The underpinning factors affecting the classroom air quality, thermal comfort and ventilation in 30 classrooms of primary schools in London

Sarkawt Hama; Prashant Kumar; Arvind Tiwari; Yan Wang; Paul F Linden

doi:10.1016/j.envres.2023.116863

The underpinning factors affecting the classroom air quality, thermal comfort and ventilation in 30 classrooms of primary schools in London

Environ Res. 2023 Nov 1;236(Pt 2):116863. doi: 10.1016/j.envres.2023.116863. Epub 2023 Aug 9.

Authors

Sarkawt Hama¹, Prashant Kumar², Arvind Tiwari³, Yan Wang⁴, Paul F Linden⁵

Affiliations

¹ Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom; Department of Chemistry, School of Science, University of Sulaimani, Sulaimani, Kurdistan Region, Iraq.
² Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom; Institute for Sustainability, University of Surrey, Guildford, GU2 7XH, Surrey, United Kingdom. Electronic address: p.kumar@surrey.ac.uk.
³ Global Centre for Clean Air Research (GCARE), School of Sustainability, Civil and Environmental Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom.
⁴ UCL Institute for Environmental Design and Engineering, London, United Kingdom.
⁵ Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, United Kingdom.

PMID: 37567379
DOI: 10.1016/j.envres.2023.116863

Abstract

The health and academic performance of children are significantly impacted by air quality in classrooms. However, there is a lack of understanding of the relationship between classroom air pollutants and contextual factors such as physical characteristics of the classroom, ventilation and occupancy. We monitored concentrations of particulate matter (PM), CO₂ and thermal comfort (relative humidity and temperature) across five schools in London. Results were compared between occupied and unoccupied hours to assess the impact of occupants and their activities, different floor coverings and the locations of the classrooms. In-classroom CO₂ concentrations varied between 500 and 1500 ppm during occupancy; average CO₂ (955 ± 365 ppm) during occupancy was ∼150% higher than non-occupancy. Average PM₁₀ (23 ± 15 μgm^-3), PM_2.5 (10 ± 4 μgm^-3) and PM₁ (6 ± 3 μg m^-3) during the occupancy were 230, 125 and 120% higher than non-occupancy. Average RH (29 ± 6%) was below the 40-60% comfort range in all classrooms. Average temperature (24 ± 2 °C) was >23 °C in 60% of classrooms. Reduction in PM₁₀ concentration (50%) by dual ventilation (mechanical + natural) was higher than for PM_2.5 (40%) and PM₁ (33%) compared with natural ventilation (door + window). PM₁₀ was higher in classrooms with wooden (33 ± 19 μg m^-3) and vinyl (25 ± 20 μgm^-3) floors compared with carpet (17 ± 12 μgm^-3). Air change rate (ACH) and CO₂ did not vary appreciably between the different floor levels and types. PM_2.5/PM₁₀ was influenced by different occupancy periods; highest value (∼0.87) was during non-occupancy compared with occupancy (∼0.56). Classrooms located on the ground floor had PM_2.5/PM₁₀ > 0.5, indicating an outdoor PM_2.5 ingress compared with those located on the first and third floors (<0.5). The large-volume (>300 m³) classroom showed ∼33% lower ACH compared with small-volume (100-200 m³). These findings provide guidance for taking appropriate measures to improve classroom air quality.

Keywords: CO(2); In-classroom air quality; Particulate matter; Thermal comfort; Ventilation.