An air purifier hums in the corner, its display glowing blue. It feels like protection. But in an ordinary Indian home, a purifier is fighting a battle it cannot win, not because the filter is weak, but because of how air moves in and out of a room.
Infiltration beats filtration
Every building breathes. Outdoor air, and the pollution in it, constantly leaks in through gaps around doors and windows, ventilation openings, cable holes and the joints of walls and roofs. A simple rule decides whether a room can ever be clean:
If pollution enters your room faster than the purifier can filter it, the air stays contaminated. In cities where outdoor pollution is extreme for months at a time, that is the normal situation for most rooms.
Mixed air is not clean air
A conventional purifier works on air recirculation. It pulls in the room’s air, passes it through a filter and blows it back into the same room. That filtered air immediately mixes again with the polluted air already there and with the new pollution leaking in.
The result is an open-loop system: a constant blend of filtered and polluted air. Air can either be clean or polluted. There is no such thing as “somewhat clean”.
Leaky rooms cannot hold clean air
Clean rooms in hospitals and laboratories keep contaminants out by holding the air inside at a slightly higher pressure than outside, so air flows outwards, not in. That only works in a sealed space. It is not possible to positively pressurise a leaky room, let alone a whole house. In India, microscopic pollutants leak into all building structures.
Dead zones and the limits of one filter
Even inside a single room, filtered air does not reach everywhere. Corners, the space behind furniture and the area around a bed can become dead zones where pollutants build up because fresh, filtered air never arrives.
And the air itself is a mixture: particles, gases, VOCs, heavy metals and biological contaminants. A single filter designed mainly for particles cannot handle all of them.
- Pollution leaks into every room faster than most purifiers can remove it.
- Recirculation mixes filtered and polluted air, so the room is never truly clean.
- Leaky rooms cannot be pressurised to keep pollution out.
- One filter cannot handle the full mixture of pollutants in India’s air.
What actually works
Clean air needs three steps, in this order:
- Isolation: a sealed space built from non-permeable materials, so outside air cannot leak in.
- Systemic filtration: outside air drawn in through a multi-stage filtration unit that handles particles, gases and biological contaminants, then supplied inside.
- Pressurisation and airflow: a slight positive pressure that pushes air outwards, with enough air changes to replace the air inside continuously.
This is the principle of air filtration, not air recirculation, and it is how the AIRSHIP works. Its 7-stage filtration unit supplies filtered air into a sealed chamber, which holds a slight positive pressure so contaminants outside cannot enter. Read more in The Need for AIRSHIP.
The AIRSHIP is not a medical device and does not treat or cure any disease.
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