Fresh air respirators and/or active ventilation/toxic fume purging required for entry into such confined spaces. Very tragic result from chancing it.
Being a farm kid, I get what they were trying to do.
Dad once climbed into a similar pit, with 12 year old me as hole watch. He had a respirator, but not supplied air.
After I grew up and he started working in tow, we both realize how lucky we were.
And the correct Meters to Monitor All the different gasses and an O2 meter. And a Vent Fan/Hose to blow fresh air into the Confined Space. As well there should be a Safety Monitor and Rescue/Extraction crew and Equipment (Tripod Hoist and Emergency Medical grade Oxygen Tank and Mask.)
Oxygen is naturally present at a concentration of 21% in the air we breathe. The health effects described in this Fact Sheet may occur when breathing pure Oxygen or concentrations greater than 40%. * OSHA defines an Oxygen-deficient atmosphere as having less than 19.5% Oxygen by volume. * Always monitor Oxygen levels before entering any Confined Space.
AND THE PERSONALL ON SITE THAT KNOW HOW TO USE IT ALL !!!
Rescue and Ambulance crews no matter how fast may not arrive in time.
Face Mask Filters can filter certain odors and gases BUT if there is NO O2 in the air it won't matter shat filters you have.