EVALUATION OF A PROFESSIONAL CLEANING SERVICE IN A CIVIL CONTEXT: MICROBIOLOGICAL AND ENVIRONMENTAL COMPARATIVE ANALYSIS BETWEEN TRADITIONAL AND “GREEN” METHODS

Abstract

Surface contamination represents one of the main routes for virus and bacterial diffusion due to the presence of saliva’s droplets, respiratory secretions, and viral particles which deposit on it. An optimal cleaning and disinfection protocol is fundamental to preserve a hygienic and disinfected surface in public areas, limiting, in this way, pathogens transmission. Nevertheless, cleaning and disinfection processes can lead to significant environmental impacts such as raw materials consumption, transportation of commodities and people, the end of life of the equipment, emissions, and waste production due to packaging. Moreover, cleaning and disinfection activities lead to the consumption of electric energy for water heating and for powering the cleaning equipment, contributing to the emission of greenhouse gasses. In Italy, Minimal Environmental Criteria (Criteri Minimi Ambientali, CAM), published on the Italian Official Journal on 01/29/2021, represent an important policy instrument to promote environmental sustainability in public and private tenders. Within the framework of the cleaning and disinfection sector, CAM can lead towards the adoption of products and processes with a low environmental impact, promoting more sustainable proceedings. In this work, a “GREEN” protocol, has been developed, according to CAM policies, and evaluated applying it in the context of civil cleaning services. The evaluation has been carried out both through a Life Cycle Assessment analysis (LCA) with an approach “from cradle to grave” and in terms of hygienic and microbiological parameters with the quantification of heterotrophs bacteria at 22°C and 37°C in 12 sampled surfaces at BL27 building of the Bovisa La Masa Campus in Politecnico of Milano. Each surface was sampled in triplicate before and after its disinfection. This location has been chosen as an example of civil environment as it comprises classrooms, connective spaces, services, offices, cafeterias, libraries and reading rooms and because it was representative for surface typologies, degree of dirt and for the frequency and methodologies used in civil cleaning worksites. Preliminarily, also the presence of pathogenic bacteria which are fecal contamination indicators has been assessed on each surface with the quantification of  E.coli and Clostridium perfringens.

The study has been carried out in a comparative way with respect to a more traditional cleaning protocol and it demonstrated the effectiveness of the “GREEN” protocol, appropriate to the intended use of the considered area. As there aren’t any standards or guidelines about the quantitative evaluation of microbial contamination found on surfaces, we considered as reference value the one used for restoration environments (80 UFC cm^-2) as the location object of the study does not present particular issues. In fact,  in almost all the samples we have taken from the 12 surfaces, the parameters relative to fecal contamination indicators were under the limit of detectability (1 CFU cm^-2), only in one of the three replicas of SUP1 (classroom floor), 1 CFU cm^-2 of C. perfringens  has been detected. The “GREEN” protocol guarantees a substantial reduction of the bacterial load and its maintenance under the value of 80 CFU cm^-2. Through the LCA analysis, this study has also assessed a reduction of 29 g of CO₂ per squared meter (18.4%) in the carbon footprint of the “GREEN” protocol respect to the traditional methodology. The value of this result can be even more appreciated if considering the entire scenario of application of the “GREEN” protocol, in fact the application of the aforementioned cleaning service in the whole pilot site would allow the abatement of 311 kg of emitted CO₂.