Indoor/indoor, indoor/outdoor ratios of CO and CO ₂ and their measured versus simulated concentrations in roadside eateries using coal-cookstoves

Indoor and outdoor concentrations of CO and CO ₂ were studied in two types of roadside eateries, e.g., two sides open (semi-open, n = 6) and closed from three sides (semi-closed, n = 2), both using coal-cookstoves. The 1-h time-weighted average (TWA) indoor CO concentrations ranged from 7.08 to 12.08 ppm in semi-open and 15.46 to 20.92 ppm in semi-closed types, respectively, whereas the corresponding 1-h TWA CO ₂ concentrations ranged from 546 to 645 ppm in semi-open and 649.9 to 810.4 ppm in semi-closed types. Notably, 1-h TWA indoor CO concentration exceeded the 6 ppm guideline value followed in Japan in all semi-open and semi-closed eateries but never exceeded WHO limit of 30.6 ppm. The indoor/outdoor (I/O) CO ratios ranged from 7 to 30 in semi-closed eateries and 2 to 19 in semi-open ones. On the other hand, I/O ratios of CO ₂ was much lower in both types of eateries viz. 1.2–2.78 and 1.14–1.98 for semi closed and semi open ones. Indoor CO and CO ₂ levels simulated by Gaussian dispersion algorithm were comparable to their estimated concentrations under ‘2 cookstoves burning 4 kilograms coal per hour’ scenario. High indoor CO and CO ₂ levels implied their build-up in eateries and underscored need for suitable interventions.