Predictors of long working hour injuries occurring 9 or more hours into a shift. Multivariable logistic regression model* based on all reported injuries to MSHA Part 50 Program in U.S.: 1983–2015
| Adjusted OR (95% CI) | P-value | |
| Year of accident (1983–2015) | 1.02 (1.02 to 1.02) | <0.001 |
| Day of week of accident: sunday | 1.23 (1.17 to 1.28) | <0.001 |
| Less than 2 years of experience at current mine site | 1.13 (1.11 to 1.15) | <0.001 |
| Irregular shift start† | 2.85 (2.78 to 2.92) | <0.001 |
| Employed by a contractor (not operator) | 1.64 (1.59 to 1.69) | <0.001 |
| Canvass or class of commodity mined (based on industry code) | ||
| Anthracite and bituminous coal | Ref | |
| Metal | 1.52 (1.48 to 1.56) | <0.001 |
| Non-metal | 1.22 (1.17 to 1.26) | <0.001 |
| Sand and gravel | 1.71 (1.66 to 1.77) | <0.001 |
| Stone | 1.56 (1.52 to 1.59) | <0.001 |
| Mechanism or activity at time of accident | ||
| Ambient temperature heat related: atmosphere or environment | 1.96 (1.66 to 2.30) | <0.001 |
| Fall from: headframe, derrick, tower, ladder, machine, vehicle, equip, piled material, scaffolds, walkways and platforms. | 1.25 (1.21 to 1.30) | <0.001 |
| Flash burns (welding) | 2.08 (1.85 to 2.33) | <0.001 |
| Caught in/between/under running meshing objects, struck by flying objects and struck against moving objects while the employee conducting maintenance or repairs | 1.24 (1.13 to 1.35) | <0.001 |
| Mine fire | 1.74 (1.09 to 2.77) | 0.021 |
| Injury occurred offsite‡ | 1.32 (1.12 to 1.54) | <0.001 |
| Employee was not working at their regular job at time of injury§ | 0.89 (0.85 to 0.94) | <0.001 |
| Mine size category (average number of employees in year of accident) | ||
| Less than 20 | 1.52 (1.48 to 1.57) | <0.001 |
| 20–49 | 1.33 (1.30 to 1.37) | <0.001 |
| 50–99 | 1.17 (1.14 to 1.21) | <0.001 |
| 100–199 | 0.99 (0.96 to 1.02) | 0.625 |
| 200 or more | Ref |
*All the variables in the table represent the variables included in the final multivariable model. Sex and age were insignificant in the final multivariable model and were excluded.
†Based on MSHA data, most shifts start in specific windows of time in the morning, afternoon and evening shifts (92.2%). We accounted for irregular start times for each shift including shifts beginning between 00:31–05:29, 08:31–13:29 and 16:31–21:29, allowing for workers to arrive 30 min early or late for shifts in the morning (06:00–08:00), afternoon shifts (14:00–16:00) and night (22:00–00:00).
‡These include injuries to employees off of the mine property.
§These are workers whose regular job title was different from the job title they were working at the time of injury.
MSHA, Mine Safety and Health Administration.