I was using "conflagration" to refer to some sort of out of control fire in which a structure within the rock shelter burned down and scorched the rock. Usually normal cooking or heating fires are built within structures in the shelter or else at a suitable distance from the shelter wall so that what you see as evidence of fire is smoke blackening, rather than reddening by direct fire. Later users sometimes build closer to the shelter wall, but that is usually obvious on inspection.<br><br>Where in Mexico were you caving? I have caved in Oaxaca, fortunately without the problems you describe. I think something a bit more protective than a bandana would be a little more suitable against airborne pathogens.