OUTDOOR SOUTHWEST - Desert Magazine of the Southwest

HOW WARM AIR LAYER TENDS TO TRAP SMOKE AND OTHER POLLUTANTS IN A DESERT VALLEY -
is sampling the air at Blythe, Indio and Palm Springs.
Tests for plant damaging materials have been made by
Los Angeles County in the Antelope Valley, while San
Bernardino County has measured the oxidant concentrations
in the Hesperia area.
WEATHER FACTORS CONDUCIVE TO DESERT AIR
POLLUTION ATTACKS HAVE BEEN STUDIED IN DETAIL.
While Southwest climate varies from that of a cool
high desert valley in Nevada to the warm valleys of the
Colorado Desert, certain conditions leading to potential
pollution are common to all. Basically, the weather
situation most likely to result in an air pollution attack
is the one that brings the nicest of weather. In this the
desert areas are similar to the coastal smog communities.
HOWEVER, WHILE LOS ANGELES HAS ITS SMOG
MAINLY DURING THE SUMMER AND EARLY FALL,
THE DESERT CONDITIONS OF WINTER BRING THE
GREATEST THREAT—THOSE QUIET SPELLS OF GENTLE
WINDS WHEN A STABLE AIR MASS SETTLES OVER
THE DESERT SOUTHWEST.
Under these conditions the air is most stable, so that
any pollutant added to the air tends to remain suspended.
When the build-up of these materials is great
enough, people take notice of the presence of air pollution.
During a period of air stagnation, cold air settles in
a valley. This air is overlain by warmer air above. Any
pollutant released near the valley floor will remaintrapped,
unable to rise because of the density difference
between the lower cold air and the overlying warm air.
As long as there is insufficient wind to move the polluted
air out, the pollution load will continue to increase.
A study made of the Antelope Valley by the Los
Angeles County Air Pollution Control District revealed
that this desert area's weather conditions are such that
potentially it could have about half the number of
smoggy days as does Los Angeles. Antelope Valley's bad
days would occur mainly in winter. The intense summer
heat of the desert effectively keeps the air stirred,
allowing any pollutant to disperse into the higher
atmosphere.
THE DESERT AREA WITH THE HIGHEST AIR POLLU-
TION POTENTIAL, BASED ON WEATHER FACTORS, IS
THE Low DESERT OF SOUTHEASTERN CALIFORNIA.
An expanding population and a valley configuration
conducive to eddying air currents, such as found in the
Coachella Valley, appear to make this region the one
with a pollution problem closest at hand. Evidence of
this may be seen in the generally low visibility observed
by the airport weather stations at Palm Springs and
Thermal. While the general desert visibility may be
40 miles or better, these stations will report a visibility
16 / Desert Magazine / October, 1961
WARM AIR
range of from 10 to 20 miles. And this is most often
haze (smog, if you will), not suspended dust from desert
dust storms.
HOW MUCH OF THIS POLLUTION LOAD HAS COME
FROM ACROSS THE MOUNTAINS FROM THE LOS
ANGELES BASIN IS NOT FULLY KNOWN.
However, there have been enough instances when the
air flow was such as to suggest that the haze of the
Coachella Valley is homemade.
One of the meteorological accomplices of the pollution
problem in Coachella is the reversing wind flow
that regularly occurs. A flow from the northwest is replaced
by one from the southeast.
THUS, AN INDIVIDUAL PARCEL OF POLLUTION MAY
BE CARRIED BACK AND FORTH ACROSS COACHELLA
VALLEY FOR SOME TIME BEFORE A FRESH WIND
CLEANS OUT THE VALLEY.
Can this process of progressive pollution of the desert
air be halted and reversed? While it has been stated
that the only positive control is to eliminate people, this
need not be the only solution. The people who choose
the desert in which to live, whether they made this
choice 50 years ago or just yesterday, deserve to breathe
the clean air they bought when they purchased their
piece of desert ground. Luckily, the desert is not a region
in the forefront of industrial and commercial
development.
BECAUSE OF THE DESERT AREA'S LEISURELY PACE
OF GROWTH THE DESERT DWELLER MAY SAFELY
AWAIT DEVELOPMENTS THAT ARE NOW A POSITIVE
NECESSITY TO RESIDENTS OF THE CROWDED COASTAL
BELT.
As air pollution control engineers succeed in muzzling
emissions with control devices, these devices can be
made mandatory on smog-making sources in the desert
communities. Present technology can provide controls
for almost all types of industrial sources, including
cement plants and milling and smelting operations.
When the automobile control is developed, as surely it
must, this can be added as a weapon against the fouling
of air.
THE GOAL OF CLEAN AIR FOR EVERYONE WILL BE
ACHIEVED ONLY THROUGH VIGILANCE.
New sources of power, new operations, all carry the
possibility of new pollution problems. But if controls
are applied as they are made available, the principle
of enough air for each man's vital functions, with no
one usurping the air of a community in which to dispose
of unwanted by-products of his activities, will be
attained in as complete a measure as is possible in the
imperfect social world. ///