Table 3.
“On Fireline” one-minute mean CO exposures (ppm) of sampled WFFs, overall and by year (N=246)
| All years | 2015 | 2016 | 2017 | |
|---|---|---|---|---|
| Number of WFFs | 246 | 35 | 120 | 91 |
| Fireline duration (hrs), mean (sd) | 9.6 (2.7) | 10.6 (2.0) | 9.6 (2.6) | 9.3 (2.9) |
| Fireline CO exposure | ||||
| Mean (sd) | 4.6 (6.4) | 4.1 (3.9) | 4.7 (7.3) | 4.8 (6.1) |
| Mean (sd) adjusted to 8-hr shift | 5.6 (7.9) | 5.6 (5.4) | 5.4 (8.6) | 5.8 (7.8) |
| Geometric mean | 2.5 | 2.7 | 2.5 | 2.4 |
| Median | 2.3 | 2 | 2.2 | 2.3 |
| IQR (Q1, Q3) | 4.8 (0.9, 5.7) | 5.5 (1.2, 6.7) | 4.3 (1.0, 5.3) | 5.2 (0.7, 5.9) |
| 95th percentile | 15.6 | 12.6 | 14 | 16.7 |
| Maximum | 52.9 | 13.8 | 52.9 | 34.5 |
| Maximum one-minute mean within “on fireline” period | 600 | 597 | 600 | 566 |
| Mean (sd) number of 1-minute averages per WFF above CO OELs | ||||
| 16 ppm (NWCG) | 41.1 (64.0) | 42.3 (54.6) | 36.2 (61.1) | 47.1 (70.8) |
| 25 ppm (ACGIH) | 26.6 (47.5) | 26.3 (32.8) | 25.1 (51.3) | 28.7 (47.6) |
| 35 ppm (NIOSH) | 16.4 (35.5) | 15.6 (20.5) | 16.2 (41.6) | 17.0 (31.5) |
| 50 ppm (OSHA) | 9.6 (25.9) | 8.3 (12.0) | 10.0 (32.1) | 9.5 (20.5) |
| 200 ppm (NIOSH ceiling) | 0.4 (2.0) | 0.2 (0.7) | 0.4 (1.7) | 0.4 (2.5) |
Abbreviations: CO, carbon monoxide; ppm, parts per million; sd, standard deviation; IQR, interquartile range; Q1, 25th percentile; Q3, 75th percentile; OEL, occupational exposure limit; NWCG, National Wildfire Coordinating Group; ACGIH, American Conference of Governmental Industrial Hygienists; NIOSH, National Institute for Occupational Safety and Health; OSHA, Occupational Safety and Health Administration