Carbon monixide mq7 data sample

Hello buddies!

I’m using the Carbon Monoxide Sensor - MQ-7. It is returning about 80 to 200 ppm, depending on the hour of the day.

I’ve been reading about values of CO that are acceptable and most of the information sources says that around 40ppm is acceptable.

My doubt is:
Is it correct that value i obtained?
do we created tolerance to CO? (I checked in [1] that there was no complaints of following exposure up to 115ppm for 8 hours daily)
ps: I followed that wiring [2]

[1] - http://gestis-en.itrust.de/nxt/gateway.dll/gestis_en/001110.xml?f=templates$fn=default.htm$3.0
[2]- AirQualityMQ135 \ Learning \ Wiring

The sensor does not directly read ppm, is sensitive to temperature and humidity, and has to warm up for 24 hours before you can expect stable readings. Read the sensor data sheet for details.