Indoor air pollution is a critical public health issue in densely populated countries such as Bangladesh, where PM2.5 levels indoors can reach 75–200 µg/m³, far exceeding the WHO safe limit of 5 µg/m³. Chronic exposure contributes to respiratory illnesses, allergies, skin conditions, and over 102,000 premature deaths annually, including 5,000 children under five. This research presents Project Nisshash, a clean-tech startup offering a modular dual-flow air purification system that actively exhausts polluted indoor air while supplying purified air. The system combines HEPA filtration for fine particulate matter, an activated carbon layer for smoke and chemical pollutants, and a dual-fan airflow architecture to prevent pollutant accumulation. Project Nisshash provides multiple product categories, including tabletop purifiers, room purifiers compatible with existing cooling systems, and kitchen purifiers that replace traditional exhausts while purifying incoming and outgoing air. The study evaluates the system’s feasibility, expected health impact, sustainability, and alignment with Sustainable Development Goals (SDG 3, 11, and 12). The findings demonstrate that Project Nisshash can significantly reduce indoor PM2.5 and allergen levels, improve overall indoor air quality, and provide a scalable, affordable solution for households, educational institutions, and small commercial spaces. This research contributes to the development of accessible, high-impact solutions to indoor air pollution in emerging economies. Keywords: Indoor Air Pollution, PM2.5, Air Purification, HEPA Filter, Activated Carbon, Dual-Flow Air System, Modular Design, Public Health, Bangladesh, SDG Alignment, Clean Technology