| • Pretreatment stage | |
| Sandblasting dust removal section | Metal dust (zinc/aluminum content 15–25%) and degreasing agent volatilization (trichloroethylene 50–120 mg/m³) mixed discharge |
| Automatic spraying section | High solid epoxy primer to produce paint fog (D50=15–30 μm, load 5–8 g/m³), VOCs initial concentration 2,000–4,000 mg/m³ |
| Drying and curing section | the exhaust gas temperature changes step by step (room temperature →140 ℃→60 ℃) |
| • Whole-container painting stage | |
| External spraying | the instantaneous peak of VOCs during the construction of polyurethane finish paint is 1,000–1,500 mg/m³ (lasting 15–25 min) |
| Internal touch-up | epoxy asphalt paint containing benzo[a]pyrene (2–8 μg/m³), paint fog particle size distribution of 0.5–5 μm |
| Repair process | local spot spraying causes pulse fluctuation of concentration (from 50 mg/m³ to 800 mg/m³ within 30 s) |
