> In at least one case cited in the investigation, baking powder was mixed into food to make tourists physically unwell.
A small amount won't make a different, it'll just stimulate a bit more H+ production from your stomach's proton pumps.
Edit: The article I read claims the scam involved baking powder, which makes even less sense given that it's even more noticeable, bitter and metallic.
In aviation rules you can have passengers at 12k ft without oxygen for an unlimited amount of time. The crew needs to use oxygen if you're between 10k and 13k for more than 30 minutes. Above 13k both crew and passengers must use oxygen immediately (EASA rules, FAA is different).
So they seem to consider 12k to not be dangerous to passengers.
The highest peak in the contiguous United States is Mt. Whitney at ~14.5k feet
Many peaks in the western US are in that range. Lots more with several exceeding if you include Alaska in “the western US”.
Contiguous means the 48 connected (contiguous) states. It never includes Alaska.
And even though definitionally/officially continental could include it (it's in the same continent), in common use "continental US" is not meant to include Alaska either.
Other amusing things from that trip: we went up there the 3rd of July, and it snowed. We charged the car in Colorado Springs before we left, got up to the peak with 36% battery remaining. My wife worried we wouldn't be able to make it back. Got back to CS with ~70% battery left.
Even if you don't feel it, the altitude still makes a difference, though. I recall doing two-a-day hell weeks at Big Bear at the end of summer cross-country training in high school and there was a 5k up there at the end of that week. We all got worse times than typical at sea level, and somewhat amusingly, I recall a high school senior from Rim of the World High School (who lived up there) getting 2nd place overall the first year I ever competed in that race, beating way more seasoned competitors just because he was used to the altitude.
It works in reverse, too. There was an officer in my Armor Basic Officer Course from Colorado who gave himself rhabdo during the two-mile test the first week we in-processed, apparently because he was so used to altitude that he hadn't quite acclimated to Fort Knox atmosphere.
Not really. Altitude sickness seems quite random in who it effects worst. I trekked to the top of Mera Peak (~21,000 ft) many years ago. 3 of the fittest people in our party got altitude sickness and didn't make it to the peak.
It's "not that high", but people frequently do get AMS at those attitudes or even lower.
I'm not sure what point you're trying to make. People regularly experience AMS at the heights far below what OP mentioned, whether on the day they arrive or on days 2-4, and that's not even accounting for strenuous physical activity.