Estimated annual deposition rates of microfibers and plastic particles to national parks and wilderness areas of the United States. Data are based on observed deposition rates to each site from late 2017 to early 2019.
| National park or wilderness | State | Size (km2) | Mean plastic deposition rate (plastics m−2 day−1) | Metric tons of plastic per year (visual counts) | Metric tons of plastic per year (FTIR proportions) |
| Grand Canyon | AZ | 4926 | 112 ± 6 | 10.7–11.9 | 11.0–21.3 |
| Wind River Range | WY | 7252 | 68 ± 6 | 9.3–11.1 | 10.9–22.3 |
| Craters of the Moon | ID | 2893 | 139 ± 10 | 7.7–8.8 | 11.5–19.3 |
| Rocky Mountain | CO | 1047 | 435 ± 8 | 9.4–9.8 | 4.2–9.0 |
| Joshua Tree | CA | 3200 | 54 ± 2 | 3.4–3.7 | 3.7–9.8 |
| Uinta High Wilderness | UT | 1849 | 120 ± 6 | 4.3–4.8 | 1.6–2.8 |
| Canyonlands | UT | 1366 | 48 ± 7 | 1.2–1.5 | 3.0–6.1 |
| Indian Peaks | CO | 311 | 148 ± 5 | 0.9–1.0 | 0.4–1.3 |
| East River | CO | 300 | 140 ± 9 | 0.8–0.9 | 0.4–0.9 |
| Great Basin | NV | 312 | 107 ± 5 | 0.65–0.72 | 0.4–1.3 |
| Bryce Canyon | UT | 145 | 80 ± 6 | 0.22–0.26 | 0.4–0.8 |
| All western protected areas | USA | 496,350 | 132 ± 6 | 1012–2419 | 1185–3773 |