Investigation of indoor air quality in shopping malls during summer in Western China using subjective survey and field measurement

- The subjective indoor air quality satisfaction levels in malls were around 3 (neutral).
- Stuffy odor had significant correlation with the overall odors and staff had noticeable SBS.
- Daily CO2 concentration increased when the customer 'rush' occurred.
- Underground floors had poorer indoor air quality than over-ground floors.
- Seriously polluted merchandise areas should be arranged near doors or vents.

Thermal parameters and concentrations of CO2, TVOC and formaldehyde were monitored in shopping malls in four western cities in China during summer. Simultaneously, questionnaire subjective surveys were carried out to investigate the indoor perception of air quality and Sick Building Syndrome (SBS) among staffs in the shopping malls. It was found that stuffy odor had significant correlation with the overall odors perception and staff in the shopping malls had noticeable SBS. Instrument measurement showed that mall C had higher pollution levels of TVOC, while formaldehyde concentrations were higher in mall X and L. Pollution level in the malls is influenced by many factors, and three factors (customer density, ventilation conditions, emission characteristic of merchandise) were discussed in the analysis of data from the four malls. For customer density, the concentrations of CO2 on weekends were higher than on weekdays. Daily CO2 concentration was positively correlated with customer flow rate, but there was no significant strong correlation between customer flow rate and TVOC/formaldehyde concentrations. Underground floors had poorer indoor air quality than over-ground because of lack of fresh air. As for the merchandise sections, the formaldehyde in the home textile section in mall X reached 1.15 mg/m3 with an over standard rate of 83.3% due to the new merchandise added. This paper makes a contribution to knowledge relating to the reasons for discomfort in shopping malls by contributing multiple investigations on contaminants together with information on human perception and the operation of air conditioning systems within the stores.