I use the mq135 sensor conected to arduino uno board. It can work along with to leds that arduino lights when air is corrupted or arduino also can be connected to pc or tablet to show the value of air quality. It detect CO2, CO, NH3...and sometimes its "strangely" up detecting bad air. I buyd the sensor mounted on a board so its very easy to conect.
Jan 14, 2019
Here is a link to a circuit that works fine detecting ectromagnetics waves power. http://reparandocosasdelhogar.blogspot.com/2013/06/construya-su-medidor-de-campo-de-rf.html#.XDy3U9J6RId I probed and it detect my rooter 2,4 GHZ very well, my telephone mobile when I call, a FM transmitter I built for testing it (I will frequency to see if the i can probe V2Skull ) and with my microwave. I made the circuit in a protoborad so I didn't need to soldier cables, and added a last stage of amplification, because he only uses 2 of the 4 ports from LM384 amplifier. Use 4,7 K from third amplifier to GND , and 20k + 50 K variable resistor from third output to third negative ampli. The positive thirdìnput takes from the output of that circuit I probed with 9V battery (and with 5V Arduino microcontroller) with third output connected to multimeter and to Arduino Analog Input Pin. The idea is try to detect if My body is emmiting signals, and also see if it detects microwave when I am burned (or to see if the whistle in my ears come from ultrasound or microwaves). I will post as soon I have the conclusions. Ah, add a 50 ohms resistor bettwen anntena (a simple cable for protoboard) and GND.