more common smokeless tobacco products that are dangerous include:

  • Snus (pronounced ‘snoose’) is a moist variety of snuff. With snus, there is no spitting. Originally from Norway and Sweden, snus does not contain as much nicotine as other varieties of snuff.
  • Dissolvable tobacco products are another way that people intake nicotine and potentially harmful chemicals. Dissolvables include strips, orbs, pellets, gum and lozenges. While these products are not smoked, the nicotine and other chemicals are still a risk factor for lung injuries.
  • Heated tobacco products are another variation of smokeless products. These products usually involve a heating element that heats up special plugs, capsules or sticks designed for the product. These items contain tobacco, nicotine and many of the chemicals present in cigarettes. The concentration of chemicals may be lower, but they are still a risk factor.

Smokeless tobacco products are linked to a variety of harmful health conditions, including heart disease, oral lesions, oral cancer, gum disease and lung cancer. The ACS also notes that there is no proof that smokeless tobacco products help people quit smoking.

Secondhand Smoke

If you live with or work around someone who smokes tobacco products regularly, you are likely being exposed to secondhand smoke. Secondhand smoke can be mainstream (exhaled by someone who is smoking), or sidestream (smoke emitted from a lit cigarette, cigar, pipe or hookah). In either case, people who do not smoke but who are exposed to secondhand smoke are at risk for many of the same lung injuries as those who smoke.

Secondhand smoke contains nicotine and chemicals just like cigarettes and other tobacco products. Breathing in secondhand smoke is almost as dangerous as actually smoking. In fact, it is called passive or involuntary smoking. The exhaled breath of someone smoking can contain 7,000 chemicals. At least 70 of those are potentially cancer-causing.

Secondhand smoke is one of the major causes of lung cancer among people who have never smoked. The Canadian Cancer Society estimates that 800 people die each year from secondhand smoke-related illnesses. It can also cause cancers of the sinuses, larynx, breast, leukemia and brain tumors. Secondhand smoke also increases the risk of certain medical conditions, including:

  • Heart attack
  • Heart disease
  • Stroke
  • Asthma
  • Frequent infections

Scientists are also working to determine if secondhand vapor from exhaling e-cigarettes is also harmful. There is evidence suggesting that exhaled aerosols are not harmless, but the research into how dangerous it may be is ongoing.

Exposure to Asbestos

Asbestos is a mineral that has been used for generations for various purposes. It is incredibly heat-resistant and strong, lightweight and does not conduct electricity. While it was very commonly used as an insulator for homes, ships, schools, factories and automobiles, during the first part of the 20th century, it became apparent that asbestos was making people sick.

By the latter part of the 20th century, asbestos was definitively linked to certain types of cancer and governments began limiting its use. In Canada, however, the government continued to permit production and use of asbestos, even when the United Nations implemented a Union-wide ban. In 2018, Canada passed the Prohibition of Asbestos Products Containing Asbestos Regulations, but still, there are certain exceptions that allow asbestos to be used.

What is Asbestos?

Asbestos is a mineral that occurs naturally. It is a group of tightly-woven fibers that is common in many parts of the world in soil and rocks. Asbestos is primarily made of silicon, oxygen and other elements.

There are two types of asbestos:

  • Chrysotile: Chrysotile asbestos, also called white asbestos, is the more common type of the mineral used commercially. Under a microscope, the fibers appear to wind around themselves, also lending to the names curly or serpentine asbestos.
  • Amphibole: Amphibole asbestos has straight fibers that are needle-like. There are several varieties of amphibole asbestos, including crocidolite (blue), amosite (brown), tremolite and anthophyllite.

Exposure to asbestos most often results from inhaling fibers in the air, or swallowing fibers that contaminate food or liquid. Most exposure occurs when people work around asbestos, such as in construction or shipbuilding. Asbestos can create a dust that is easily inhaled, especially in areas with limited ventilation.

Families of workers exposed to asbestos can also be exposed secondhand. When a worker comes home with asbestos fibers in his or her clothing, it can shed into the home and be breathed in by other family members. People can also be exposed if they live or work in an older building that has asbestos in the walls or ceiling.

Causes of Lung Injuries from Asbestos

Exposure to asbestos can cause:

Mesothelioma is the lung injury most often linked to asbestos. It is an aggressive type of cancer that develops in the mesothelium. The mesothelium is a thin layer of tissue that protects the lungs and other organs in the body. While most common in the lungs, mesothelioma can occur in other organs.

Asbestos is the only known risk factor for mesothelioma. It is unclear how the asbestos fibers cause cancer and there are some mesothelioma patients who have not had clear exposure to asbestos. Unfortunately, mesothelioma is characterized by poor response to therapy and poor prognosis. There is no known cure. 

Most patients who present with mesothelioma are already at the advanced stages (Stage 3 or 4). They are diagnosed because of trouble breathing, chest pain, persistent cough, fatigue, trouble sleeping, weight loss, or a chest mass.There are also studies suggesting that asbestos exposure may cause other cancers, including those involving the gastrointestinal tract.


Scientists believe that genetics can be a factor in developing certain types of lung cancer. DNA is what makes up our genes. Genes are what controls how cells function in the body. Genes help control how cells grow, stay alive or divide (oncogenes). They also help control and monitor cell division (tumor suppressor genes).

If we inherit certain genes from our parents, it can impact our risk for developing cancer or other diseases. Some people inherit certain DNA mutations from one or both parents, which can increase the risk of developing cancer. For example, someone with certain DNA changes in, say, chromosome 6, may be more likely to develop lung cancer, even if they never smoke.

Other people may inherit genes that affect how their body breaks down or eliminates chemicals in the body, which can also impact the risk of developing cancer. Also, some people are born with an abnormal EGFR gene, which means they produce too much EGFR protein – a protein that can lead to NSCLC.

All patients with non-small cell lung cancer should undergo genetic testing for EGFR, KRAS, anaplastic lymphoma kinase (ALK), ROS 1, and programmed death ligand-1 (PDL-1). The results will help determine if a patient is eligible for treatment with specific molecular-targeted agents such as osimertinib or alectinib.

Exposure to Carcinogens

A carcinogen is a compound, substance or chemical that is known to cause cancer. Sadly, many people are exposed to carcinogens without realizing it. Most often, this happens in the workplace when people are exposed to hazardous materials without proper personal protective equipment (PPE). People who smoke or are around cigarette smoke are also exposed to carcinogens and may not realize the danger.

Some of the carcinogens that can lead to lung cancer include:

  • Arsenic
  • Beryllium
  • Chromium
  • Diesel exhaust
  • Nickel
  • Soot
  • Tar

Even people who don’t smoke are at risk of developing cancer if they are exposed to carcinogens. People who smoke, however, are much more likely to develop lung cancer if they are also exposed to these hazards.

Exposure to Radon

Radon is a type of gas that is emitted from the ground due to the natural breakdown of uranium in rocks and soil. Radon gas has no color or odor. It is present in the environment naturally in trace amounts, but can build up in buildings and homes if there is not a proper barrier to prevent it from leaking in. Professionals who build or inspect homes can test the home for radon and can remediate if it is present.

When radon breaks down, it turns into radioactive elements called radon progeny. These elements include polonium-218, polonium-214 and lead-214. These progenies can then attach to dust, which can then be breathed in. As radon breaks down in the air, it gives off radiation that can damage DNA in the body.

How Dangerous is Radon?

Exposure to radon for a long time can cause lung cancer. The Environmental Protection Agency (EPA) estimates that, each year, around 21,000 people die due to radon-related lung cancer. In Canada, around 16% of lung cancer deaths are related to radon exposure. Each year, more than 3,300 people die from radon-related lung cancer.

Other than smoking, radon is the leading cause of lung cancer. The World Health Organization (WHO) estimates that, globally, radon is responsible for around 14% of all lung cancer deaths, accounting for around 189,000 deaths each year. 

There are proven ways to prevent radon gas from entering buildings and homes, but sadly, a lot of structures do not have these barriers in place. As a result, radon builds up in the interior and wreaks havoc on the people inside.

Exposure to Radiation

Radiation is a form of energy. It travels in high-speed particles or energy wages, and can occur both naturally and synthetically. There are two types of radiation:

  • Ionizing: Ionizing radiation is radiation emitted from a source. This includes ultraviolet radiation from the sun (UV), radiation from X-ray tubes or even radiation emitted by a microwave. 
  • Non-Ionizing: Non-ionizing radiation is radiation emitted by energy wages or fields. This includes:
    • Ultraviolet (UV): Emitted from the sun, welding arcs, UV lasers and black lights.
    • Infrared: Infrared radiation (IR) is emitted from heat sources, such as heat lamps, furnaces and IR lasers.
    • Microwave and Radiofrequency: Microwave radiation can be absorbed through the skin, while radiofrequency radiation can be absorbed through the entire body. MW and RF radiation are emitted from cell phones and radio emitters.
    • Extremely Low Frequency Radiation: ELF is a type of radiation that is produced from electrical wiring, power lines and electrical equipment. 

Radiation exposure is a hazard to workers in many industries.

Exposure to Crystalline Silica Dust

Workers in many industries are exposed to crystalline silica dust. Silica is a mineral compound that is present naturally in dirt, rocks and sand. When the mineral is worked, it produces tiny particles of silica dust that can be inhaled into the lungs. Silica dust exposure is very common in industries like construction, foundry, fracking sand, mining, sandblasting and granite work. Workers who do not use personal protective equipment (PPE) can inhale a lot of silica dust, or a little bit over an extended period of time. These particles enter the lungs and are difficult to exhale back out. Over time, workers can develop serious lung injuries, including silicosis. Silicosis causes what is known as pneumoconiosis involving fibronodular lung disease. There is no therapy that stops or cures the disease, therefore prevention is essential.

Learn More about the Causes of Lung Injuries

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Drew Sutton, MD

Reviewed By Drew Sutton, MD

Drew Sutton, MD is a board-certified otolaryngologist. He has extensive experience and training in sinus and respiratory diseases, ear and skull base surgery and pulmonary disorders. He has served as a Clinical Instructor at Grady Hospital Emory University for more than 12 years. He is a medical reviewer and contributor at