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Relationships of EF and enrichment degree of the chemical elements in dust.
| EF Values | EF ≤ 1 | 1 < EF ≤ 10 | 10 < EF ≤ 100 | 100 < EF ≤ 1000 | EF > 1000 |
|---|---|---|---|---|---|
| Level | Rarely enriched | Mildly enriched | Moderately enriched | Highly enriched | Extremely enriched |
| Rank | 1 | 2 | 3 | 4 | 5 |
| Source | Soil and crust source | Natural and artificial sources | artificial source | artificial source | artificial source |
EF: Enrichment factor.
