I have an emission rate data of PCDD/F, however it is very low (ex: 2,13E-10 g/s). If I put this value then AERMOD couldn't create a plot saying that the value is 0. What can I do?
If your pollutant does not chemically react with the atmosphere, you could enter the emission in ug/s and get a concentration in ug/m3 (or whatever unit you fancy). You could even set the emission to 1 and scale the results accordingly.