IAQ how to

First let me apologize for asking so many questions that may seem stupid or easy, to some of the more seasoned inspectors on the forums. Your feed back is valuable and a great resource to new inspectors like myself.

I just got a EXTECH EZ40 gas detection meter and was playing around with it last night. I followed the instructions to the letter for set up and calibration. When I was walking around the house (a typical split level) I got little of no “noise” when I was downstairs by the furnace and hot water heater, which is good, right? When I came up the stairs I started to get some “noise”, in the kitchen area, as I raised the meter closer to eye level it got even louder.
What dose this indicate? I do not have any gas appliances in my kitchen. Here is why this is so important for me to figure out. One for the obvious reason of knowing how to do my job, and two my wife suffers from severe headaches and fatigue. I am wondering if we have a “hidden” IAQ problem.

Can someone help e with what might be causing this?
Can some one tell me what I am doing right or wrong?
How to calibrate the meter correctly?

I welcome and appreciate any and ill informative feedback, and even a call

I looked it up, so it identifies all this stuff but it won’t tell you what? So what was in your kitchen? Naphtha? Alcohol? Steam? Smoke? Seems ta me this thing creates more heat than light, if you catch my drift.

“Quickly identifies and pinpoints gas leaks
High Sensitivity
One hand operation with thumb controlled sensitivity adjustment, to eliminate background gas levels
Visible and audible alarm at 10% (LEL) Lower Explosive Limit for methane
Locate the smallest leaks
Complete with 3 “C” batteries
Gas Detected:
Natural Gas
Carbon Monoxide (not to quantify)
Jet Fuel
Hydrogen Sulfide
Industrial Solvents
Lacquer Thinner