AERMOD View: Choosing Pollutants

AERMOD is widely used for analyzing ambient air pollutant concentrations and is applied to buoyant and neutrally-buoyant releases. In AERMOD View, the Pollutant Type list is accessible through the Control Pathway's Pollutant / Averaging options. Many pollutant types serve as labels with no chemical transformations; however, certain pollutant names or combinations influence how AERMOD computes outputs. The following pollutants have special meaning in model runs:

• SO2 - Triggers a 4-hour half-life decay when the Urban dispersion coefficient is used; computes the distribution of daily maximum 1-hour concentrations in accordance with the National Ambient Air Quality Standards (NAAQS) when the 1-hour period is the only short-term averaging period
• NO2 - Required to use special options for simulating the conversion of NO to NO2, including ARM2, OLM, PVMRM, GRSM, and TTRM/TTRM2; computes distribution of daily maximum 1-hour concentrations in accordance with the National Ambient Air Quality Standards (NAAQS) when the 1-hour period is the only short-term averaging period
• PM-2.5 NAAQS (i.e., PM-2.5, PM2.5, PM25 or PM-25) - Restricts averaging periods to 24-hour and annual averages; limits meteorological data to complete years; the MAXDCONT option for analyzing contributions to NAAQS violations will only work across multiple years if meteorology is provided as a single multi-year set of files (i.e., no use of MULTYEAR option)
• PM-10 NAAQS (Pre 97) - For generating the high-sixth-high in five years

If the pollutant name is not listed, the OTHER selection can be used to define the pollutant name up to eight characters in length.

AERMOD's code can automatically apply optional deposition parameters for specific names assigned through the OTHER option. For Gas Deposition, the following IDs access diffusivity, cuticular resistance, and Henry's Law constants:

• HG0 (Elemental Mercury)
• HGII (Divalent Mercury)
• TCDD (Dioxin)
• BAP (Polycyclic Aromatic Hydrocarbons)
• SO2
• NO2

For Method 2 particle deposition, fine mass fraction and mean particle diameter values are automatically associated with these IDs:

• POC (Polycyclic Aromatic Hydrocarbons)
• AS (Arsenic)
• CD (Cadmium)
• PB (Lead)
• HG (Mercury