Author(s)

MARCO RAGAZZI, ROSSANO ALBATICI, MARCO SCHIAVON, NAVARRO FERRONATO, VINCENZO TORRETTA

Abstract

Carbon dioxide (CO₂) is a known global pollutant and is responsible for the global warming that the planet has been experiencing for the last few decades. On a local scale, outdoor CO₂ does not pose any risk for the environment and humans. Risks are usually far from involving human beings in the majority of indoor environments, although high CO₂ concentrations may entail temporary adverse effects that are similar to the typical symptoms of the so-called “sick-building syndrome”. Such effects become even more important on workplaces or at school/university, since high CO₂ levels may negatively influence the productivity and the learning capability of individuals. To understand the magnitude of the problem, a monitoring campaign was carried out in four classrooms and in a library of a university in northern Italy. Three of the classrooms under observation were not equipped with an air extraction system. The CO₂ concentration was monitored with low-cost non-dispersive infrared digital sensors in two periods of the year: between February and March and at the end of May. During those periods, the number of occupants, temperature and relative humidity were also monitored, as well as any opening of the windows (where available). The results showed that, where automatic air extraction is not available, CO₂ concentrations can exceed 5,000 ppm. In general, the lower the ratio between the room volume and the number of occupants, the higher the concentrations achieved. The installation of lowcost sensors might prove useful to prevent the negative effects from the exposure to high CO₂ levels and help achieve more sustainable conditions in indoor spaces, since the sensors could inform lecturers and students on the need for opening doors and/or windows when air extraction is not provided.

Keywords

carbon dioxide, indoor air quality, comfort, exposure, sustainability, ventilation, air quality monitoring