Formaldehyde monitoring in office buildings located in tropical climates of India

Abstract

Indoor air pollution is a result of complex phenomenon that occurs due to constantly changing interaction of various indoor and outdoor environmental factors. Volatile Organic Compounds (VOCs) are the major pollutants in air conditioned indoors, perhaps having a large subset of hazardous compounds. In this study, formaldehyde (HCHO) was monitored at 30 minute interval using portable photoelectric absorptiometric sensors along with comfort parameters like air temperature, relative humidity and air flow rate at six newly constructed or renovated office buildings located in composite, temperate and warm-humid climatic zones (in various parts of India). Results show that formaldehyde emissions exceeded the limits suggested by LEED guidelines (27 ppb) in all the buildings except in the ones where low emitting green interiors were used. Furniture and interior decorative work were found to be the primary sources of formaldehyde emission than other parameters. A logarithmic relationship (R2=0.65) was established between HCHO and respective age of the building/refurbished time. The analysis also presents that in a scenario of green interiors (low HCHO concentration) and the humidity levels above 60%, the trend of HCHO concentration with indoor moisture exhibits certain time delays in reaching equilibrium due to slow conditioning of HCHO molecules and indoor moisture. The study provides a rational analysis on HCHO emissions in Indian office buildings, which is important to understand possible sources and their effects on HCHO concentration in office indoors. The study data helps to implement required measures to control indoor humidity levels or necessary HCHO mitigation strategies during design and operation process of the air-conditioned office buildings.