## 1 Introduction
[16] revealed that geometric mean indoor NO\({}_{2}\) levels of 11.4 \(\mu\)g/m\({}^{3}\) (0.006 ppm) were associated with more frequent coughing and wheezing, as well as increased use of reliever medication during the day. This adds to the growing body of evidence emphasizing the adverse respiratory effects of indoor NO\({}_{2}\) exposure, highlighting the imperative for comprehensive air quality management both outdoors and within indoor spaces. Addressing indoor air pollution is increasingly crucial for public health initiatives, particularly in safeguarding vulnerable populations, including those with respiratory conditions such as asthma. Additionally, ozone poses environmental risks by causing oxidative damage to vegetation, including crops. The primary sources generally emit NO and NO\({}_{2}\), which we refer to as primary pollutants. Over time, NO oxidizes, producing secondary NO\({}_{2}\). Thus, in the vicinity of the source, the NO/NO\({}_{2}\) ratio is much higher than in regional background areas. Parking garages, often overlooked as critical microenvironments, play a pivotal role in exposing both drivers and workers to deleterious air emissions, contributing to the enduring adverse impacts of motor vehicle-related air pollution on human health and the environment [17; 18; 19]. A noteworthy global trend sees cities transitioning from conventional street parking to embracing biodiverse green spaces, with a marked preference for subterranean parking structures [20; 21]. The recently promulgated World Health Organization (WHO) guidelines underscore the paramount significance of air quality, estimating its toll at seven million premature deaths annually, with an additional loss of countless healthy life-years. Europe grapples with the grim reality that high NOx emissions from light-duty diesel vehicles (LDDVs) may be responsible for up to 10,000 premature deaths, particularly linked to PM2.5 and ozone formation [22]. Air pollution was responsible for 300.000 premature deaths in the EU27 in 2019 [23]. The primary provenance of atmospheric NOx lies in fossil fuels utilized for motor vehicles, power generation, and heating [24], augmented by natural sources such as forest fires and volcanic activity [25]. The combustion of gasoline and diesel engines within parking lots further contributes to the generation of nitrogen oxides through intricate chemical reactions between nitrogen (N\({}_{2}\)) and oxygen (O\({}_{2}\)) [26]. Recent findings have provided indications that suboptimal air quality could be linked to heightened severity and mortality in COVID-19 cases. However, the precise contribution of potential confounding factors at both individual and area levels to these observed variations remains uncertain. This underscores the need for comprehensive investigations to better understand the complex interplay between air quality and COVID-19 outcomes, considering various influencing variables that may impact the association [27]. Globally, endeavors to curtail NOx levels have given rise to initiatives ranging from the conception of car-free cities to reducing vehicular traffic for diverse reasons [28; 29]. In recent years, there has been a notable decline in NO (nitric oxide) and NO\({}_{2}\) (nitrogen dioxide) emissions from car exhaust, marking a positive trend in addressing air quality concerns. This reduction is attributed to the implementation of various techniques aimed at curbing nitrogen oxide emissions, particularly from diesel engines. Among these strategies is the utilization of Exhaust Gas Recirculation (EGR), a method that lowers combustion temperature by reintroducing cooled exhaust gas into the combustion chamber, thereby limiting the available oxygen for combustion. Additionally, after-treatment devices such as Selective Catalytic Reduction (SCR) and Lean NOx Traps (LNT) play a crucial role in causing chemical reactions to reduce NOx emissions.