# Evaluation of the Indoor Air Quality in Governmental Oversight Supermarkets (Co-Ops) in Kuwait
## 3 Results and Discussion  
### On-Site Measurements of Indoor Air Quality Indicators  
It is worth mentioning that the concentration averaging time in all the figures in this study is 15 min. It was found that the average duration visits to the Co-Ops was 15 to 45 min. Figure 2 shows the CO\({}_{2}\) concentration for Co-Ops for spot 1, 2, and 3 in the morning, noon, and evening. The highest recorded CO\({}_{2}\) concentrations were in descending order for the evening, noon, and morning. In the morning, most of the observed data points were within the threshold limit, whereas in the evening period, most of the recorded readings were highly above the threshold value, except for Co-Op 3. The \(\times\) sign in the box plot refers to the mean value, while the \(\bullet\) sign refers to an outlier value (comparing to other values). This symbolism is true for all the box-plots of data in Figures 2-8 in this study. A trend was noticed with the CO\({}_{2}\) measurements: the CO\({}_{2}\) concentration in the evening was the highest, then at noon. Figure 3, which shows the results for Co-Op 1, S1, demonstrates this finding. This may refer to customer density. [PERSON] et al. [33] studied the CO\({}_{2}\) concentration in four shopping malls in China and found that CO\({}_{2}\) concentration was positively correlated with customer flow rate. Hence, CO\({}_{2}\) concentration in the evening for mall C was the highest, with a maximum value of 1050 ppm at 17:30 [33]. Figure 2: CO\({}_{2}\) concentration for all Co-Ops, spot S1, S2, and S3: (**a**) Morning; (**b**) Noon; (**c**) Evening. A comparison of the CO concentration findings for the morning, noon, and evening for all the Co-Ops, including all the spots, is shown in Figure 4.  
Figure 4: _Cont._  
Figure 3: CO\({}_{2}\) concentration for Co-Op 1, S1. Compared to the other spots, S1 at Co-Op 1 and S1 at Co-Op 3 show remarkable readings. In S1 at Co-Op 3, for instance, the mean value for the dataset passed the daily maximum exposure set by WHO. The mean of S1 at Co-Op 1 passed the upper limit value set by the Lithuania IAQ Regulations (the averaging period was not specified by the Lithuania IAQ Regulations). For the other spots, CO concentration ranged between 0.1 and 2 ppm. One possible source of CO in Co-Ops is automobiles crowded on the street passing by the Co-Op's entrance. The variation of hydrogen sulfide (H\({}_{2}\)S) concentration among Co-Ops and different spots for different periods is depicted in Figure 5.  
Figure 4: CO concentration for all the Co-Ops, spot S1, S2, and S3 for: (**a**) morning, (**b**) noon, and (**c**) evening. Figure 5 shows that the mean of four measurements exceeded the threshold limit set by CAAQS (averaging period of 1 h) and reached the fifth measurement Co-Op 1, S1 in the morning. Indeed, values of 0.07 and 0.08 of H2S concentration were reached at S1 (Co-Op 1) and S2 (Co-Op 1) respectively. Different indoor hydrogen sulfide concentrations were found in the literature. For example, [PERSON] et al. [34] found that the average value of hydrogen sulfide in a laboratory building was 5.7 ppm. [PERSON] and [PERSON] [35] documented that the average hydrogen sulfide concentration inside a museum was 0.002 ppm at afternoon. This difference is due the difference in the indoor environment. The VOC sensor, type PID, measures a very wide range of VOCs; hence, it can indicate the total VOCs (TVOCs). By multiplying the sensor concentration reading by the corresponding response factor (RF), the resulted required gas (specific compound of VOCs) can be obtained. The RF of benzene (C6H6) and styrene (C8H8) are 0.53 and 0.40, respectively, as stated in the manufacturer's technical notes. The RF values ranges from 0.40 to 11.0. Besides TVOCs, C6H6 and C8H8 were chosen for VOCs representations for two reasons. Firstly because a smaller RF means that the PID sensor is more sensitive to the compound, which is the case for these two compounds and secondly, because of their hazardous health impact on humans.