Table 3.
Summary of best estimates and ranges of variables used in the nationwide representative School Building Archetype (SBA) model
| Parameter | Primary School Best-Estimate [Range] |
Secondary School Best-Estimate [Range] |
Reference |
|---|---|---|---|
| No. of educational institutions in US 2015–2016 | 88,665 | 26,986 | NCESa |
| No. of Index case/s | 1 | 1 | Assumption |
| Quanta generation rate (quanta / hour) | 1925 [1185–3345] | 2765 [1430–5140] | This Studyb |
| No. of enrolled students before outbreak | 513 [175–825] | 854 [245–1394] | NCESc |
| Infection period in school (day) | 3 [2–4] | 3 [2–4] | Literatured |
| Portion of unvaccinated students | 9% [8–10%] | 9% [8–10%] | CDCe |
| Portion of students with ≥2-dose vaccination | 91% [90–92%] | 91% [90–92%] | CDCe |
| No. of students in infector’s classroom | 21 [18–26] | 23 [18–30] | SASSf |
| Occupancy density of classroom (m2/person) | 4 [3–5] | 4 [3–5] | DOEg |
| Occupancy density of common area (m2/person) | 1.39 [1.04–1.74] | 1.39 [1.04–1.74] | DOEg |
| Average time spent in school (mins) | 400 [375–425] | 400 [375–425] | SASSh |
| Average time spent in common area (mins) | 20 [15–30] | 30 [20–45] | NFSMIi |
| Heating and cooling periods in US schools (day) | H: 200 & C: 90 | H: 200 & C: 90 | Assumptionj |
| HVAC system type | See Table 4 | See Table 4 | CBECSk |
| HVAC recirculation rate in classrooms (per hour) | 6.4 [3.3–8.5] | 6.4 [3.3–8.5] | Literaturel |
| Outdoor air ventilation in classrooms (L/s-person) | 6.7 [4.0–9.5] | 6.7 [4.0–9.5] | ASHRAEm, |
| Outdoor air ventilation in common area (L/s-person) | 4.9 [4.7–5.1] | 4.9 [4.7–5.1] | ASHRAEm |
| HVAC runtime for applicable systems | 1 | 1 | Assumption |
| Air filter removal efficiency (%) | 72% [44–86%] | 72% [44–86%] | NAFAn |
| Infiltration rate (1/h) | 0.31 [0.12–0.49] | 0.31 [0.12–0.49] | DOEg |
| Deposition rate of measles bio-aerosols (1/h) | 1.7 [1.0–2.7] | 1.7 [1.0–2.7] | Literatureo |
| Inhalation rate (m3/day) | 12.96 [11.34–14.53] | 15.53 [13.93–17.45] | EPAp |
aU.S. Department of Education, National Center for Education Statistics (NCES), [66]; Table 105.50 “Number of educational institutions, by level and control of institution: Selected years, 1980–81 through 2015–16”
bThe method explained in “Back-calculating quanta generation rate” Section and results are provided in “Estimates of quanta generation rate” Section
cU.S. Department of Education, NCES, [67]; Table 5 “Average student membership size of regular public elementary and secondary schools with membership, by instructional level, membership size of largest and smallest school, and state or jurisdiction: School year 2009–10”
dBased on existing epidemiological literature [68–70]
eCenters for Disease Control and Prevention (CDC) [71, 72]
fU.S. Department of Education, NCES, Schools and Staffing Survey (SASS) [73]; Table 7. “average class size in public primary, middle, and high schools is listed by classroom type and state in school year 2011–12”
gU.S. Department of Energy commercial reference building models of the national building stock, [48]; Appendix A
hU.S. Department of Education, NCES, SASS, [74]; “Average number of hours in the school day and average number of days in the school year for public schools, by state: 2007–08”
iNational Food Service Management Institute [75]
j200 days of heating season from October to mid-April and 90 days of cooling seasons in one school academic year
kU.S. Energy Information Administration, Commercial Buildings Energy Consumption Survey [76, 77]
lBased on Polidori et al. and Chan et al. studies [78, 79]
mThe American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 62.1–2016 Ventilation for Acceptable Indoor Air Quality (2016) [80]
nNational Air Filtration Association [81]
oBased on Azimi and Stephens study [54]
pU.S. EPA Exposures Factors Handbook [63]