Exploratory study of the indoor and outdoor relationships and chemical compositions of particulate matter in urban households in Colombo

Air pollution associated with emissions of fine particulates (PM¹⁰ and PM^2.5) is becoming acute, especially in the urban environments of Sri Lanka during the last decade. Recent air quality data obtained from the monitoring stations located in Colombo Fort revealed that the average annual ambient PM¹⁰ concentrations in Colombo ranged between 72 and 82 μg/m³, exceeding the national ambient air quality PM¹⁰ standard of 50 μg/m³ and WHO air quality guideline of 20 μg/m³. This paper presents the chemical compositions of indoor and outdoor PM¹⁰ at selected locations in Colombo, Sri Lanka. Twelve-hour indoor/outdoor PM¹⁰ were collected simultaneously from six naturally ventilated roadside households from 13 March to 27 April 2010. Chemical compositions were obtained by using thermal optical reflectance method for carbonaceous compounds and ion chromatography method for water-soluble ions. The results show that indoor micro-environments were significantly affected by the infiltration of outdoor air in Sri Lanka, revealing that outdoor emission sources have significant effects on the indoor air quality. This study provides valuable information on chemical profile of particulates in Colombo which will definitely contribute to the formulation of environmental policy, especially on air pollution control in the future.