Dyspnea also known as shortness of breath, occurs when a person feels that they are unable, or less able than usual, to take enough air into the lungs.
The sensation of shortness of breath is subjective. For instance, some people may describe the feeling as a sensation of suffocating. For others, they may feel unable to take a deep breath.
Regardless of the exact description, experiencing shortness of breath is uncomfortable and may lead to additional symptoms or complications.

Shortness of breath may occur occasionally or frequently, and it has many different potential causes.

Causes
Many people experience shortness of breath during and after exercise. It can also occur due to changes in altitude or temperature.
Usually, however, there is more than one cause of shortness of breath.
Shortness of breath has a large variety of possible causes. The most common include:
anxiety, asthma, heart failure, interstitial lung disease, pneumonia, chronic obstructive pulmonary disease (COPD)

People may also experience this condition in a different situation, for instance  in children Dyspnea can be as a result of rigorous physical activity like exercise but in some cases it may be a symptom of an underlying condition such as: asthma, lung disease, a heart problem, pneumonia.

When to contact a doctor
A person should contact a doctor if a child is short of breath and:
starts to wheeze
cannot sleep due to breathlessness
is out of breath while resting

In older adults
older adults have an increased risk of developing certain conditions that may lead to shortness of breath.
For example, increased age is a risk factor for conditions such as congestive heart failure and COPD, both of which may cause shortness of breath.
When to contact a doctor
An older adult should contact a doctor if they experience breathlessness and:
chest pain or discomfort
dizziness or fainting

In Pregnant Women
Some people experience shortness of breath during pregnancy. Shortness of breath may develop in both early and late pregnancy, but for different reasons.

During early pregnancy, shortness of breath may develop due to an increase in progesterone. This increase in progesterone can cause a person to breathe more often. An increased respiratory rate may lead to a sensation of shortness of breath.

In later pregnancy, as the uterus grows, it can push up on the lungs. This growth of the uterus can lead to a decrease in full lung expansion and a feeling of shortness of breath.

When to contact a doctor
A person should contact a doctor if they are pregnant and experiencing shortness of breath alongside:
a fast heart rate, heart palpitations, dizziness, chest pain, blueness around the lips, fingers, or toes, persistent cough, coughing up blood, fever or chills and worsening asthma

Common triggers
What triggers shortness of breath in some people may not trigger it in others. However, some common triggers include:
Exercise: Physical exertion, such as exercise, often causes an increase in breathing and possibly shortness of breath.

Intense emotions: Strong emotions, such as fear or panic, can lead to difficulty breathing and feelings of breathlessness.
Change in altitude: Air pressure decreases as altitude increases. Because of this reduced air pressure, the volume of air a person inhales contains fewer oxygen molecules, which makes the body work harder to breathe. Although it may vary, altitude levels of 5,000 feet and above may lead to changes in breathing, including shortness of breath.

Environmental pollutants: Breathing in certain fumes, pollutants, and chemicals can irritate the lungs. Once irritation occurs, narrowing of the airways and inflammation may develop, leading to shortness of breath.

After considering some factors that may cause Dyspnea it is also important to note that in some instances, an individual may want to contact a doctor for shortness of breath. A person should consider contacting a doctor for shortness of breath if it occurs for unknown reasons or seems unrelated to their activities or fitness level.

A person should seek emergency medical treatment if they experience a sudden onset of shortness of breath or chest discomfort, pain, or pressure. Other symptoms that may be of concern are: shortness of breath when resting, shortness of breath that causes one to wake up while sleeping, shortness of breath after mild activities, fever, tightness in the throat
wheezing or a barking cough

Treatment
Treatment for shortness of breath depends on the cause.
For example, when a medical condition causes shortness of breath, treatment will involve managing the underlying condition to reduce the symptoms.
Treatment may also include making certain behavioral changes, such as:
getting regular exercise, if possible
quitting smoking, if applicable
reducing exposure to pollutants

Prevention
Prevention like it is always said is better than cure, however It is not always possible to prevent all instances of shortness of breath. But there are a few things that may help, including:
controlling indoor air pollution to reduce lung irritation
gradually increasing altitude to allow the body to adjust over time
managing any medical conditions that lead to fluid on the lungs
getting regular exercise, if possible, to prevent deconditioning
And also taking asthma and COPD medications when prescribed by experts.