Se?or GORDON THREE,
Seeing how this thread FOCUSES on lead acid battery ventilation, trivializing the danger of lead poisoning is not a very wise choice of positions to take.
LEAD POISONING isn't like cyanide where you end up in a coffin with blue lips smelling like a box of almonds. Lead poisoning is subtle, and can lead to problems that defy rational analysis - like exacerbating heart rhythm problems, causing kidney and liver damage, ruining the level of immune system protection and too many other things to count.
This thread is not about how to prepare meringue for a pie, or how to shop for a tie, it is about handling lead acid batteries. So pardon me if I remark your trivialization borders on the incredible.