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De Minimis Levels
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40 CFR 93 § 153 (PDF) (4 pp, 52KB) defines de minimis levels, that is, the minimum threshold for which a conformity determination must be performed, for various criteria pollutants in various areas. The information is summarized here:
| Pollutant | Area Type | Tons/Year |
|---|---|---|
| Ozone (VOC or NOx) | Serious nonattainment | 50 |
| Severe nonattainment | 25 |
|
| Extreme nonattainment | 10 |
|
| Other areas outside an ozone transport region | 100 |
|
| Ozone (NOx) | Marginal and moderate nonattainment inside an ozone transport region | 100 |
| Maintenance | 100 |
|
| Ozone (VOC) | Marginal and moderate nonattainment inside an ozone transport region | 50 |
| Maintenance within an ozone transport region | 50 |
|
| Maintenance outside an ozone transport region | 100 |
|
| Carbon monoxide, SO2 and NO2 | All nonattainment & maintenance | 100 |
| PM-10 | Serious nonattainment | 70 |
| Moderate nonattainment and maintenance | 100 |
|
| Lead (Pb) | All nonattainment & maintenance | 25 |