Each year there are numerous severe burns obtained by people using these grills. Dissimilar from most screw connections, propane tanks contain a reverse thread. After the grill is lit the operator may hear a hiss or smell leaking gas from the tank. Without turning the grill off, they attempt to tighten the connection but forget about the reverse thread. The operator mistakenly loosens the connection even more, then when the gas rises to the level of the hot coals, the operator becomes engulfed in flames.
Propane creates enormous heat so the burns can be very deep or even lethal.
The reason that the propane tanks have the reverse thread is to prevent them from being connected to oxygen tanks, which creates a highly explosive cocktail. So, always remember to turn propane connectors counter-clockwise and always turn off the grill before adjusting the connector. Correspondingly, these same women are also inclined to suffer from shortness of breath and wheezing. They are also slightly more likely to suffer from allergies and hay fever. Natural gas contains nitrogen dioxide, a substance known to be a lung irritant, and is probably the culprit.