The Importance of In-Depth Lung Health Screening in the Age of Pollution

• In the lungs of healthy individuals or non-smokers, there may be cells harboring hidden gene mutations. Continuous exposure to pollution stimulates lung immune cells to release inflammatory substances that trigger these mutated cells to divide abnormally, eventually progressing to lung cancer.
• The effects of pollution gradually alter the lung's structure and function, such as damaging the alveolar walls and gas exchange areas and causing fibrosis in lung tissue. Early stages usually show no symptoms, and standard tests like chest X-rays often fail to detect these abnormalities.
• In-depth lung health screening means comprehensive lung care during the pollution era to identify abnormalities early, increasing the chance of full recovery, reducing permanent damage, and preserving long-term quality of life.

Today, lung health is threatened by more than just cigarette smoke.

Air pollution, especially fine particulate matter (PM2.5), toxic gases, volatile organic compounds (VOCs), and microplastics, has become a primary risk factor affecting the general population, including non-smokers.

The incidence of chronic lung diseases and lung cancer among non-smokers is steadily rising and is not a coincidence.

Epidemiological and molecular biological evidence over the past decade consistently confirms that "air pollution is not just a symptom trigger but accelerates disease processes at structural and genetic levels in the lungs."

How pollution damages the lungs: from cellular level to cancer.

Pollutant particles and gases can bypass the upper airway filters, directly entering the distal bronchi and alveoli. When accumulated in lung tissue, they cause:

• continuous cellular inflammation,
• oxidative stress and free radical generation,
• damage to DNA, proteins, and lung cell structures.

Global research shows pollution acts as a “tumor promoter,” not merely a direct mutagen.

In normal or non-smoking lungs, cells may already harbor critical gene mutations such as EGFR or KRAS that accumulate with age.
Normally, these cells remain “dormant” and harmless, but continuous pollution exposure activates lung immune cells, especially macrophages, to release inflammatory agents like Interleukin-1β (IL-1β). This substance triggers dormant mutated cells to start abnormal division, eventually leading to lung cancer.

This mechanism clearly explains “lung cancer in non-smokers,” particularly in Asian populations where EGFR mutations are more prevalent than in Western populations.

Additionally, pollutants act synergistically, serving as “carriers” for heavy metals and toxins into the lungs, while VOCs and microplastics penetrate epithelial linings, provoking chronic inflammation and foreign body reactions—foundations for chronic lung diseases and long-term lung degeneration.

Lung damage: silent, easily missed, and irreversible.

Pollution effects usually develop gradually, altering lung structure and function at multiple levels, including:

• destruction of alveolar walls and gas exchange surfaces,
• development of interstitial lung fibrosis,
• abnormalities of small airways (small airway disease).

In early stages, most patients typically show no symptoms.
Standard tests such as chest X-rays, lung auscultation, or blood oxygen measurement often cannot detect these abnormalities. This underscores the crucial role of “in-depth lung health screening” in the pollution era.

Lung cancer screening with Low-Dose CT Chest (LDCT).

Low-Dose CT Chest (LDCT) is a low-radiation computed tomography scan providing detailed three-dimensional images far superior to standard chest X-rays, without compromising diagnostic capability.

LDCT advantages:

• detects small lesions, especially ground-glass or part-solid nodules, representing early-stage lung cancer that is potentially curable.
• non-invasive, no contrast dye injection, no surgery required.
• takes only a few minutes to perform.

Examples:Early-stage lung cancer lesions detectable by Low-Dose CT Chest (LDCT). Large studies show LDCT reduces lung cancer mortality by about 20% and detects early-stage lung cancer with over 93% sensitivity.

Pulmonary Function Tests: revealing lung degeneration before disease manifests.

Why Pulmonary Function Tests matter.

The lungs have a high functional reserve; patients can lose 30–40% of lung capacity without feeling breathless.
Pulmonary Function Tests assess lung and airway performance, detecting abnormalities “before symptoms appear,” especially small airway dysfunction where pollution damage begins.

What are Pulmonary Function Tests and how do they work?

Pulmonary Function Tests measure lung volume and airflow during inhalation and exhalation. The patient inhales fully then exhales forcefully and continuously into a Spirometer, which records data as a graph (Spirogram) and quantitative values.

This test requires patient cooperation and skilled technicians to ensure accurate and reliable results.

Key parameters to evaluate lung function.

FVC (Forced Vital Capacity).
Total air volume exhaled after a full inhalation.
Normal value is ≥ 80% of predicted.
Reduced in diseases with limited lung expansion, such as pulmonary fibrosis (restrictive lung disease).

FEV₁ (Forced Expiratory Volume in 1 second).
Air volume exhaled in the first second.
Normal value is ≥ 80% of predicted.
Decreased when airway obstruction is present.

FEV₁ / FVC (%).
Indicator of airway obstruction.
Normal value is ≥ 70%.

Types of lung abnormalities detected.

1. Obstructive – airway blockage (e.g., asthma, COPD).
2. Restrictive – reduced lung expansion (e.g., pulmonary fibrosis).
3. Combined – both obstructive and restrictive patterns.

Interpretation requires specialist physicians to ensure accuracy and appropriateness for each patient’s context.

Who should undergo in-depth lung health screening (LDCT + Pulmonary Function Tests)?

• Residents of large cities or areas with high PM2.5 levels.
• Individuals exposed to occupational pollution such as dust, smoke, or chemicals.
• Smokers or those exposed to secondhand smoke.
• Those with chronic cough or easy fatigue but normal chest X-rays.
• People who had COVID-19 and want to assess long-term lung function.
• Asymptomatic individuals seeking preventive screening.
• Those wanting baseline lung function data for future health monitoring.

Preparation before screening.

1. Low-Dose CT Chest.

• No fasting required.
• No contrast dye injection.
• Hold breath for about 15–20 seconds during the scan.
• The scan takes 5–10 minutes.

2. Pulmonary Function Tests.

• Wear comfortable, non-restrictive clothing.
• Avoid exercise at least 30 minutes before the test.
• Avoid smoking at least 1 hour before the test.
• Avoid alcohol for 4–6 hours before testing.
• Inhaler users should consult a doctor before testing.

3. Safety of the tests.

• Both LDCT and Pulmonary Function Tests are safe. Temporary dizziness, coughing, or breathlessness may occur during breathing tests. Report any abnormal symptoms immediately to staff.
• Individuals with conditions such as coughing blood, pneumothorax, or unstable heart disease should be evaluated by a physician before testing.

Summary: Lung health should not wait for symptoms.

• Low-Dose CT Chest (LDCT) reveals lung structure.
• Pulmonary Function Tests (PFT) assess lung function.

Together, these tests provide comprehensive lung care in the pollution era, detecting early abnormalities, increasing chances of cure, minimizing permanent damage, and preserving quality of life. Good lung health starts not with treatment after illness but with recognizing risk before disease becomes apparent.

Information courtesy of: Dr. Silawan Sathitrattanachaiwin, MD 54682, Pulmonary and Critical Care Specialist.Samitivej Sukhumvit Hospital.