The building in which I spend at least half of my waking
hours was built in 1850. Normally, I’m the only occupant in the office unit.
(There is residential unit with a mirror image floor plan on the other side of
the building.) After 40 years of familiarity with the structure, I
instinctively take into account its peculiarities. I know that the treads on
the stairs to the basement are narrow, and place my feet accordingly; I know
just how low the joists are in the basement and duck the appropriate amount
without looking. I know that the hinged trap door to the attic is absurdly
heavy and needs to be secured firmly in the open position before risking
letting go of it. I know which steam radiators to turn on and which to leave
off in order to balance the heat in the winter.
None of these will trouble
visitors, of course, but there is one peculiarity about which I always warn
them: the head room on the stairway to the second floor. The stairs themselves
are conventional, but the point at which they pass under the second floor is
not as high as on modern buildings, presenting a possible head-knocker. Going
up seems not to be a problem for anyone, but coming down can be a painful
surprise to people of my height or taller. A little more than half the time I
can descend the stairs with head held high and get away with it, but, if there
is any extra bounce to my step, thwack! It didn’t take too many repeats of
being brought to my knees before cocking my head to left or right on the
stairwell became completely unconscious; this buys just enough distance to keep
me headache free.
Stairs are dangerous enough as it is, especially when
descending. The second most common cause of accidental death, exceeded only by
car accidents, is falling down stairs. The most stairs I ever tackled at one go
were the 897 steps (with 50 landings) in the Washington Monument .
I descended, not ascended. One no longer is allowed to do either. While
security is cited as a reason, safety probably is a consideration too. Imagine
the poor paramedics having to stretcher an injured visitor stranded half-way up
the stairway.
Insurance actuaries have calculated the risks with their
usual precision. You will miss a step once every 2,222 times you use stairs.
This can result in anything from that jarring but harmless thud we’ve all
experienced to a full tumble. You will suffer pain once every 63,000 uses, modest
injury once every 734,000 uses, and hospitalization once every 3,516,667 uses.
This sounds like a pretty small hazard until one considers how many stairs we
encounter just on an average day. For some reason, the highest risk is on
stairways with four or fewer steps. Overconfidence perhaps. Some people are
especially inept at navigating stairs. It is not clear why, but 40% of injuries
on stairs are suffered by people who were injured on stairs before. Fit people
are actually more at risk than unhealthy people, probably (once again) through
overconfidence. Stairways steeper than 45 degrees or shallower than 27 degrees
give the most trouble. US building codes for new construction require risers of
no more than 7 inches (17.78cm) or less than 4, and treads (goings) of no less
than 11 inches (27.94cm) – which is a maximum of about 32 degrees.
Stairs are such an obvious solution to accessing a different
elevation comfortably that they appeared independently everywhere ancient
peoples ever built on multiple levels. The oldest surviving example, thanks to
the durability of stone, is 9000 years old at Jericho . The oldest wooden staircase still in
existence, improbably enough, is in a Bronze Age salt mine in Hallstatt, Austria . It is
safe to say stairs aren’t going away anytime soon. But, while navigating them,
remember to look up as well as down at one’s feet. Why? This blog was prompted
because I was distracted while reading a letter as I descended my office stairs
yesterday, and, for the first time in many years, neglected to cock my head.
Stairs uncovered at Jericho