Table 2.
Indoor and outdoor PM2.5 concentrations and its possible sources from various schools
| Reference | Location | # Schools | Concentration range (μg/m3) |
Ventilation system | Findings | |
|---|---|---|---|---|---|---|
| Indoor | Outdoor | |||||
| This study | Northeast, USA | 32 | 0.8–16.9 | 3.3–16.6 | 17 natural, 3 central HVAC, 12 mixed | I/O PM2.5 = 0.8; Sources: Ca-rich material, road dust, sea salt, vehicles, biomass burning, regional. |
| Hochstetler et al. (2011) | Ohio, USA | 4 | 6.9–28.3 | 3.8–27.6 | 3 schools open windows | I/O PM2.5 = 0.5–2.8 |
| Keeler et al. (2002) | Michigan, USA | 2 | 6.5–16.4 | 11.6–20.6 | Opening windows, no air conditioning | I/O PM2.5 = 0.5–1.4 |
| Bozlaker et al. (2017) | Texas, USA | 1 | 2.3–4.1 | 13.4ⱡ | Mechanical | I/O PM2.5 = 0.2; Sources: soil & road dust, vehicular emissions, petroleum refining, oil combustion, coal combustion, vegetative burning, sea salt, ca-rich material, incineration, steel plant |
| Amato et al. (2014) | Barcelona, Spain | 39 | 7–105 | 1–192 | Natural | Sources: organic/ textile/ chalk, heavy oil, metallurgy, sulfate & organics, nitrate, traffic, road dust, mineral, sea salt |
| Jovanović et al. (2014) | Serbia | 1 | 26.9–63.9 | -- | Natural | I/O PM2.5 = 1.0 |
| Fromme et al. (2008) | Munich, Germany | 1 | 19.3–105.9 | 5.1–67.4 | Natural | Indoor PM consists mainly of crustal materials, detrition of the building materials and chalk |
| Canha et al. (2014) | Rural Portugal | 1 | 100ⱡ | -- | Natural | Sources: bakery industry, wood burning process/ soil re-suspension/ chalk use, crustal, and marine contributions |
| Almeida et al. (2011) | Lisbon, Portugal | 3 | 10ⱡ | 3 – 10 | Natural | Elemental composition suggested sources: crustal materials, detritions of the building materials and chalk |
| Zwoździak et al. (2013) | Wroclaw, Poland | 1 | 13.5–59.8 | 9.1–15.6 | Natural | I/O PM2.5 = 2.0 for winter, 4.1 for summer |
| Stranger et al. (2008) | Antwerp, Belgium | 27 | 26–129 | 12–148 | Opening windows | I/O PM2.5 = 1.3 |
| Borgini et al. (2011) | Milan, Italy | 3 | 79.4ⱡ | 77.9ⱡ | Natural | I/O PM2.5 = 1.0 |
| Janssen et al. (2001) | Netherlands | 24 | 7.7–52.8 | 5.2–60.8 | -- | I/O PM2.5 = 0.9 |
| Wichmann et al. (2010) | Stockholm, Sweden | 6 | 2.8–13.9 | 5.2–24.2 | Mechanical | I/O PM2.5 = 0.9 |
| Hou et al. (2015) | Beijing, China | 2 | 11 – 79 | 17 – 87 | Natural | I/O PM2.5 = 0.6 (closed), 0.9 (open) windows and doors |
| Xu et al. (2015) | Xi’an, China | 1 | 141.8ⱡ | 167.8ⱡ | Natural | I/O PM2.5 = 0.8; sources: coal combustion, motor vehicle exhaust, other primary sources, and secondary formation |
| Habil et al. (2013) | Agra, India | 10 | 71.3–90.1 | -- | Natural | I/O PM2.5 = 1.0 for winter, 1.2 for summer, 1.1 for monsoon; Sources: vehicle, soil, metal processes, wind-blown dust, industrial |
| Chithra and Nagendra (2012) | Chennai, India | 1 | 32–61 | -- | Natural | I/O PM2.5 = 1.4 ± 0.7 |
ⱡ
Mean concentration