Exposure reduction
N95 vs surgical mask: filtration is only half the story.
For particle exposure, a respirator works by combining filter performance with a close facial seal. A loose-fitting surgical or disposable mask can let substantial air bypass the filter around the edges.
Particulate respirator
N95-class concept
- • Designed to filter airborne particles to a defined standard.
- • Tight facial fit is central to real-world performance.
- • Air should preferentially pass through the filter material rather than leak around the edges.
Surgical / loose disposable mask
Barrier ≠ respirator
- • Useful for functions such as splash/droplet barrier and source control depending on the product.
- • Loose fit means air and small particles can leak around the edges.
- • It should not be treated as equivalent to a well-fitting particulate respirator for pollution exposure.
Fit check intuition
The best filter cannot help air that never goes through it.
Nose bridge
Shape the respirator so obvious gaps around the nose are minimized.
Cheeks / chin
Large side or chin gaps allow unfiltered air to bypass the material.
Facial hair
Hair crossing the sealing surface can interfere with a tight seal.
Important limit
A normal N95 particulate respirator does not protect against harmful gases or vapours.
Delhi air pollution is a mixture. A particulate respirator can reduce inhaled particles when it fits well, but that does not mean it removes gases such as ozone, carbon monoxide or nitrogen dioxide.
Primary reference
CDC/NIOSH — Community Respirators and Masks ↗Keep learning
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