Expert-level air quality engineering covering pollutant sources, atmospheric dispersion, air quality standards, emission controls, and air quality modeling.
Criteria pollutants: CO, NOx, SOx, PM2.5, PM10, ozone, lead under NAAQS. HAPs: hazardous air pollutants, 187 listed under Clean Air Act. GHGs: CO2, CH4, N2O, HFCs regulated under climate policy. NAAQS: national ambient air quality standards, primary and secondary standards. AQI: air quality index 0-500, communicates health risk to public.
Point sources: stacks, vents, identifiable single emission points. Area sources: fugitive emissions, agricultural, small sources aggregated. Mobile sources: vehicles, aircraft, trains, significant urban contribution. Emission factors: AP-42 database provides emission factors by source category. Continuous monitoring: CEMS measure emissions in real time for major sources.
Gaussian plume: C = Q over 2 pi sigma_y sigma_z u times exponential terms. Stability classes: Pasquill-Gifford A through F, neutral D most common. Mixing height: limits vertical dispersion, varies diurnally. AERMOD: EPA preferred model for near-field dispersion from industrial sources. CALPUFF: Lagrangian puff model for long range and complex terrain.
Electrostatic precipitator: charge and collect particles, over 99% efficiency. Fabric filter: baghouse, PM control, efficiency depends on fabric and cleaning. Wet scrubber: spray liquid absorbs gas pollutants and large particles. SCR: selective catalytic reduction, NOx control using ammonia over catalyst. Thermal oxidizer: combust VOCs and HAPs at high temperature.
| Pitfall | Fix |
|---|---|
| Default met data instead of site-specific | Use on-site or nearest representative met station |
| Ignoring building downwash | Include building downwash for stacks near tall structures |
| Wrong emission factor for source type | Match AP-42 table to actual process conditions |
| Missing fugitive emissions | Fugitive sources often exceed stack emissions |