Medical education
Understand the air, not just the number.
Short, medically serious explainers for students and the public. Every page separates population-level evidence from individual diagnosis, and every mechanism is simplified without pretending biology is simple.
Particle size → lung deposition
What is PM2.5?
Why fine particles can reach the small airways and alveolar region, and how that links to respiratory and cardiovascular effects.
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Not just a bigger number
PM2.5 vs PM10
How fine and coarse particle fractions differ in size, deposition and what a monitor is actually reporting.
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Index ≠ concentration
AQI vs PM2.5
Why an AQI of 180 and PM2.5 of 80 µg/m³ are different kinds of numbers—and why two apps can disagree.
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Minute ventilation matters
Why exercise changes exposure
Running and basketball make you breathe more air per minute, changing particle dose even when the monitor reading is unchanged.
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Filtration + fit
N95 vs surgical mask
What particulate respirators can reduce, why facial seal matters, and what an N95 cannot remove from the air.
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Emissions × meteorology
Why Delhi gets worse in winter
Low wind, shallow mixing, regional transport and secondary aerosol formation help pollution accumulate near the surface.
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How to read these pages
Three different layers are kept separate.
Measurement
What was measured, where and over what averaging period?
Population evidence
What is associated with risk across groups and repeated exposure?
Personal decision
What is a sensible exposure-reduction choice today without pretending to diagnose you?