[af_vet_1981]

I worked for years at 14,000 ft and never got sick.

However most folks need to gradually work up to 14k; going up too fast tends to bring on altitude sickness which can be dangerous.

[mikey_hates_everything]

"most folks need to gradually work up to 14k"

When you travel to La Paz, Bolivia by plane, there's no gradual, you're at altitude walking out of the plane. The airport is at about 13,000', the city 12,000'. Takes about 4 hours for the beer buzz to wear off. I worked there in my late 40's, never needed the roving O₂ van. Don't know about now but I wouldn't want to deal with it.