Concentrations of Carbon Monoxide in Indoor and Outdoor Air of Residential Buildings

People spend more than 90 percent of their time in indoor environments. Indoor air pollution is responsible for more than 2. 2 million deaths per year worldwide. 769 Carbon Monoxide (CO) poisoning occur in Iran annually. The aims of this study were to measure CO concentrations in outdoor air due to traffic، compare the results with air quality standards، and determine indoor to outdoor ratio for CO concentration. Measurements were conducted over a period of one year (from winter 2007 to autumn 2008) at 11 selected stations within the city. A single probe gas detector was used for measuring CO concentrations in indoor and outdoor environments. Maximum CO concentrations in outdoor air for winter and summer were determined as 11 ppm (station 8، a commercial area) and 10 ppm (station 9، state office building area)، respectively. Minimum CO concentrations were determined at stations 3 (i. e. 4 ppm) and 1 (i. e. 4 ppm). Respective values for indoor to outdoor (I/O) ratios of CO concentration were from 0. 2 to 1. 6and from 0. 2 to 1 ppm for winter and summer. It is difficult to estimation indoor CO levels through measuring its concentration in outdoor air. In all cases، CO concentrations in winter were higher than the summer and 1st floor were more polluted than the 4th floor.