Determine road-map for testing

[davclark]

Got this feedback from Ron Cohen:

In our experience step 1 is to show the low cost sensor you are proposing to use has an interpretable response to humidity and temperature variations that occur on the time scale of atmospheric humidity and temperature variations. You should do that in the lab in a chamber that has zero signal before anything more complicated. Most of the sensors for CO, O3, NO and NO2 on the market have temperature and water response functions that are so strong and complicated that is is difficult to extract a reliable outdoor measurement. We are working with some of the low cost sensors http://beacon.berkeley.edu/ and would be willing to help with calibration--delivering known quantitites of gases at varying T and RH, but only after you can show that whichever ones you are using are potentially interpretable.

After a lab cal, we can probably find a field site with data, but that is more difficult and involves more people.

I've asked if we could work with him on obtaining access to a reasonable lab environment.

[davclark]

More from Ron:

For Temperature testing and RH testing you don't need much of a lab. You can do T with a heat lamp on a large sealed baggie. For RH you do need to be able to mix wet and dry air. I can't offer access to my lab to students right now.

[davclark]

The temperature and humidity dependence of dust sensors isn't as troublesome as it is for other kinds of sensors. The main issue is moisture increasing the size of otherwise small particles. We could attempt to quantify as part of the project (especially if we can co-locate a sensor briefly with an EPA station).

Other kinds of sensors (measuring gases) are more difficult. We know that electrochemical sensors are much better than metal oxide sensors, but they still aren't foolproof. Ken McGary has already put a lot of work into characterizing some electrochemical sensors, so we could leave that out of the project and just focus on dust/particulates.

[petersand]

Do some research on sensor testing:

• what makes/models of sensor?
• PPD42
• PPD60
• ask Ken about others
• who do we talk to about co-locating with EPA/BAAQMD sensors? (talk to David Holstius)
• do we want air filters, etc.? (talk to David Holstius)

[petersand]

Additional sensors mentioned by Ken:

• Sharp GP2Y1010AU0F
• Sharp DN7C3CA006
• Alphasense OPC-N2