Originally posted by muzzleflash
This is cool but you can call me spoiled, because I think these sensors would be mostly useless. The only one I can see being really helpful is the
natural gas sensor, although we can smell that normally with our noses. Of course I am talking about processed natural gas with odorant added to it,
in the case of a natural gas well leak you would not smell anything, but how often does that actually transpire?
If you really want a good system, you will need dozens of accurate sensors capable of identifying an entire plethora of contaminants, anywhere from
mercury to radioactive pollutants.
In all practical senses this is extremely expensive due to the tons of potential contaminants you may want to look out for.
I do however believe that everyone should be supplied this type of equipment and that humans should make it a normal procedure to scan their
environment and take whatever actions to deal with it. But that's a pie in the sky ain't it? 
Well in the case of survival, since we don't know what the apocalypse will entail, and since everything costs a fortune, you have to be
resourceful.
So in this example it tests for VOC's which are volatile organic compounds. Thats might be bio-weapons right there. Or gases from a chemical fire in
the air blows your way while the city burns.
What you want to do is have a detector as he says in the video there that can detect dangers other than just smoke like a smoke detector.
So the one link I posted checks for atmospheric quality and it costs 6 bucks. Well thats cheap because most systems to test if the air is breathable
are over 2 thousand dollars. You know something like
this explorer
So the idea is, is it safe to go outside? To let your kids go outside after some event? Do you just go out there like they used to in the old 50's
sci fi movies, send one guy out, he turns and says, "its ok, the atmosphere is just like earth!"
Reality is that if you go out there, you may collapse immediately and die.
So if you can make a detector system for 100 bucks, that will tell you when you must close the windows right now, that would be a good thing to have.
Now for me, its part of a larger project.
Here is another cool device.
Ultrasonic motion detector rangefinder good up to 18 meters. so 60 feet.
It will track anything moving, up to 60 feet away. Without a red beam like an infrared laser targeting device.
And how much is it? Long Range Ultrasonic sensor
2 for $3.90
So for me, I want to outfit a mobile safe room. And so motion sensors are a good idea to see who is outside the truck. They can track a moving subject
and record video.
The atmosphere sensor so that I know its safe to open the vents after or during a fire in the area.
CO2 sensor, so that I know the air is still safe to breathe inside the truck.
O2 sensor to see if I am creating too much Oxygen with my O2 electrolysis generator.
A Hydrogen sensor to see if my hydrogen venting system is leaking explosive gas into the truck.
etc. Simple and fun projects to do with the Arduino and cheap like borsch.
