Table 1
Indoor bacterial and fungal concentrations in TB high-risk areas based on environmental parameters and other potential contributors
| Data for TB high-risk areas Median (IQR), unless indicated otherwise | Emergency department (n = 27) | TB ward (n = 47) | Bronchoscopy unit (n = 7) | TB clinic (n = 18) | All areas (n = 99) |
|---|---|---|---|---|---|
| Air change rate (h–1) | 6.0 (5.9–6.2) | 6.7 (6.1–7.3) | 7.0 (5.2–7.1) | 6.3 (5.2–7.0) | 6.2 (6.0–7.1) |
| Temperature (°C) | 25.6 (25.1–27.1) | 31.5 (29.1–32.0) | 24.6 (24.2–25.7) | 28.3 (26.3–30.7) | 27.9 (25.3–31.5) |
| Relative humidity (%) | 61.7 (60.0–63.7) | 66.7 (57.8–70.1) | 57.2 (53.8–66.3) | 68.2 (58.2–70.6) | 62.2 (57.8–70.0) |
| TB infection control score† | 24.0 (21.0–28.0) | 26.0 (22.0–28.0) | 21.0 (14.0–25.0) | 27.0 (23.8–28.0) | 26.0 (22.0–28.0) |
| Good level, frequency (%) | 23.0 (85.2) | 37.0 (78.7) | 4.0 (57.1) | 16.0 (88.9) | 80.0 (80.8) |
| Moderate level, frequency (%) | 4.0 (14.8) | 10.0 (21.3) | 3.0 (42.9) | 2.0 (11.1) | 19.0 (19.2) |
| Daily number of occupants in each area | 35.0 (15.0–60.0) | 7.0 (5.0–10.0) | 6.0 (5.0–15.0) | 20.0 (6.8–69.3) | 10.0 (5.0–30.0) |
| Daily number of active TB patient(s) in each area | – | 1.0 (1.0–1.0) | 1.0 (0.0–1.0) | 2.0 (1.0–7.0) | 1.0 (0.0–1.0) |
| Daily number of coughs by TB patient(s) not | 1.0 (0.0–1.0) | 3.0 (1.0–3.0) | – | 0.0 (0.0–1.0) | |
| wearing a protective mask in each area | |||||
| Ventilation system | |||||
| Natural ventilation, frequency (%) | 2.0 (7.4) | 37.0 (78.7) | – | 8.0 (44.4) | 47.0 (47.5) |
| Central-type air conditioner, frequency (%) | 12.0 (44.4) | – | – | 7.0 (38.9) | 19.0 (19.2) |
| Split-type air conditioner, frequency (%) | 13.0 (48.2) | 10.0 (21.3) | 7.0 (100.0) | 3.0 (16.7) | 33.0 (33.3) |
| Indoor airborne bacteria (cfu/m3)‡ | 691.0 ± 79.61 | 533.8 ± 132.50 | 567.9 ± 208.55 | 627.2 ± 124.60 | 596.1 ± 140.90 |
| Indoor airborne fungi (cfu/m3)‡ | 618.4 ± 108.03 | 464.7 ± 130.11 | 478.1 ± 178.01 | 539.7 ± 129.59 | 521.2 ± 142.20 |
[i] IQR, interquartile range; SD, standard deviation; TB, tuberculosis
†Good level = score 21–30 score; moderate level = score 11–20; poor level = score 0–10
‡cfu/m3: colony forming unit per cubic meter, mean ± SD
Figure 1
Concentrations of airborne bacteria and fungi, indoors (black bars) and outdoors (gray bars), in the emergency department, TB clinic, bronchoscopy unit, TB ward, and all areas (total). Error bars indicate SD from the mean (indicated above bars). SD, standard deviation; TB, tuberculosis
Figure 2
Size distributions of indoor airborne bacteria and fungi in emergency department, TB clinic, bronchoscopy unit, TB ward, and all areas (total). Median concentration (cfu/m3) at each Andersen impactor stage is indicated within the stacked bars. The stages are coded according to the key at the bottom of the Figure.
TB, tuberculosis
Table 2
Comparison of factors and indoor airborne bioaerosol concentration using linear regression
| Factor | Bacteria (cfu/m3)† | Fungi (cfu/m3)† | ||||
|---|---|---|---|---|---|---|
| B† | 95% CI (lower, upper) | P | Ba | 95% CI (lower, upper) | P | |
| Air change rate (h–1) | –71.30 | –87.54, –55.06 | <0.001*** | –71.64 | –88.09, –55.19 | <0.001*** |
| Temperature (°C) | –5.54 | –14.77, 3.69 | 0.24 | –4.36 | –13.70, 4.99 | 0.36 |
| Relative humidity (%) | 6.66 | 2.20, 11.12 | 0.004** | 6.07 | 1.53, 10.61 | 0.009** |
| TB infection control score | –3.39 | –10.48, 3.07 | 0.35 | –4.77 | –11.89, 2.36 | 0.19 |
| Daily number of patients with active TB (in each area) | –8.69 | –19.24, 1.85 | 0.11 | –9.03 | –19.66, 1.61 | 0.095 |
| Daily number of occupants in each area | 1.81 | 0.75, 2.87 | 0.001** | 1.82 | 0.75, 2.89 | 0.001** |
| Daily number of coughs by TB patients | 14.81 | 2.14, 27.47 | 0.022* | 10.40 | –2.56, 23.37 | 0.14 |
| (not wearing a protective mask) Department‡ | ||||||
| Emergency department | 130.49 | 72.77, 188.22 | <0.001*** | 133.59 | 75.50, 191.67 | <0.001*** |
| TB clinic and bronchoscopy unit | 19.42 | –45.48, 84.33 | 0.55 | 1.68 | –63.95, 67.30 | 0.96 |
| Ventilation system§ | ||||||
| Central-type air conditioner | 166.08 | 102.63, 229.53 | <0.001*** | 164.41 | 100.03, 228.78 | <0.001*** |
| Split-type air conditioner | –46.27 | –105.46, 12.93 | 0.12 | –53.67 | –113.17, 5.84 | 0.077 |
[i] †The mean indoor airborne bacteria and fungi (cfu/m3 = colony forming unit per cubic meter)
‡Emergency department (TB clinic and bronchoscopy unit, and TB ward = 0, Emergency department = 1), TB clinic and bronchoscopy unit
(Emergency department and TB ward = 0, TB clinic and bronchoscopy unit = 1)
§Central type air conditioner (natural ventilation and split type air conditioner = 0, central type air conditioner = 1), Split type air conditioner (natural ventilation and central type air conditioner = 0, split type air conditioner = 1)
*P < 0.05
**P < 0.01
***P < 0.001
Table 3
Comparison of factors and indoor airborne bioaerosol concentration using multiple linear regression
| Factors | Bacteria (cfu/m3)† | Fungi (cfu/m3)† | ||||
|---|---|---|---|---|---|---|
| B† | 95% CI (lower, upper) | P | B† | 95% CI (lower, upper) | P | |
| Air change rate (h–1) | –50.48 | –64.99, –35.97 | <0.001*** | –51.57 | –66.66, –36.48 | <0.001*** |
| Relative humidity (%) | 7.27 | 4.25, 10.29 | <0.001*** | 6.59 | 3.44, 9.73 | <0.001*** |
| Emergency department‡ | 65.05 | 21.99, 108.12 | 0.003** | 68.37 | 23.58, 113.15 | 0.003** |
| Central-type air conditioner§ | 113.90 | 63.60, 164.19 | 0.001** | 107.38 | 55.08, 159.68 | <0.001*** |
| Constant | 429.84 | 191.73, 667.96 | 0.001 | 405.80 | 158.18, 653.42 | 0.002 |
[i] †The mean indoor airborne bacteria and fungi (cfu/m3 = colony forming unit per cubic meter)
‡Emergency department (TB clinic and bronchoscopy unit, and TB ward = 0, Emergency department = 1), TB clinic and bronchoscopy unit
(Emergency department and TB ward = 0, TB clinic and bronchoscopy unit = 1)
§Central type air conditioner (natural ventilation and split type air conditioner = 0, central type air conditioner = 1), split type air conditioner (natural ventilation and central type air conditioner = 0, split type air conditioner = 1)
Model bacteria (cfu/m3) r2 = 0.636, model fungi (cfu/m3) r2 = 0.614
*P < 0.05
**P < 0.01