A resident of Delhi has captured attention online after building a DIY air purifier costing only ₹2,000 that reportedly lowered indoor air-quality index (AQI) from about 400 to 50 in just 15 minutes in a small room. According to a post on Reddit, the user constructed the device using a 150 mm exhaust fan (≈ ₹750), a HEPA filter (≈ ₹1,000), basic wiring and cardboard housing (≈ ₹200). The post claims that in a 12 × 12-foot room, the machine achieved this rapid drop in AQI at the lowest fan speed.

This comes amid worsening air pollution in Delhi and the NCR region during winter when AQI frequently enters the “severe” category. While air purifiers are known to help improve indoor air, the remarkable performance claimed by this DIY setup has generated considerable interest and discussion online. Observers note that while this may offer a low-cost solution for indoor air quality improvement, verification of measurements and long-term performance, maintenance of filters and room conditions remain important.