In response to the indoor air-quality crisis in Delhi, especially during peak smog season, a team led by Ravi Kaushik—an aerosol scientist from Indian Institute of Technology Bombay—has developed AIRTH: a retrofit module that turns existing split air conditioners into efficient air purifiers. 

The innovation makes use of a HEPA-based “FILTRIX®” technology—tested across IIT Bombay, IIT Delhi and IIT Kanpur labs—that captures fine particles (down to 0.3 microns), allergens and even microbes, while ensuring minimal impact on AC cooling performance (a mere ~4 % drop) and reduced energy consumption (~13 % less).

What stands out is the affordability and ease of installation: priced under ₹3,000, the module simply mounts onto the indoor AC unit, eliminating the need to buy a separate bulky air purifier. The team claims over 25,000 AC units have already been upgraded, offering cleaner air in homes across Delhi.