| Study |
| Mean Ratio | Source |
| South Western Nigeria | Bus drivers | 0.2768 | Present study |
| South Western Nigeria | Molue Bus drivers | 0.2822 | Ajayeoba [18] |
| South Western Nigeria | Taxi cab drivers | 0.2794 | Onawumi [8] |
| South Western Nigeria | Passengers in Busses | 0.2962 | Ismaila et al. [19] |
| South Eastern Nigeria | Agricultural workers | 0.3001 | Onuoha [20] |
| Britain | Male Adult | 0.2845 | Marras and Karwowsk [21] |
| Germany | Male Adult | 0.2834 | Marras and Karwowsk [21] |
| Russia | Male Adult | 0.2592 | Marras and Karwowsk [21] |