Comprehensive analysis of particulate matter, gaseous pollutants, and microbiological contamination in an international chain supermarket

Indoor environmental quality is of utmost importance since urban populations spend a large proportion of their life in confined spaces. Supermarkets offer a wide range of products and services that are prone to emitting several air pollutants. This study aimed to perform a comprehensive characterisation of the indoor and outdoor air quality in a multinational supermarket, encompassing not only criteria parameters but also unregulated pollutants of concern. Monitoring included measurements of comfort parameters, CO₂, multiple gaseous pollutants, particulate matter (PM₁₀) and bioburden. PM₁₀, volatile organic compounds (VOCs) and carbonyls were subject to chemical speciation. Globally, the supermarket presented CO₂, VOCs, and PM₁₀ values below the limits imposed by international regulations. The PM₁₀ concentration in the supermarket was 33.5 ± 23.2 μg/m³, and the indoor-to-outdoor PM₁₀ ratio was 1.76. Carbonaceous constituents represented PM₁₀ mass fractions of 21.6% indoors and 15.3% outdoors. Due to the use of stainless-steel utensils, flour and fermentation processes, the bakery proved to be a pollution hotspot, presenting the highest concentrations of PM₁₀ (73.1 ± 9.16 μg/m³), PM₁₀-bound elements (S, Cl, K, Ca, Ti, and Cr) and acetaldehyde (42.7 μg/m³). The maximum tetrachloroethylene level (130 μg/m³) was obtained in the cleaning products section. The highest values of colony-forming units of bacteria and fungi were recorded in the bakery, and fruit and vegetable section. The most prevalent fungal species was Penicillium sp., corresponding to 56.9% of the total colonies. In addition, other fungal species/sections with toxicological or pathogenic potential were detected (Aspergillus sections Aspergilli, Circumdati, Flavi, Mucor and Fusarium sp.).