## 1 Introduction  
The coronavirus SARS-CoV-2 was first detected in the city of Wuhan, China, in December 2019, and a few months later (11 March 2020), WHO proclaimed it responsible for the COVID-19 pandemic.  
SARS-CoV-2 is transmitted by direct (person-to-person) or indirect contact (e.g., inhalation of respiratory droplets, aerosols produced by coughing and sneezing of infected persons) [1; 2].  
Indirect transmission can also occur when a person comes into contact with contaminated surfaces [2]. However, environmental spread of SARS-CoV-2 to humans via contaminated surfaces remains controversial. [3]. Some studies on the viability and resistance of the virus on surfaces [4; 5; 6] demonstrated that SARS-CoV-2 can remain infectious for days, while other authors reported that the risk of infection is relatively low [7; 8; 9]. Environmental surveillance for SARS-CoV-2 using surface swabs could demonstrate the stability of the virus in the environment and thus counteract the spread of COVID-19. Testing of environmental samples, such as wastewater and surface swabs, provides indirect evidence of the number of infected individuals shedding the virus [10; 11; 12; 13].  
Environmental monitoring has become a useful adjunct to clinical trials, in part because the molecular tests commonly used to detect SARS-CoV-2 RNA (RT-qPCR) are widely available and relatively inexpensive [14; 15]. Furthermore, environmental monitoring also avoids issues of informed consent, operational logistics, and fairness that can slow down or limit clinical trial programs [16; 17].  
In Italy, the start of the COVID-19 epidemic was in February 2020. A lockdown was immediately imposed, ordering the closure of all social and cultural centers, including schools and universities. [18]. Throughout the lockdown period, until the fourth wave of the epidemic (autumn 2021-spring 2022), university and scientific activities (e.g., lectures, seminars, exams, conferences) were carried out remotely in several Italian regions, such as Apulia.  
From March 2022, following an improvement in the pandemic situation, university teaching activities resumed in person, with the exception of people affected by chronic diseases and immunodression and subjects with SARS-CoV-2 infection. Several authors have studied surface contamination in hospital and community settings, including cultural centers, schools, and universities [3; 9; 19], but few studies refer to the post pandemic period and the resumption of face-to-face activities. Similarly, the resistance and viability of SARS-CoV-2 on surfaces and fomites via cell culture have been poorly assessed due to the limitations of low sensitivity and the availability of biosafety level 3 laboratories [3].  
In April 2022, the University of Bari \"Aldo Moro\", one of the largest universities in southern Italy, attended by students from all over the Apulia region, approved the project entitled \"The safe resumption of face-to-face teaching in the COVID-19 era: Precision Containment Strategies (SCOOP)\", as part of the HORIZON EUROPE SEEDS projects (D.R. n. 1333, 11 April 2022). This project focused on the environmental monitoring of SARS-CoV-2 in crowded environments such as universities, where environmental contamination and the associated risk of indirect transmission between staff, students, and multitouch surfaces can easily emerge.  
The aim of this study was (i) to evaluate the presence and viability of SARS-CoV-2 in university classrooms after the resumption of face-to-face teaching activities; (ii) to evaluate the influence of some parameters (e.g., type of surface, material, number of attending students, seasonality) on the viral presence; (iii) to compare positive environmental samples for virus against the trend of COVID-19 cases to identify an early warning system for disease cases.