Skip to content

Asthma: Definition, Types and Causes [A Complete Review]



Asthma is a chronic disease of the airways. Airways, also known as bronchial tubes, help to transport air to and from the lungs. The disease causes inflammation and narrowing inside the lung, restricting air supply. In this disease, patient’s inside walls of airways, become inflamed or swollen, which make the airways extremely sensitive to the irritations and increases their susceptibility to an allergic reaction.

In an allergic reaction, the airways swell, and the muscles around the airway tighten, making it difficult for air to move in and out of the lungs. No full cure is available, but management methods can help a person with asthma lead a full and active life.

Look : In 1990, asthma patients were around  183 million, which increased to 358 million patients globally in 2015. In 2015, asthma caused about 3,97,100 deaths. The rate of asthma has increased significantly since 1960. In the US, around 8.3% of people have a form of asthma. (✔️)

Symptoms may include shortness of breath, wheezing, chest tightness and coughing


The set of inflammatory events in the respiratory system can lead to the severe symptoms of an asthma attack. Worldwide, around 250,000 people die every year as a result of asthma. (✔️)

Asthma attack occurs when the symptoms are at their peak level. Suddenly, they might begin and can range from mild to severe. In some asthma attacks, swelling in the airways can completely prevent oxygen from reaching the lungs, which also stops it entering the bloodstream and traveling to vital organs.

People With Asthma

This type of asthma attack can be fatal and requires urgent hospitalization. At the start of an asthma attack, the airways allow enough air into the lungs, but it doesn’t let the carbon dioxide (CO2) leave the lungs at a fast enough rate. CO2 is poisonous if your body don’t expel the gas, and a prolonged asthma attack might lead to a build-up of the gas in the lungs.

This might further reduce the amount of O2 (oxygen) entering the bloodstream. People with clear symptoms of asthma should visit a doctor. They will provide treatments and advise on management techniques, as well as identifying potential triggers for asthma symptoms and how to avoid them. Effective asthma control reduces the impact of the condition on everyday living.

There are many types of asthma, as well as a range of factors that can cause the disease. As many different factors come together to cause asthma, there are many different types of the disease, separated by their age and severity.

Adults and children share the same triggers for symptoms that set off an allergic response in the airways, including airborne pollutants, mold, mildew, and cigarette smoke.

1. Childhood Asthma:

Some children might experience daily symptoms of asthma, but the common characteristic among children with asthma is a heightened sensitivity to substances that cause allergy.

Childhood Asthma

Second-hand tobacco smoke also causes asthma in children. According to the American Lung Association, between 400,000 and 1 million children experience worsening asthma symptoms as a result of second-hand smoke. (✔️)

The Centers for Disease Control and Prevention (CDC) advise that children experience more emergency visits and admissions for asthma than the  adults. Mild asthma might resolve without treatment during childhood. However, there is still a risk that this condition might return later, especially if symptoms are moderate or severe.

2. Adult-Onset Asthma:

In adults, asthma is often persistent and requires daily management of flare-ups and preventing the symptoms. Asthma can begin at any age. Allergies lead to at least 30% of adult presentations of asthma. (✔️)

Obesity is a strong risk factor for adult-onset asthma, and women are more likely to develop the condition after the age of 20 years. People over 65 years make up a large number of deaths from asthma.

3. Occupational Asthma:

This is a type of asthma that occurs as a direct result of a job or profession. The symptoms of this asthma will become apparent after attending a particular workplace.

Industries or factories with regular associations to occupational asthma include baking, laboratory work, or manufacturing. In this type of asthma, the work environment leads to return of the childhood asthma or the start of previous one (adult-onset asthma). Other symptoms might include a runny nose and red eyes.

4. Difficult-to-Control and Severe Asthma:

This asthma involve debilitating, consistent asthma symptoms and also the   breathing difficulties. Around 12% of the people with asthma have difficult-to-control or severe asthma. (✔️)

With effective trigger avoidance and correct medication, those in this category can bring asthma symptoms back under the control. Roughly 5% of people with asthma do not see improvements after using the standard asthma medications. Such people have severe asthma, and depending on the cause, there are several types of severe asthma. Newer medications are becoming available to address the different forms of severe asthma, like eosinophilic asthma that doesn’t link to any allergic reactions.

5. Seasonal Asthma:

This type of asthma occurs in response to allergens that are only in the surrounding environment at certain times of year. For example, cold air in the winter or pollen during hay fever season. People still have asthma for the rest of the year but do not experience symptoms.


The following are the primary causes of asthma —

1. Allergies:

A strong link exists b/w allergies and asthma. One 2013 study in the Annals of Asthma, Allergy, and Immunology suggests that over 65% of adults with asthma over the age of 55 years also have an allergy, and the figure is closer to 75% for adults between the ages of 20 and 40 years. (✔️)

Common sources of indoor allergens include animal proteins, mostly from cat and dog dander, dust mites, cockroaches, and fungi.

2. Smoking Tobacco:

Research reveals that tobacco smoke increase the risk of asthma, respiratory infections, wheezing and death from asthma. Smoking makes the effects of asthma on the airways worse by adding breathlessness and coughing to its symptoms, as well as increasing the risk of infections from over-production of mucus.

3. Environmental Factors:

Air pollution both in and out of the home can impact the development and triggers of asthma. Allergic reactions and asthma symptoms often occur because of indoor air pollution from mold or noxious fumes from household cleaners and paints. Anything from pollen to pollution can trigger an asthma attack and inflame the airways. Other asthma triggers in the home and environment include —

  • Pollution
  • Sulphur dioxide
  • Nitrogen oxide
  • Cold temperatures
  • High humidity
  • Ozone

Heavy air pollution tends to cause a higher recurrence of asthma symptoms and hospital admissions. Smoggy conditions release the destructive ingredient known as ozone, causing coughing, shortness of breath, and even chest pain. These same conditions emit sulfur dioxide, which also results in asthma attacks by constricting the airways.

Changes in the weather might also stimulate attacks. Cold air may lead to the constricted airway, airway congestion, extra secretions of mucus, and a reduced ability to clear that mucus. Humidity might also lead to breathing difficulties for populations in some areas.

4. Obesity:

A 2014 study suggest that there is a link b/w obesity and the asthma, although the American Academy of Asthma, Allergies, and Immunology doesn’t recognize the obesity as a formal risk factor for asthma. However, the report in question suggests that inflammatory mechanisms that drive asthma also link to the obesity.

5. Pregnancy:

If a woman smokes tobacco or illicit substances while pregnant, an unborn child might grow less in the womb, have a low birth weight, or experience complications during labor and delivery. These newborns might be more prone to medical problems, including asthma.

6. Stress:

People who undergo stress have higher asthma rates. Increases in asthma-related behaviors during stressful times, such as smoking, might explain these increased rates. Emotional responses, including laughter and grief, might trigger asthma attacks.

7. Genetics:

A parent can pass this decease on to their child. If one parent has asthma, there is a 25% chance that his / her child will develop asthma. Having two parents with asthma increase the risk to 50%. (✔️)

Many genes are involved in passing on asthma. These genes can interact with the environment to become active, although confirming these findings may require further research.

8. Atopy:

Atopy is a general class of allergic hypersensitivity that leads to allergic reactions in different parts of the body that don’t come in contact with an allergen. Examples are hay fever, eczema and an eye condition called allergic conjunctivitis. During atopy, our body produce more immunoglobin (IgE) antibodies than usual in response to common allergens.

9. Menstrual Cycle:

This asthma is also called perimenstrual asthma (PMA). It leads to acute symptoms during menstrual cycle and a particular sensitivity to aspirin.

The sex hormones that circulate during menstruation, such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), impact immune activity. This increased immune action can cause hypersensitivity in the airways.


Leave a Reply

Your email address will not be published. Required fields are marked *