Asthma: Symptoms, Causes, Diagnosis, Treatment & Prevention Guide

Asthma is one of the most common chronic respiratory conditions worldwide, and Bangladesh's air quality crisis has made it an increasingly urgent public health concern. In 2023, Bangladesh was ranked the most polluted country globally, with an annual average PM2.5 concentration of 79.9 micrograms per cubic meter — more than double the national safety standard and roughly 16 times the World Health Organization's guideline of 5 micrograms per cubic meter. In cities like Dhaka, Chattogram, and Khulna, fine particulate levels regularly exceed WHO guidelines by 8 to 18 times. Research using the WHO PEN (Package of Essential Noncommunicable Disease Interventions) protocol found that self-reported asthma affects about 4.2% of Bangladesh's adult rural population, rising to 8.4% among people over 60. This guide covers what asthma actually is, how it is properly diagnosed, how it differs from similar conditions, and how it should be managed at every stage of life.

What Is Asthma and What Causes It?

Asthma is a chronic inflammatory disease of the airways. In people with asthma, the airway lining becomes persistently inflamed and hyper-reactive, so that triggers cause the muscles around the airways to tighten (bronchoconstriction), the lining to swell, and extra mucus to be produced. Together, these narrow the airway and make breathing difficult. Unlike some structural lung diseases, this airflow obstruction is typically reversible — either on its own or with medication — which is a key feature used in diagnosis.

Asthma does not have one single cause. It results from a combination of genetic and environmental factors:

• Genetics and family history: Having a parent or sibling with asthma meaningfully raises risk; studies show self-reported asthma is far more common among people with a family history of the disease.
• Air pollution: Fine particulate matter (PM2.5) from brick kilns, vehicle exhaust, industrial emissions, and seasonal biomass burning is a well-documented trigger and driver of asthma and COPD exacerbations in Bangladesh.
• Indoor allergens: Dust mites, mold, cockroach droppings, and pet dander.
• Tobacco smoke: Both active smoking and secondhand smoke exposure, especially in early childhood.
• Respiratory infections: Frequent viral infections in early childhood are linked to asthma development.
• Occupational and environmental exposures: Cooking smoke from biomass fuels, chemical fumes, and dust in certain workplaces.
• Other triggers: Cold air, strong odors, physical exertion, and emotional stress can provoke symptoms in people who already have asthma.

Recognizing the Symptoms

Asthma symptoms typically come and go in episodes rather than staying constant, and they often worsen at night, early in the morning, or after exposure to a trigger. Common symptoms include:

• Wheezing — a whistling sound when breathing, especially on exhaling
• Shortness of breath or breathlessness, even with mild exertion
• A feeling of tightness or pressure in the chest
• Persistent coughing, particularly at night or early morning, that may or may not produce mucus
• Symptoms that flare with exercise, cold air, dust, smoke, or strong smells

In young children, symptoms can be harder to interpret because wheezing can also come from other causes, which is why diagnosis in this age group follows a stricter set of criteria (see below).

How Asthma Is Diagnosed

Diagnosis combines a person's symptom history with objective lung-function testing wherever possible.

Spirometry and the reversibility test

The gold-standard test is spirometry, which measures how much and how fast air can be exhaled. In someone with suspected asthma, doctors look for a significant improvement in FEV1 (the volume of air forced out in one second) after giving a bronchodilator — specifically, an increase of 12% or more, and at least 200 mL, is considered a positive reversibility test consistent with asthma. Where a methacholine challenge test is available, a drop in FEV1 of 20% or more after inhaling methacholine also supports an asthma diagnosis by demonstrating airway hyper-reactivity.

Diagnosis in young children (5 years and under)

Because spirometry is difficult to perform reliably in very young children, international guidelines (GINA) recommend that a diagnosis of asthma in this age group requires all three of the following: recurrent episodes of wheezing, no more likely alternative explanation for the symptoms, and a clear, timely clinical improvement with asthma medication. All three criteria should be present before labeling a young child as asthmatic.

Biomarkers and monitoring tools

For more difficult or severe cases, blood eosinophil count and fractional exhaled nitric oxide (FeNO) are increasingly used as biomarkers to support diagnosis, assess the type of airway inflammation, and guide treatment decisions, particularly in specialist settings. At home, a peak flow meter can help track day-to-day lung function and warn of worsening control, though it is less precise than spirometry and can be affected by technique.

Asthma vs. COPD: How to Tell Them Apart

Asthma and Chronic Obstructive Pulmonary Disease (COPD) can look similar — both cause breathlessness, wheezing, and cough — but the underlying mechanism and long-term outlook differ, so distinguishing them matters for treatment.

• Reversibility: In asthma, airway narrowing improves substantially with bronchodilators (FEV1 rises ≥12% and ≥200 mL). In COPD, the obstruction is largely fixed: the post-bronchodilator FEV1/FVC ratio stays below 70% and does not normalize.
• Typical patient profile: Asthma often begins in childhood or young adulthood and is linked to allergies; COPD typically develops after age 40, strongly associated with long-term smoking or heavy air-pollution/biomass-smoke exposure.
• Course: Asthma symptoms are episodic and can be symptom-free between flares; COPD tends to be more persistently progressive.

Because both conditions can also overlap in the same patient (sometimes called asthma-COPD overlap), a doctor's assessment with spirometry is the only reliable way to confirm which condition — or combination — is present.

Severity, Control, and Treatment Approach

Modern asthma treatment, following international (GINA) guidelines, is organized as a stepwise ladder of five treatment steps, escalating based on how well symptoms are controlled rather than treating every patient the same way.

• Inhaled corticosteroids (ICS) are the cornerstone of asthma control at every step, reducing the underlying airway inflammation rather than just relieving symptoms.
• One widely recommended approach uses a combination ICS-formoterol inhaler both for daily control and, importantly, as the reliever taken during symptoms — this single-inhaler strategy is intended to reduce reliance on quick-relief-only treatment and lower the risk of severe attacks.
• An alternative approach pairs a low-dose ICS controller with a short-acting beta-agonist (SABA) — such as salbutamol — used only as needed for symptom relief.
• For more severe or poorly controlled disease, doctors may add long-acting bronchodilators (such as formoterol or salmeterol), leukotriene receptor antagonists (such as montelukast), or, in select cases, biologic therapies guided by blood eosinophil count.

In Bangladesh, commonly available asthma medicines include salbutamol (quick-relief inhaler), inhaled corticosteroids such as budesonide and beclomethasone, combination inhalers containing formoterol, and oral leukotriene blockers like montelukast — all of which should only be used under medical guidance and adjusted based on symptom control, never self-escalated without follow-up.

Correct Inhaler Use and Home Management

A large part of poor asthma control comes down to technique, not the medicine itself. Studies show that only about 8% to 22% of children use their inhalers correctly without training — a gap that directly undermines treatment. Using a spacer device with a metered-dose inhaler substantially improves how much medicine actually reaches the lungs, and repeated, hands-on technique checks at follow-up visits are strongly recommended, especially for children and elderly patients.

There is also a common myth that nebulizers are inherently more effective than inhalers. In fact, when used correctly, a metered-dose inhaler with a spacer delivers bronchodilator medication just as effectively as a nebulizer for most patients. Nebulizers remain useful for very young children, people who cannot coordinate inhaler technique, or during a severe attack in a clinical setting — but they are a delivery method, not a cure, and do not replace a proper daily controller regimen.

A written asthma action plan — agreed with a doctor — helps patients recognize early warning signs, know when to step up reliever use, and know when to seek urgent care.

When to Seek Emergency Care

Most asthma flares can be managed at home with a reliever inhaler, but certain signs indicate a medical emergency and require immediate hospital care:

• Severe breathlessness that prevents speaking in full sentences
• Lips or fingertips turning bluish or grey
• Visible use of neck or chest muscles to breathe, or the chest appearing to suck inward with each breath
• Little or no relief after using a reliever inhaler as directed
• Rapidly worsening peak flow readings or a peak flow far below the person's personal best
• Extreme fatigue, confusion, or drowsiness during an attack

Any of these warrants emergency medical attention without delay — asthma attacks can become life-threatening quickly if untreated.

Special Considerations

Children

Because wheezing in early childhood has many causes besides asthma, diagnosis should follow the strict criteria noted above rather than being assumed from a single episode. Ongoing, repeated education on inhaler technique — for both the child and caregivers — is essential, since correct technique tends to decline without reinforcement.

Pregnancy

Asthma symptoms worsen in roughly 40% of pregnant women, particularly those with obesity, multiple previous pregnancies, exacerbations before becoming pregnant, or poorly controlled asthma going into pregnancy. Reassuringly, the standard controller and reliever medications — including inhaled corticosteroids and short-acting beta-agonists like salbutamol — are considered safe throughout pregnancy, and studies have not found an increased risk of birth defects with albuterol/salbutamol use. Importantly, uncontrolled asthma poses a greater risk to both mother and baby than properly managed treatment does, so medication should never be stopped without medical advice.

Older Adults

Asthma prevalence rises sharply with age, reaching an estimated 8.4% among adults over 60 in Bangladeshi rural population data. In this group, asthma is often complicated by coexisting heart or lung disease, which can mask or mimic symptoms, making a doctor's evaluation and spirometry particularly important for accurate diagnosis and safe medication choices.

Bangladesh's Health System Response

Bangladesh's Directorate General of Health Services (DGHS) established a dedicated Non-Communicable Disease (NCD) Control unit in 2011, and the country has since set up NCD corners at the upazila (sub-district) level offering screening and basic care for chronic respiratory diseases like asthma and COPD alongside diabetes and cardiovascular disease. However, significant gaps remain: access to consistent respiratory care, essential medicine supply, and trained staff is markedly weaker outside Dhaka and other major cities, meaning many rural patients still face real barriers to timely diagnosis and ongoing treatment.

Prevention and Long-Term Control

• Reduce exposure to air pollution where possible — limit outdoor activity on high-pollution days, and use masks in heavy traffic or dusty environments.
• Avoid biomass cooking smoke indoors; ensure adequate ventilation if solid fuels must be used for cooking.
• Eliminate tobacco smoke exposure, both active smoking and secondhand smoke, especially around children.
• Control indoor allergens — regular cleaning, dust-mite-proof bedding covers, and moisture control to prevent mold.
• Stay current with vaccinations, including annual influenza vaccination, since respiratory infections are common asthma triggers.
• Take controller medication consistently even when feeling well — inhaled corticosteroids work by preventing inflammation, not just treating symptoms after they start.
• Keep regular follow-up visits to reassess control and adjust the treatment step up or down as needed, rather than only seeking care during an attack.

Asthma cannot currently be cured, but with an accurate diagnosis, the right stepwise treatment, correct inhaler technique, and attention to environmental triggers — a particularly important factor in Bangladesh's polluted air — the great majority of people with asthma can lead active, symptom-controlled lives. Anyone with recurring breathlessness, wheeze, or nighttime cough should see a doctor for proper evaluation rather than self-treating with over-the-counter remedies.

Sources: Global Initiative for Asthma (GINA) 2025 Strategy Report, World Health Organization (WHO) air quality guidelines, Directorate General of Health Services (DGHS) Bangladesh, and peer-reviewed studies on asthma prevalence and air pollution in Bangladesh.