Most of us now check the AQI before stepping out. A green or yellow number feels like permission to breathe easy. But the number on your phone is built around a handful of measured pollutants, and in practice it is driven largely by PM2.5. The air you actually breathe carries far more than that.
What the AQI actually shows
The Air Quality Index turns the concentration of a few monitored pollutants into one easy number. In Indian cities that number is usually dominated by PM2.5: fine particles 2.5 micrometres across or smaller, small enough to travel deep into the lungs.
PM2.5 is a useful warning sign. It is not a complete picture. The World Health Organization’s 2021 guideline for PM2.5 is an annual average of just 5 µg/m³, and many Indian cities live at many times that level for most of the year. Even so, PM2.5 is only one pollutant out of thousands.
The real mixture you breathe
Air pollution is a complex mixture of physical, chemical and biological substances. Alongside PM10, PM2.5 and ultrafine particles, it includes:
- Gaseous pollutants such as ozone, nitrogen dioxide, sulphur dioxide and carbon monoxide
- Volatile organic compounds (VOCs) from fuels, paints, cleaners and even plants
- Heavy metals such as lead, mercury and arsenic, carried on fine particles
- Biological contaminants (bioaerosols) such as bacteria, viruses, mould spores and pollen
- Persistent organic pollutants, PFAS and microplastics that stay in the environment, and the body, for years
Pollutants made in the air itself
Not every pollutant comes out of a chimney or exhaust pipe. Secondary pollutants form in the atmosphere when primary pollutants react with each other and with sunlight. Ground-level ozone forms when nitrogen oxides and VOCs react in sunlight. Secondary organic aerosols form when ozone reacts with compounds released by plants and other sources.
This is why pollution in India is not only a matter of dust, vehicles and stubble burning. It is chemistry, and it continues every day of the year.
Indoors is not automatically safer
Walls and windows do not stop fine particles and gases. Microscopic pollutants leak into every building through gaps around doors, windows, vents and joints. Inside, they mix with indoor sources: cooking, incense, cleaning products, furniture and cosmetics. The result is that indoor air in Indian homes is often as polluted as the air outside, and sometimes worse.
- The AQI number is driven mainly by PM2.5, one pollutant among thousands.
- Gases, VOCs, heavy metals, bioaerosols and microplastics are part of the same air.
- Pollutants also form in the air itself through chemical reactions.
- Ordinary rooms do not keep these pollutants out.
What this means for you
A single filter that targets one pollutant cannot clean a mixture this varied. Clean air at home needs three things to work together: isolation from the polluted air outside, systemic filtration that handles particles, gases and biological contaminants, and sufficient airflow so that filtered air reaches every corner.
To understand the full range of pollutants, explore the types of air pollutants and the reasons for toxic air in India. To see how the AIRSHIP brings isolation, filtration and pressurisation together, read The Need for AIRSHIP.
This article is for general information. The AIRSHIP is not a medical device and does not treat or cure any disease.
Want to know how the AIRSHIP creates a pollution-free space at home?
Arrange your exclusive consultation
