Scuba Diving
www.seagrant.wisc.edu
Twenty-Five Years of Enhancing Diving Safety
Three decades ago, the popular Undersea
World of Jacques Cousteau made scuba
diving seem as natural as a walk in the
park. But for human beings, it’s an alien
world beneath the waves, and scientists
are still learning how the body and the
brain react to being there.
Sea Grant has been advancing this
knowledge for a quarter century. In the
early 1980s, UW Sea Grant-supported
researchers assessed the risks to fetuses
posed by pregnant women who dive and
helped design some of the first dive computers,
now widely used by divers to
monitor how long they can safely remain
at depth. Today, UW Sea Grant-supported
scientists are increasing our understanding
of the body’s susceptibility to
decompression illness and the brain’s
penchant to panic while diving.
The program began in the late 1970s,
when prominent diving scientist Edward
Lanphier moved to
afterward, Wisconsin Sea Grant helped
UW-Madison purchase a chamber that
achieves pressures equivalent to 1,000
feet underwater or 16,000 feet in the
atmosphere.
Lanphier first focused on finding an
animal model that closely reflected the
human response to pressurized environments,
determined in part by body weight
and rates of gas exchange in tissues. After
finding sheep suitable, Lanphier and
others conducted some of the first controlled,
experimental assessments of the
causes and effects of the bends and other
forms of decompression sickness.
The “bends” refers to tingling, numbness
or pain divers may feel if they dive
too deep, stay down too long or surface
too quickly. The sensations are mostly
caused by bubbles of nitrogen forming in
bone, muscle or other tissues. In the pressurized
underwater environment, more
nitrogen than usual is dissolved in these
tissues. When divers ascend too quickly,
pressure on their bodies decreases rapidly
and allows dissolved nitrogen to form
into bubbles.
Formal diving instruction teaches recreational
divers to minimize the risk of the
bends by adhering to prescribed dive
tables, which indicate how long a diver
can safely remain at depth. However,
commercial, military, scientific and some
recreational divers sometimes exceed
those recommendations, and the risks of
doing so have been poorly understood.
