At
indicate that if the general public were
during the day to 26 ug/ m? at night,
exposed to dust levels in excess of
Cape Kumukahi the nephelomcter measure-
1 mg/m°, the public healta problem from
ment was 9,2 ug/m>,
The
the dust alone might be enormous,
The greatest amount
of date is available for Mauna Loa Observa-~
reasonableness of the upper limit value
tory.
of 1 mg/m? is also demonstrated by data
3 ug/m?, and the nephelometer measure-
which indicate that nonurban ambient air
ments varied from 1.7 ug/ m? at night to
mass concentrations this high are usually.
6.5 ug/m? during the day,
associated with conditions described as
measurements made by the USAEC Health
dust storms !819.
and Safety Laboratory (HASL) were
Measurements of ambient air mass
Here, the NASN measurement was
3 ug/m?,
Additional
It is of interest in the present
loading can be used to further define a
context that Simpson?" made the following
reasonable estimate for predictive pur-
comment concerning the HASL measure-
poses,
ments:
The National Air Surveillance
"The HASL filter samples contain
Network (NASN) has reported suchresults
substantial dust (3-5 ug/ m° of air sampled)
for several years,
because of the fact that the filter was
Data”? for 1966 show
that there were 217 urban and 30 nonurban
located less than one meter above the
stations reporting,
ground surface near areas with substantial
The annual arithmetic
average for the urban stations ranged
personnel activity at the observatory site. "
from 33 (St, Petersburg, Florida) to
Thus, while this method of measurement
254 ug/m® (Steubenville, Ohio), with a
may not have coincided with Simpson's
mean arithmetic average for al} 217
interest, it does indicate that ambient
stations of 102 ug/m*.
air mass loadings may be very low on
For the nonurban
stations, the range was from 9 (White
such remote islands even when consider-
Pine County, Nevada) to 79 ug/m®* (Curry
able human activity is occurring nearby,
County, Oregon), with a mean arithmetic
On the basis of the above data, it
average for all 30 stations of 38 ug/m>,
would appear reasonable to use a value of
No data in this report are available for
100 ug/m® as an average ambient air
nonurban locations on small islands simi-
mass loading for predictive purposes,
lar to the Enewetak group; perhaps the
Indications are that this value should be
closest analog is the urban station at
quite conservative for the Enewetak
Honolulu,
Islands, and therefore allows room for
Hawali, which had an annual
arithmetic average of 35 ug/m>.
the uncertainty involved because the people
More pertinent, but limited, data have
themselves may generate a significant
fraction of the total aerosol.
Hawaii
the
1, 22 .
locations:
Data are
given for
three
Mauna Loa Observatory
located at a height of 3400 m, Cape
Kumukahi, and the city of Hilo.
NASN
bee
Ca
recently been published for the island of
Thercfore,
.
may be GNposed to higher particulate
eons
sar
a
to:
concentraiions than would be measured by
a stationary sampler,
Supporting evidence that 100 wim? is
data for Hilo (for an unspecified period)
a reasonable value to use for predictive
are given as 18 ug/ my and nephelometer
purposes is provided by the National
.
,
3
measurements varied from 18 upgim
Ambient vir Quality Standards” .
Here