First of all, thanks for good info on the contact cement(s). I would like to caution folks that down play the hazards of these chemicals. While I am by no means an expert on leather work, I am an expert in firefighting with 31 years. I responded to a fire in a shoe and boot repair shop where a man was using contact cement on a cold day. A space heater, in combination with the fumes, caused a flash fire that burned him and subsequently destroyed his shop. He survived however, with minor (1-2) flash burns. Could have been worse.
I don't mean to be an alarmist or discredit any post here; however, chemicals in these products are highly flammable and are damaging to lungs. Best practice is a well ventilated area. Positive pressure ventilation (e.g., a fan blowing into the space) with a exhaust exit is best. This method prevents a fan motor from being the ignition source. Air flow lowers the amount of vapor to air ratio, therefore it cannot have ignition. Masks are usually recommended by OSHA in situations like body shop paint booths where the painter is in close proximity the fumes and particles. Down draft ventilation is mostly used there. Vapor masks are expensive, cumbersome, and impractical in a leather shop setting.
Its important to note that there must be the right combination of vapor and air, along with an ignition source to produce a fire or explosion. If you ever want to know about any product Google the MSDS (Material Safety Data Sheet).
MHO