Devices to measure carbon monoxide, aerosols, sulfur dioxide, and
hydrocarbons could all be bought o;
the shelf. He loaded the equipment
into some university trucks and set
out for the school’s weather observatory at Cheeka Peak. The little
mountain was an arduous ;ve-hour
drive northwest of Seattle, but it was
also known for the cleanest air in
the Northern Hemisphere. He reckoned that if he tested this reputedly
pristine air when a westerly wind
was blowing in from the Paci;c, the
Asian pollutants might show up.
Jaffe’s monitors quickly captured
evidence of carbon monoxide, nitro-
gen oxides, ozone, hydrocarbons,
radon, and particulates. Since air
from North America could not have
contaminated Cheeka Peak with
winds blowing from the west, the
next step was identifying the true
source of the pollutants. Ja;e found
his answer in atmospheric circula-
tion models, created with the help of
data from Earth-imaging satellites,
that allowed him to trace the pollut-
ants’ path backward in time. A paper
he published two years later sum-
marized his conclusions succinctly.
;e pollutants “were all statistically
elevated . . . when the trajectory origi-
nated over Asia.”
O;cials at the U.S. Environmen-
tal Protection Agency took note, and
by ;;;; they were calling Ja;e to talk.
;ey were not calling about aerosols
or hydrocarbons, however, as con-
cerning as those pollutants might
be. Instead, they were interested in
a pollutant that Ja;e had not looked
for in his air samples: mercury.
A factory worker
covered with
coal dust in Inner
Mongolia.
Previous pages:
Tianjin Steel
Plant, in China’s
Hebei Province.
