Table 1.
Study characteristics.
| Study characteristics | Studies (N=53), n (%) | Participants (N=55,284), n (%) | ||||
| Regions and countriesa | ||||||
|
|
North America | 30 (56.6) | 3524 (6.4) | |||
|
|
|
United States | 24 (45.3) | 2807 (5.1) | ||
|
|
|
Canada | 5 (9.4) | 697 (1.3) | ||
|
|
|
Mexico | 1 (1.9) | 20 (0) | ||
|
|
Asia | 11 (20.8) | 1226 (2.2) | |||
|
|
|
Hong Kong | 1 (1.9) | 740 (1.3) | ||
|
|
|
China | 3 (5.7) | 161 (0.3) | ||
|
|
|
India | 3 (5.7) | 141 (0.3) | ||
|
|
|
Japan | 2 (3.8) | 97 (0.2) | ||
|
|
|
Singapore | 2 (3.8) | 87 (0.2) | ||
|
|
Europe | 5 (9.4) | 94 (0.2) | |||
|
|
|
Belgium | 1 (1.9) | 39 (0.1) | ||
|
|
|
United Kingdom | 2 (3.8) | 33 (0.1) | ||
|
|
|
Germany | 1 (1.9) | 15 (0) | ||
|
|
|
Cyprus | 1 (1.9) | 7 (0) | ||
|
|
Oceania | 4 (7.5) | 597 (1.1) | |||
|
|
|
Australia | 4 (7.5) | 597 (1.1) | ||
|
|
Middle East | 3 (5.7) | 2192 (4) | |||
|
|
|
Qatar | 1 (1.9) | 2088 (3. 8) | ||
|
|
|
Israel | 1 (1.9) | 104 (0.2) | ||
|
|
|
Saudi Arabia | 1 (1.9) | 23 (0) | ||
|
|
South America | 0 (0.0) | 0 (0) | |||
|
|
Africa | 0 (0.0) | 0 (0) | |||
|
|
Countries not specified (68 countries: 42 high-income countries; 17 upper–middle-income countries; 9 lower–middle-income countries) | 1 (1.9) | 47,628 (86.2) | |||
| Study settinga,b | ||||||
|
|
Urban | 31 (58.5) | —c | |||
|
|
|
Outdoor | 9 (17.0) | — | ||
|
|
|
Indoor | 5 (9.4) | — | ||
|
|
|
Indoor and outdoor | 17 (32.1) | — | ||
|
|
Rural | 11 (20.8) | — | |||
|
|
|
Outdoor | 7 (13.2) | — | ||
|
|
|
Indoor | 1 (1.9) | — | ||
|
|
|
Indoor and outdoor | 3 (5.7) | — | ||
|
|
Climatic chamber or laboratory | 19 (35.8) | — | |||
| Study duration | ||||||
|
|
Cross-sectional data collection points (up to 4 hours each) | |||||
|
|
|
≤5 data collection points | 17 (32.1) | 496 (0.9) | ||
|
|
|
≥6 and ≤10 data collection points | 3 (5.7) | 174 (0.3) | ||
|
|
|
≥11 and ≤50 data collection points | 3 (5.7) | 116 (0.2) | ||
|
|
Continuous monitoring (at least 1 [work] day) | |||||
|
|
|
≤7 days | 16 (30.2) | 3614 (6.5) | ||
|
|
|
≤1 months | 6 (11.3) | 171 (0.3) | ||
|
|
|
≤6 months | 5 (9.4) | 542 (1) | ||
|
|
|
≤2 years | 3 (5.7) | 50,171 (90.8) | ||
| Study design | ||||||
|
|
Experimental crossover studyd | 7 (13.2) | 210 (0.4) | |||
|
|
Prospective cohort study | 20 (37.7) | 49,690 (89.9) | |||
|
|
Retrospective cohort study | 1 (1.9) | 104 (0.2) | |||
|
|
Prospective observational crossover studyd | 14 (26.4) | 5017 (9.1) | |||
|
|
Method comparison or evaluation study | 11 (20.8) | 263 (0.5) | |||
aMultiple characteristics may apply per study.
bInformation for study settings is not available for all study participants and therefore not summarized here as the number of participants per study setting.
cNot available.
dEach participant serves as their own control or comparison.