# Question about PM25 sensitivity to its precursor in CMAQ5.2 DDM
**URL:** https://forum.cmascenter.org/t/question-about-pm25-sensitivity-to-its-precursor-in-cmaq5-2-ddm/3834
**Category:** CMAQ-DDM-3D
**Tags:** cmaq
**Created:** [January 9, 2023, 2:38pm UTC](https://forum.cmascenter.org/t/question-about-pm25-sensitivity-to-its-precursor-in-cmaq5-2-ddm/3834 "2023-01-09T14:38:49Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Polaris](https://forum.cmascenter.org/u/Polaris)
#### Post date: [January 9, 2023, 2:38pm UTC](https://forum.cmascenter.org/t/question-about-pm25-sensitivity-to-its-precursor-in-cmaq5-2-ddm/3834/1 "2023-01-09T14:38:49Z")
Hello,
I am still a beginner in using CMAQ-DDM-3D and I have run successfully. But i meet some trouble now.
I want to obtain the sensitivity of PM25 to its precursors, so I need to know the sensitivity of each component of PM25 to the precursors, such as the sensitivity of SO2 and NOx can be set as follows(sensinput.dat file). But how do I set up my sensinput when I want to know the sensitivity of PM25 to primary PM25? Primary PM25 should contain primary sulfate, primary nitrate, primary ammonium, OC, EC and others.
```auto
ENX
EMIS
EGU, IND
SPECIES
NO, NO2
ES2
EMIS
EGU, IND
SPECIES
SO2
```
In addition, I would like to ask the SPECIES in the sensinput should be an emission species or a CMAQ model species.
The above are the problems I have encountered , I will appreciate your help.
---
### Author:  [@bandaoshutiao](https://forum.cmascenter.org/u/bandaoshutiao)
#### Post date: [January 9, 2023, 2:41pm UTC](https://forum.cmascenter.org/t/question-about-pm25-sensitivity-to-its-precursor-in-cmaq5-2-ddm/3834/2 "2023-01-09T14:41:40Z")
π π π π π π π π π π π π π π π π π π
---
### Author:  [@sergey](https://forum.cmascenter.org/u/sergey)
#### Post date: [January 9, 2023, 3:13pm UTC](https://forum.cmascenter.org/t/question-about-pm25-sensitivity-to-its-precursor-in-cmaq5-2-ddm/3834/3 "2023-01-09T15:13:16Z")
DDM-3D always calculates the sensitivity OF all species. To see them, you need to make sure you set the CMAQ script to write the species you want in the following variable:
setenv AVG\_CONC\_SPCS βO3 NO CO NO2 ASO4I ASO4J NH3β
This setting is shared for normal CMAQ output and DDM-3D output. You can also just get all of the species like this:
setenv AVG\_CONC\_SPCS βALLβ
The sensinput.dat file you display in your question defines of the sensitivity is TO.
So, to recap - sensitivity OF all species is always calculated TO the parameters you define.
Sergey
---
### Author:  [@sergey](https://forum.cmascenter.org/u/sergey)
#### Post date: [January 9, 2023, 3:14pm UTC](https://forum.cmascenter.org/t/question-about-pm25-sensitivity-to-its-precursor-in-cmaq5-2-ddm/3834/4 "2023-01-09T15:14:16Z")
For your second question, you do want to use CMAQ model species, such as ASO4J, ASO4I, etc.
Sergey