Real-Time Measurements of Indoor–Outdoor Exchange of Gaseous and Particulate Atmospheric Pollutants in an Urban Area

Air pollution is one of the greatest environmental risks to health, causing millions deaths and deleterious health effects worldwide, especially in urban areas where citizens are exposed high ambient levels pollutants, also influencing indoor air quality (IAQ). Many sources fairly obvious well known, but contribution outside still leads significant uncertainties, particular influence that variables have on outdoor/indoor pollutant exchange mechanisms. This a critical aspect consider IAQ studies. In this respect, an experimental study was performed at public site such as university classroom during non-academic period Madrid city. includes two field campaigns, summer (2021) winter (2020), instruments for measuring gases particle pollutants simultaneously measured outdoor real-time concentrations. aimed investigate dynamic variations indoor/outdoor (I/O) ratios terms conditions (meteorology, turbulence quality) features (human presence or natural ventilation). The results show I/O ratio pollutant-dependent. sense, infiltration capacity higher gaseous compounds, case particles, it depends size, with smaller particles (<PM2.5). Additionally, under specific situations atmospheric stability, concentrations derived from traffic tend accumulate room, keeping background These decreased when room ventilation produced well-ventilated (high wind speed) external conditions. suggests meteorology parameters played key role by enhancing dispersion accumulation pollutants. obtained highlight number involved and, consequently, how complex its is. Thus, knowledge these factors understanding behavior controlling human exposure environments.