Horrible chemically burned bacon smell in nose after water reservoir runs dey

[wanery]

I have experienced the same thing, but I would describe the oder as a strong noxious chemical smell. 
My humidifier reservoir had run dry previously with no ill affects.  However, about a month ago I woke up practically gagging !  I recieved the AS10 used from my sister.  She said she'd never had that problem. 
After mulling it over, it came to me that the auto-humidity control was not in use before, but was turned on recently.  When the reservoir drys out, the machine may well be turning on the heater in an attempt to bring up the humidity. As there's no water, it simply heats the plastic resevoir causing off-gassing.  It has happened 2 more times with similar results, before I finally figured out the proper lever to fill. 
Unfortunately, during my last visit to my Pulmo, she was concerned about a rapid decline in my resting O2 sat. (I'd just had a SMW test three mnths. prior).  She scheduled me for a PF & SMW tests.  The only noxious stuff I've been exposed to is whatever that ResMed was blowing.

Really like to know what it is !  Does anyone know what type of plastic the reservoir is made from ?

Thanks,
Chris

PS: This is a great board.  Marvelous resource  brrn lurking on and off for s year or more.

[PaulaO2]

For me, if the humidifier runs dry, I wake up smelling something like ammonia. Then I sneeze all day. I always fill the tub as full as it can get every night.

I do not use distilled water, I use tap. I live in rural area with a spring.

[ahuman]

I wonder why there's not an automatic shutoff of the heating element when it runs dry.

The design for this seems improved in the Air11 as only the metal in the reservoir is directly heated. In the Air10 it looks like metal and some sort of plastic layer are heated?

[Sleeprider]

The Airsense and Aircurve 10 water chamber has been re-designed to have a round heating plate. The metal plate used to be under the entire reservoir, now it is much more confined to the actual heating are of the device humidifier. The new humidifier chamber is imaged below: