Assessment of carbon monoxide concentration in indoor/outdoor air of Sarayan city, Khorasan Province of Iran.

Nowadays, air pollution by humans is considered a serious problem. One of the main sources of air pollution is carbon monoxide which is called the silent killer. With the increasing rate of population growth in Iran and subsequent acceleration of vehicle and fossil fuel usage, the mortality rate of carbon monoxide has increased. The aim of this study is assessment of the concentration of carbon monoxide in indoor and outdoor air of Sarayan city, Khorasan Province of Iran. In this descriptive-analytic study, the air condition of a residential area and outdoor environment of Sarayan city has been monitored for determining the carbon monoxide concentration during a 3-month period from January to March 2017. Overall, 25 stations with uniform distribution were located in the city. Fifty samples were taken monthly and by considering 3-month period, a total of 150 samples were gathered. The samples were taken in kitchens between 11 a.m. and 3 p.m., and by considering the respiratory height of the human body, the carbon monoxide meters (TES model, Taiwan) were placed at a height of 75-150 cm. The descriptive statistics were presented after entering data into SPSS-16, and, by applying Mann-Whitney and Kruskal-Wallis tests in the case of α = 0.05, the data were analyzed. The average concentrations of carbon monoxide in indoor and outdoor environments were 0.84 ± 3.21 ppm and 0.27 ± 0.92 ppm, respectively. The maximum carbon monoxide concentration in February in an outdoor environment was 6 ppm (station no. 4) and the least one was 0 ppm. In March, for an indoor area, the maximum carbon monoxide concentration was 41 pm for station no. 11. The indoor-to-outdoor (I-to-O) ratio in March was higher than other months, and in January, was less than others. The study reveals that the indoor and outdoor carbon monoxide indices of Sarayan city are at acceptable levels.