SHORT-TERM MONITORING OF INDOOR FORMALDEHYDE (HCHO) AND TOTAL VOLATILE ORGANIC COMPOUND (TVOC) CONCENTRATIONS ACROSS RESIDENTIAL MICROENVIRONMENTS USING A PORTABLE LOW-COST AIR QUALITY SENSOR IN BALLARI, KARNATAKA, INDIA

Indoor air quality is an important concern as people spend much of their time inside buildings and may be exposed to pollutants from various indoor activities. This study examined the hourly concentrations of formaldehyde (HCHO) and total volatile organic compounds (TVOC) in a residential building in Ballari, Karnataka, India. Monitoring was carried out in the living room, kitchen, and bedroom for 15 days during March and April 2025 using a portable low-cost air quality monitor. HCHO, TVOC, temperature, and relative humidity were recorded hourly between 06:00 and 23:00 h. The results showed noticeable differences in pollutant levels between the three indoor environments. The kitchen recorded the highest HCHO (0.199 mg/m³) and TVOC (0.826 mg/m³) concentrations, mainly during cooking and gas stove use. The living room showed moderate levels, with higher concentrations during evening hours, whereas the bedroom generally had lower and more stable concentrations. HCHO and TVOC showed similar variations, suggesting the influence of common indoor sources. Cooking, ventilation, and occupant activities were found to be important factors affecting indoor pollutant levels. The study demonstrates the usefulness of low-cost monitors for residential IAQ assessment and emphasizes the need for proper kitchen ventilation and adequate air exchange to reduce indoor pollutant exposure.