Greg Okin, a professor of geography at the University of California at Los Angeles, recalls being caught in a dust storm off Interstate 10 in the Coachella Valley some years ago. “You couldn’t see ahead of you, so you had to slo w do wn. But when you did, you started think- ing about what was behind you. What car was going to plow into you because it couldn’t see.” What Okin experienced was just one gust in a gathering storm. Blowing dust and brown- out conditions on January 19,
The problem has been building for a long time. Wars, oil and
gas exploration, agriculture,
cattle production, and general
development have broken up
soil surfaces around the world.
Drought, rising temperatures,
and a shift in some regions
from grasslands to shrublands
have accelerated the problem
in the past 10 to 15 years. In
the United States, the loss of
grasslands and other natural
shields that hold arid soils in
place is particularly pronounced
in New Mexico, Arizona, and
Nevada, where dust production has increased by orders of
magnitude over the past several
decades. And dust begets more
dust: It reduces the re;ectance
of the winter snowpack and
increases the absorption of
sunlight, causing snow to melt
sooner. Five times as much dust
now falls on the snowpack in
the Colorado Rockies as when
the area was ;rst heavily settled
in the mid-19th century.
Hence dust is both symptom
and cause of a grim type of
environmental decline: desertification, the degradation of
vital grasslands into barren and
unproductive desert. This process unfolded with horrifying
consequences in the 1930s,
when large portions of the Great
Plains states turned into the
Dust Bowl as a result of lack of
rain and poor farming practices.
Millions of acres of fertile topsoil blew east, toward and into
the Atlantic Ocean, devastating
American agriculture.
Deserti;cation is happening
today around the world, most
notably in northern China, home
to much of that nation’s 1. 2 bil-
lion citizens. “The world needs
more food, more land to grow
it, and more water to irrigate it,
yet we have the same amount
of land, less water, and higher
temperatures,” Okin says. “This
is a train wreck about to hap-
pen that will impact hundreds
of millions of people now and
perhaps billions in the future,
because that’s how many live
in dry lands worldwide.”
Last year was a record one
for dust production in the United
States, when sparse and badly
timed desert rains produced
the lowest vegetation cover
on record and 5 to 20 times
as much dust as usual from
the Colorado Plateau into the
mountains. The snowpack melt-
ed about 50 days early because
dust put massive stress on high
mountain vegetation and low-
land farms and ;elds. In south-
ern Colorado scientists reported
the most rapid snowmelt since
the mid-1980s, when records
were ;rst kept. “Increased run-
off caused by dust on snow-
pack acts as a major leak in the
reservoir system,” says Thomas
Painter, a professor of geogra-
phy at the University of Utah.
Dust is two-faced—a lesson
I am about to learn as my
plane descends to the desert
near Las Cruces, New Mexico,
where I am to meet Okin and
see his work. Dust can be ben-
e;cial to parts of the planet, as
when it travels from the Sahara
to the Amazon Basin, where
it deposits phosphorus that
helps keep the rain forest lush.
Similarly, dust from northern
China brings phosphorus and
other vital nutrients to the
Hawaiian Islands. Dust from
the many continents ferries
iron and phosphorus to the
ocean surface, promoting the
growth of phytoplankton and
other marine plants that feed
sea organisms and draw car-
bon dioxide out of the atmo-
sphere. Fine bits of degraded
rangeland in southern Africa,
THERE IS A REASON why the Hoover vacuum company has survived
more than 100 years—household dust is a universal nuisance. But
what exactly is lurking within that layer of dust on your dressing
table? Scientists are trying to find out, using house dust as a vehicle
for exploring what we are inhaling, what we are inadvertently ingesting, and what substances are potentially making us sick.
It turns out that a lot of dust is of our own making: tiny fibers from
our clothes, morsels from that crumbly coffee cake, and the estimated 7 million skin flakes a person sheds each minute. There are
also remnants of other living things, ranging from specks of plants to
living bacteria and fungi (such as Mycocladus corymbiferus, shown
magnified below) to decomposing insect carcasses and the fecal
droppings of microscopic mites.
Even after factoring in crumbs, shedding, and bugs, about 60
percent of house dust remains unaccounted for. That is where
open windows and the dirty soles of shoes come into play. This
year researchers from the U.S. Geological Survey published their
analysis of indoor dust, which uncovered numerous potentially
harmful outdoor chemicals, including polycyclic aromatic hydrocarbons used to coat parking lots and the pesticide DDT, despite
the fact that the Environmental Protection Agency banned it almost
40 years ago. Another study traced the migration of arsenic- and
lead-contaminated soil into the home. “We just don’t pay attention to
what’s under our feet,” says Barbara Mahler, an author of the USGS
study. “We track in a wide range of compounds.” ANDREW GRANT
THE SECRET LIFE OF DUST
