Volatile organic compounds (VOCs) cause ill health. Increase in their concentration increases the occurrence of ill health among the room occupants. It is therefore important to monitor their concentrations in the indoor environments. Relative humidity affects the accuracy of the measured concentrations of VOCs and therefore it is important to dry the air samples. Some of the drying agents may react with the VOCs affecting the accuracy of the results. This study therefore sought to establish whether calcium chloride absorbs significant amount of VOCs when used as a drying agent. Three schools were purposefully selected based on the whiteboard ink that they used as well as their closeness to Egerton University where the analysis was carried out. The classrooms in the schools were randomly selected for air sampling. Air temperature, relative humidity and carbon dioxide concentration were read directly using AZ-0004 carbon dioxide sensor. Two air samples in each of the classrooms were collected actively using polythene bags. Anhydrous calcium chloride was placed in one of the polythene bags at the site of air collection. The samples were analyzed by use of gas chromatography. The amount of water vapour in the air sample was calculated based on the relative humidity, temperature and pressure. Pure water was used as an external standard for water vapour in the air sample. The results show that the absorption of the VOCs by calcium chloride ranged from 19.5% to 72.7% with an average absorption of 51.4%. This study concludes that a lot of VOCs are absorbed by calcium chloride when used as a drying agent. It recommends further study to establish the exact group of compounds which are absorbed by calcium chloride with an aim of establishing the use of calcium chloride as a scavenger for the indoor VOCs.
Keywords: Calcium chloride, Relative Humidity, Volatile Organic Compounds