thanks for bumping this up. I will copy and paste a post of mine from another forum that is a graphic example of just how much CO is produced by a small 4 cycle gas engine.
"I went back to the big apartment job to write up the confined entry permit and give a hand with the pumps, about 2 years after we set the structures.
Things were going great and the atmosphere was testing good, until they started pressure washing the parking floor above.
As we all know, small engines have no emissions controls and put out more CO than a handful of clean running cars. Yeah Yeah, sure.
Today I got the demonstration.
This little Honda got that whole half a city block garage level above habitable levels, with huge fans exhausting the whole time.
We started the morning with ZERO CO on the meter, and suddenly it is over 25 and the alarm is squawking. I take a little walkabout and it is all bad, all over.
It is in the 25~35 PPM level, which is one hour max exposure. We get the crew above to cease with the pressure washing until we get done. In about 5 minutes the big garage fans clear it down below the alarm, and when I left it was back to zero again."
This is a certified Altair 4 gas meter that I get calibrated regularly. When I say huge exhaust fans, I mean the 6' diameter fans built into the structure for this purpose. Shortly after my alarm went off the entire building fire alarm started going off based on the CO detectors in the basement.
Set all the politics aside and look at the science. That little Honda defeated a parking garage's ability to cope, a place where a handful of cars could be running and moving. They really do put out the CO!
All it takes is a window open on the far side of a home and a bad door seal at an outside door to draw in enough CO from a generator to ruin your day. It does not have to be in the garage or the home to do it.