Researchers from the Indian Institute of Technology Bombay (IIT Bombay) have identified a previously underexplored mechanism by which air pollution may worsen respiratory disease. The study suggests that under polluted conditions, lung mucus may behave in unexpected ways, potentially allowing soot particles to diffuse deeper into the respiratory tract.
The respiratory tract is lined with a thin layer of mucus that serves as a defense barrier. Normally:
Mucus traps dust, microbes, and pollutants.
Tiny hair-like structures called cilia move the mucus upward.
The trapped particles are expelled through coughing or swallowing.
This process, known as mucociliary clearance, is essential for maintaining lung health.
However, pollution exposure can alter mucus properties.
According to the IIT Bombay researchers, increased exposure to particulate matter (such as soot in urban smog) may stimulate excessive mucus production. Instead of uniformly protecting the airways, the mucus layer may form uneven, hump-like structures.
The researchers describe this phenomenon as a “mucus paradox”:
While mucus is meant to trap and remove pollutants,
Excess or structurally altered mucus may create microenvironments,
These may allow soot particles to diffuse through or accumulate in specific regions.
The study suggests that these mucus humps can potentially change airflow dynamics and particle deposition patterns in the lungs.
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Soot particles, commonly found in polluted urban air, are extremely small. Fine particulate matter (PM2.5) can penetrate deep into the bronchi and alveoli.
The IIT Bombay study indicates that:
Irregular mucus accumulation may disrupt uniform particle trapping.
Altered mucus rheology (flow properties) may reduce effective clearance.
Trapped pollutants may remain in contact with airway tissues longer.
This prolonged exposure can trigger inflammation, oxidative stress, and immune responses in airway cells.
Asthma is a chronic inflammatory airway disease characterized by:
Airway narrowing
Increased mucus production
Hyperresponsiveness to environmental triggers
In polluted environments, excess mucus combined with inhaled soot may exacerbate airway inflammation. The study suggests that in smog-affected cities such as Mumbai, individuals with asthma or other chronic respiratory conditions may be particularly vulnerable.
Pollution-induced changes in mucus properties may:
Increase airway obstruction
Impair clearance of inhaled particles
Prolong inflammatory responses
Mumbai and several other Indian cities experience seasonal spikes in air pollution. Fine particulate matter (PM2.5) levels frequently exceed recommended safety thresholds.
Understanding how mucus interacts with pollutants provides:
Insight into disease mechanisms
Better predictive models for pollution-related asthma flare-ups
Potential therapeutic targets to improve mucociliary clearance
Rather than viewing mucus solely as protective, the study highlights its complex and dynamic behavior under environmental stress.
Previous research has established that air pollution contributes to:
Asthma exacerbations
Chronic obstructive pulmonary disease (COPD)
Reduced lung function
Increased hospital admissions
The IIT Bombay findings add a biophysical dimension to this understanding, focusing on how mucus structure and mechanics may influence particle behavior within the respiratory tract.
Further research is expected to clarify how these findings translate into preventive strategies or targeted therapies for individuals living in high-pollution environments.
(Rh)