REPORT FOR CONSULTATION ON THE
SAN FRANCISCO BAY AREA
AIR QUALITY CONTROL REGION
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
National Air Pollution Control Administration
-------
REPORT FOR CONSULTATION ON THE
SAN FRANCISCO BAY AREA
AIR QUALITY CONTROL REGION
U. S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
National Air Pollution Control Administration
December 1968
-------
TABLE OF CONTENTS
PREFACE 3
INTRODUCTION 4
PROPOSED REGION 10
EVALUATION OF URBAN FACTORS 15
EVALUATION OF ENGINEERING FACTORS 25
-------
PREFACE
The Secretary, Department of Health, Education, and Welfare, is
directed by the Air Quality Act of 1967 to designate ''air quality
control regions" to provide a basis for the establishment of air quality
standards and the implementation of air quality control programs. In
addition to listing the major factors to be considered in the development
of region boundaries, the Act stipulates that the designation of a region
shall be preceded by consultation with appropriate State and local
authorities.
The National Air Pollution Control Administration, DHEW, has
conducted a study of the San Francisco Bay Area, the results of which
are presented in this report. The Region* boundaries proposed in this
report reflect consideration of available and pertinent data; however,
the boundaries remain subject to revisions suggested during consultation
with State and local authorities. Formal designation of a Region will
follow the consultation meeting. This report is intended to serve as
background material for the consultation.
The Administration appreciates assistance received either directly
during the course of this study or indirectly during previous activities
in the San Francisco Bay A'rea from the California State Department of
Public Health, Bay Area Air Pollution Control District, Association of
Bay Area Governments and the San Francisco Bay Area Council.
*For the purposes of this report, the word region, when capitalized,
will refer to the San Francisco Bay Area Air Quality Control Region. When
not capitalized, unless otherwise noted, it will refer to air quality
control regions in general.
-------
INTRODUCTION
"For the purpose of establishing ambient air
quality standards pursuant to section 108, and for
administrative and other purposes, the Secretary,
after consultation with appropriate State and local
authorities shall, to the extent feasible, within
18 months after the date of enactment of the Air
Quality Act of 1967 designate air quality control
regions based on jurisdictional boundaries, urban-
industrial concentrations, and other factors
including atmospheric areas necessary to provide
adequate implementation of air quality standards.
The Secretary may from time to time thereafter, as
he determines necessary to protect the public health
and welfare and after consultation with appropriate
State and local authorities, revise the designation
of such regions and designate additional air quality
control regions. The Secretary shall immediately
notify the Governor or Governors of the affected
State or States of such designation."
Section 107(a)(2), Air Quality Act of 1967
THE AIR QUALITY ACT
Air pollution in most of the Nation's urban areas is a regional
problem. Consistent with the problem, the solution demands coordinated
regional planning and regional effort. Beginning with the Section quoted
above, in which the Secretary is required to designate air quality control
regions, the Air Quality Act presents an approach to air pollution control
involving closely coordinated efforts by Federal, State, and local
governments, as shown in Figure 1. After the Secretary has (1) designated
regions, (2) published air quality criteria, and (3) published corresponding
documents on control technology and associated costs, the Governor(s) of
the State(s) must file with the Secretary within 90 days a letter of intent,,
indicating that the State(s) will adopt within 180 days ambient air
quality standards for the pollutants covered by the published criteria
-------
HEW designates
air quality
control regions.
HEW develops and
publishes ajr
quality criteria
based on scientific
evidence of air
pollution effects.
HEW prepares
and publishes
information on
available control
techniques.
States hold
hearings and
set air quality
standards in the
air quality
control regions.
HEW
reviews
State
standards.
States establish plans for implementation,
considering factors such as:
• Existing pollutant levels in the region
• Number, location, and types of sources
• Meteorology
• Control technology
• Air pollution growth trends
Implementation plans would set forth
abatement procedures, outlining factors
such as:
• Emission standards for the categories of
sources in the region.
• How enforcement will be employed to
insure uniform and coordinated control
action involving State, local, and regional
authorities.
• Abatement schedules for the sources tc
insure that air quality standards will ne
achieved within a reasonable time.
HEW reviews
State implementation plans, j
i
States act to control air
pollution in accordance with
air quality standards and plans
for implementation.
Figure 1. Flow diagram for State action to control air pollution on a regional basis.
-------
and control technology documents and adopt within an additional 180 days
plans for the implementation, maintenance, and enforcement of those
standards in the designated air quality control regions.
The new Federal legislation provides for a regional attack on air
pollution and, at the same time, allows latitude in the form which regional
efforts may take. While the Secretary reserves approval authority, the
State(s) involved in a designated region assumes the responsibility for
developing standards and an implementation plan which includes admini-
strative procedures for abatement and control. Informal cooperative
arrangements with proper safeguards may be adequate in some regions,
whereas in others, more formal arrangements, such as interstate compacts,
may be selected. The objective in each instance will be to provide
effective mechanisms for control on a regional basis.
PROCEDURE FOR DESIGNATION OF REGIONS
Figure 2 illustrates the procedures used by the National Air
Pollution Control Administration for designating air quality control
regions.
A preliminary delineation of the region is developed by bringing
together two essentially separate studies - the "Evaluation of Urban
Factors," and the "Evaluation of Engineering Factors."
The study of "Urban Factors" encompasses all considerations of a
non-engineering nature. It reviews existing governmental jurisdictions,
current air pollution control programs, present concentrations of
population and industry, and expected patterns of growth. Other non-
engineering factors are discussed when they are relevant. As a whole,
-------
ENGINEERING EVALUATION
Input
• Emissions
• Meteorology
• Physical Dim.
Computer
Pollutant
Diffusion
Model
Output
Iso-lntensity
Graphs
Existing Air
Quality
Sampling
Data
URBAN FACTORS
• Jurisdictional Boundaries
• Urban-Industrial Concentrations
• Cooperative Regional Arrangements
• Pattern and Rate of Growth
• Existing State and Local Air
Pollution Control Legislation & Programs
ALTERNATE
ENGINEERING
EVALUATION
Existing Air
Quality
Sampling
Dsta
Input
• Emissions
• Meteorology
• Physical Dim.
Preliminary
Delineation
of
Regions
Consultation
with State
and Local
Officials
Formal
Designation
by
Secretary-HEW
Figure 2. Flow diagram for the designation of air quality control regions.
-------
8
the study of urban factors indicates how large an air quality control
region must be in order to encompass expected growth. It also considers
which group of governmental jurisdictions will most effectively administer
a strong regional air quality control program.
The study of "Engineering Factors" indicates the locations of
air pollution sources, estimates of their emissions, and the geographic
extent and behavior of air pollutant concentrations in the ambient air.
Pollution concentrations in the ambient air are presented from air
quality sampling data obtained from the local air pollution control
agencies. The behavior and transport of air pollution within the
proposed region are described in terms of meteorology characteristic to
the Bay Area. This alternate study of engineering factors is a substitute
for the diffusion model technique, a basic tool which projects theoretical
air quality levels from meteorological and air pollutant emissions data.
The diffusion model was not used because there is a wide geographic variation
in terrain in the San Francisco Bay Area which produces a variety of
meteorological conditions. Diverse meteorological situations obviate
using an average seasonal or annual meteorological condition for the whole
area for input to a general diffusion model. This alternative method of
describing the behavior of air pollutants in the area in lieu of the
diffusion model can also serve as a guide to the appropriate size of the
air quality control region. As a whole, the engineering study indicates
how large the air quality control region must be in order to encompass
most pollution sources and most people and property affected by those
sources.
-------
The conclusions of the engineering study are combined with the
results of the urban factors study to form the basis of an initial
proposal for an air quality control region. As shown in figure 2, the
proposal is then submitted for consultation with State and local officials.
After reviewing the consultation record, the Secretary formally
designates the region with a notice in the Federal Register and notifies
the governors of the States affected by the designation.
The body of this report contains the proposal for the boundaries
of the San Francisco Bay Area Air Quality Control Region and supporting
studies on engineering and urban factors. The report itself is intended
to serve as the background document for the formal consultation with
appropriate State and local authorities.
-------
10
THE PROPOSED REGION
Subject to the scheduled consultation, the Secretary, Department
of Health, Education, and Welfare, proposes to designate an air quality
control region for the San Francisco Bay Area consisting of the following
jurisdictions:
Alameda County
Contra Costa County
Marin County
Napa County
San Francisco County
San Mateo County
Santa Clara County
Solano County
Sonoma County
As so proposed, the San Francisco Bay Area Air Quality Control Region
would consist of the territorial area encompassed by the outermost boundaries
of the above counties. The proposed region is illustrated in Figure 3.
DISCUSSION OF PROPOSAL
To be successful, an air quality control region should meet three
basic conditions. First, its boundaries should encompass most pollution
sources as well as most people and property affected by those sources.
Second, the boundaries should encompass those locations where industrial
and residential development will create significant air pollution problems
in the near future. Third, the boundaries should be chosen in a way which
is compatible with and even fosters unified and cooperative governmental
-------
11
Wenaoc.no
. Proposed
Figure 3. ^/Quality
Bay
-------
12
administration of the air resource throughout the region.
The "Evaluation of Urban Factors" indicates that the present high
densities of population and industrial activity, and hence the trans-
portation arteries supporting them, are primarily centered in the southern
five counties of Contra Costa, San Francisco, San Mateo, Alameda and Santa
Clara. Substantial growth will continue in these counti.es , but highest
rates of growth are projected for the counties of Marin, Sonoma, Napa,
Solana, and Contra Costa.
The "Evaluation of Engineering Factors" indicates that at the present
time most air pollution sources affecting the air quality of the San
Francisco Bay Area are included within the boundaries of nine counties:
Sonoma, Napa, Solana, Marin, Contra Costa, San Francisco, Alameda, San
Mateo, and Santa Clara.
Engineering data show that air pollution is primarily emitted near
the shoreline of the Bays and transported to portions of the nine county
Bay area, primarily in the valleys of these counties which border on the
San Francisco, San Pablo and Suisun Bays, (Figure 4). The data also
indicates that under certain meteorological conditions some air pollution
does travel from the San Pablo Bay area into the Sacramento Valley via the
Carquinez Strait. Due to sufficient mixing and dilution of air pollutants
as they enter the fringes or buffer zone between the San Francisco Bay Area
and the Sacramento Valley, the air pollution impact on the latter does not
appear significant for considering the portions of these Sacramento Valley
counties for inclusion in the San Francisco Bay Area Air Quality Control
Region.
-------
13
nmt
nxaaf
Figure 4- Topography of the San Francisco Bay Area.
(Adapted from Patton^)
-------
14
As proposed, the Region boundaries are coterminous with the nine
counties of the following: (1) the proposed expanded Bay Area Air Pollution
Control District basin, (2) the Preliminary Regional Plan for the San
Francisco Bay Region by the Association of Bay Area Governments, and (3)
the Air Basin designated by the State of California Air Resources Board.
In view of these above observations, the San Francisco Bay Air
Quality Control Region, consisting of the nine counties proposed herein,
is considered to be the most cohesive and yet inclusive area within which
an effective regional effort can be mounted to prevent and control air
pollution in the urban area surrounding the San Francisco Bay. The
remaining two sections of this report describe the initial evaluation of
urban and engineering factors.
THE CONSULTATION
The purpose of the scheduled consultation with appropriate State
and local officials is to receive comments and suggestions regarding this
proposal. Comments of the appropriate State and local officials will be
pertinent to the final disposition* of the proposal.
*When air quality control region boundaries have been designated, a
situation may develop involving a source of pollution on one side of the
region boundary which affects in some real way air quality on the other
side of the boundary. If adjustment of the boundary is not a practical
way to alleviate the situation, relief should be found in the control
implementation plan which follows the designation. The plan should contain
provisions for the control of sources located close to but beyond the region
boundaries. The level of control for such sources should depend, in part,
upon the degree to which emissions from the source cause air quality levels
to exceed the standards chosen for applications within the region.
-------
15
EVALUATION OF URBAN FACTORS
INTRODUCTION
The evaluation of urban factors, (land use, population, transportation,
and existing governmental organizations), is influenced by the regions main
physical characteristics, the mountains surrounding the San Francisco Bay,*
the valleys that tie these mountains to the San Francisco Bay, and the San
Francisco Bay, the largest natural harbor in the world, covering 450 square
miles. The nine counties, (Figure 5), that are tied into this physical
relationship thus become economically and socially interrelated.
LAND USE
For necessary area-wide cooperation and coordination of policies, plans,
and services, the Association of Bay Area Governments was created in 1961
to solve problems, formulate and implement regional development policies for
those nine counties. Their work in regional planning reveals existing and
future air pollution source and receptor areas. Industrial point sources
are reflected in industrial zoning. Air pollution receptor areas are
related to residential zoning. Mobile source distributions become meaningful
from transportation planning. Industrial activity and projections of
industrial development, are shown in Fig. 5 which shows land use, 1965, and
permitted development for the San Francisco Bay Region. Most industrial
development will occur in a continuous band immediately surrounding the Bay.
Substantial increases in industrial permitted development are planned along
the shores of Contra Costa, Solano, and Alameda Counties, owing to excellent
water and land transportation.2 (The industrial zoning projected towards the
*The San Francisco Bay, San Pablo Bay, and Suisun Bay will be referred
to in general as the San Francisco Bay.
-------
16
Industrial,
I Industrial \ SA*i
Permitted Devel-
opment
Residential, 1965,
and Residential
Permitted
Development
Figure 5. Land use, 1965, and permitted development for land area
covered by the Preliminary Regional Plan for the San
Francisco Bay Region.(Adapted from The Association of
Bay Area Government's Preliminary Regional Plan )
-------
17
Bay from San Mateo and Alameda counties is not an indication of projected
heavy industrial development but rather a result of adjacent city zoning
laws which define city boundaries extending to the county lines in
waterfront areas.)
Contra Costa County is the site of heavy industrial activity within
the nine county area with present and future developments showing substantial
increases. Large oil refineries are located at Richmond, Oleum, Martinez,
and Avon, with future developments in Hercules and Pittsburgh. Large metal
and steel mills, chemical plants, wood product plants, transportation
oriented plants, powerplants, and asphalt plants exist in the county or
are scheduled for completion in the near future.
Solano County is primarily agricultural in nature. Two governmental
installations, Travis Air Force Base, and Mare Island Navy Yard in addition
to one of the best equipped industrial park developments, Benicia
Industrial Park, are located in the county. This industrial park is
California's largest port oriented industrial park, consisting of over
40 companies, and a large refinery.
Alameda County in 1965 ranked third among California counties in
the number of manufacturing plants The manufacturing is not considered
l
heavy industrial, with the food processing industry being the largest of
the counties manufacturing economy, with production of transportation
equipment, metal products and machinery following in that order. Extensive
harbors, airport facilities, and highways provide the necessary routes of
o
transportation to sustain this extensive manufacturing.-3
-------
18
The trend in manufacturing employment density by county^ is shown
in Fig. 6 indicating noticable increases in the northern counties of
Sonoma, Solano, and Marin.
POPULATION
Population projections show that by 1990 close to 7.2 million persons
will be living in the Bay Region. Fig. 7 shows the 1960 population and
projections for 1970 and 1990 by county. Substantial population increases
will occur from 1960 to 1970 in Sonoma, Marin, Contra Costa, and Santa
Clara counties with continued high population increases projected for
Sonoma, Napa, Marin, and Contra Costa counties. The permitted development
land use map, Fig. 5, shows the planned residential areas necessary to
accommodate these projected population increases.
In summary, most counties will continue to grow at their present
accelerated rates for the next 10 years. Starting in 1980 the bulk of
new growth will shift to the north Bay counties including Contra Costa
County.
TRANSPORTATION
The regional transportation plan, (Fig. 8), shows the major trans-
portation arteries—mainly major highways, rapid transit routes, and
shipping channels—interwoven in the nine county area. Dense highway, and
rapid transit systems are located adjacent to the Bay to accomodate the
concentrated industrial-commercial and shipping establishments. Standard
freeways and special expressways are distributed in the outlying areas to
accomodate residential developments. With the completion of the Bay Area
Rapid Transit District (BARTD) system in 1972, and conversion of some
-------
19
Meno'ocino
SAN FRANCISCO
BAY XREA
Figure 6. 1960 and 1990 manufacturing employment densities
by county, (workers per square mile), and percent
increase.
-------
20
Mcndocino
908
1,150 27%
1,505 31%
Alameda
10
miles
SAN FRANCISCO
BAY AREA
\ T
Figure 7. Population increases by county. (Values represent thousands
of people for 1960, 1970, and 1990, and percent increase for
intervals.)
-------
21
TRANSPORTATION PLAN
SUPERFREEWAYS •—
STANDARD FREEWAYS —~
SPECIAL EXPRESSWAYS
RAPID TRANSIT •»•
SHIPPING ROUTES
PORT AREAS t
Figure 8. Transportation Plan for the San Francisco Bay Area.
(Adapted from The Association of Bay Area Government's
Preliminary Regional Plan )
-------
22
existing railway systems to rapid transit in place of a comparable road
improvement program, "at peak demand hours, all available major highway
space will be fully used in the future."^ This is noteworthy since the
air pollution emissions estimated^ for the Bay area show 75% of the carbon
monoxide, 54% of the nitrogen oxides and 48% of the organic compounds,
(the last two being the key photochemical pollutants), are emitted from
motor vehicle exhaust.
EXISTING GOVERNMENTAL ORGANIZATIONS
Another important factor to consider for air quality control region
boundaries is existing agencies or governmental units to administer an
effective air quality control program. The Bay Area Air Pollution Control
District (BAAPCD) presently consists of six counties, Alameda, Contra
Costa, Marin, San Francisco, San Mateo, and Santa Clara. The law that
originally established the BAAPCD in 1955 included three additional
counties, Napa, Solano and Sonoma, which have not as yet become active
in the BAAPCD. The California State Air Resources Board is considering
their active membership in the BAAPCD.
The BAAPCD program has a present annual operating budget of $1,443,346
with $208,275 contributed by a Federal Air Pollution Control Program
maintenance grant.
The jurisdiction of the Bay Area Air Pollution Control District is
limited to stationary, rail, and sea transportation sources. Gasoline
and diesel powered motor vehicles are the responsibility of the State
of California Air Resources Board. Close cooperation exists between
these two governmental bodies on this important air pollution problem.
-------
23
This multicounty district is governed by a Board of Directors who
receive assistance from a 20 man Advisory Council appointed by the
Board, and operates on a performance standard basis rather than a
permit system.
The BAAPCD presently employs 84 people in technical, clerical,
and administrative positions. The enforcement Division consists of
inspection (30 inspectors), engineering (inventory and compliance),
source testing, statistical and agricultural sections The technical
division embraces a library, a comprehensive laboratory, and an air
analysis section consisting on six complete continuous air
monitoring stations and 34 partial stations.
In addition, the State of California Air Resources Board has
recently approved the nine-county San Francisco Bay Area Basin, (Fig. 9),
as one of eleven California Air Basins The basins were selected on the
basis of homogenous air pollution problems, topography, meteorology,
and population density, and were required by 1967 State Legislation in
order that State Air Quality Standards can be set.
-------
24
STATE OF CALIFORNIA
FIG. 9 DESIGNATED AIR BASINS
BASIN NO.
DESIGNATION
North Coast
S.F. Bay Area
North Central Coast
South Central Coast
South Coast
Northeast Plateau
Sacramento Valley
San Jnaauin Valley
Great Basin Valleys
Southeast Desert
San Diego
1
N
50
miles
-------
25
EVALUATION OF ENGINEERING FACTORS
Introduction
The standard procedure for defining air quality control regions
has been to apply a diffusion model . The model is used with appropriate
emission inventory and meteorological data to estimate air pollution
distribution patterns for various pollutants. The use of the model is
restricted to areas where the terrain is essentially level, and marked
land-sea contrasts do not exist, (reflecting homogenous meteorological
conditions). The model (without considerable refinement) could not be
applied to the San Francisco Bay area. An alternate procedure, relating
qualitatively emission source information, air quality data, and
meteorological descriptions, (air flow patterns, mixing depths, and
diffusion potential), was used for the purpose of determining a logical
air quality control region boundary.
Most of the discussion in this evaluation is concerned with the
nine counties, (Sonoma, Napa, Marin, Solano, Contra Costa, Alameda,
Santa Clara, San Mateo, and San Francisco). In those cases in which a
statement applies in general or to a substantial majority of the nine
counties references are made to the Bay Area.
Emissions Inventory
Table 1 shows the distribution by pollutant of the major air pollution
emissions, (compiled by the BAAPCD), in tons per day by county for the nine
county area. Table 2 breaks down these emissions into source categories
for the original six county Bay Area Air Pollution Control District.
1967 estimates indicate about 12,000 tons per day are emitted from the
nine county area with Santa Clara, Contra Costa and Alameda Counties
-------
TABLE 1. BAY AREA AIR POLLUTION EMISSIONS BY TYPE, AND BY COUNTY, 19675
San Mateo
Santa Clara
San Francisco
Alameda
Marin
Contra Costa
Napa
Solano
Sonoma
Area Total
Particulates
31
52
23
43
5
56
8
28
34
280
Pollutants in Tons/day
Organic s
257
612
267
549
84
390
65
179
177
2580
Nitrogen
Oxides
51
92
76
106
17
172
8
29
25
576
Sulfur
Oxides
4
8
16
12
2
387
2
45
2
478
Carbon
Monoxide
890
1869
923
1564
305
1352
191
523
544
8161
Total
1233
2633
1305
2274
413
2357
274
804
782
12075
-------
27
TABLE 2 - AIR POLLUTION EMISSIONS IN THE BAY AREA AIR POLLUTION
CONTROL DISTRICT - 19675
TONS PER DAY
Source Category
Petroleum
Chemical
Metallurgical &
Mineral
Organic Solvent Users
Combustion
Inc iner at i on
Agriculture
Ships & Railroads
Aircraft
Tractors & Const.
Equipment
Sub-Total —District
Jurisdiction
Highway Motor Vehicles
Particu-
lates
2.4
30
26
5.8
27
29
18
6.7
8.8
19
172
38
Organic
Compounds
187
28
2.5
327
55
301
186
6.1
8.3
31
1132
1027
Nitrogen
Oxides
9.4
0.7
7.6
0.1
186
1.0
0.1
7.7
6.9
16
235
279
Sulfur
Oxides
57
78
75
—
182
1.6
0.5
9.5
—
5.1
409
20
Carbon
Monoxide
443
8
0.6
—
0.8
678
447
2.2
35
68
1683
5220
Grand Total
210
2159
514
429
6903
-------
28
Meno'ocino
0 10 20
miles
SAN FRANCISCO
BAY AREA
Figure 10. Major Point sources in the San Francisco Bay Area.
-------
29
contributing slightly over 60 percent of the total emissions. The dense
distribution of freeways and expressways, (fig. 8), and major point sources,
(fig. 10), immediately surrounding the San Francisco Bay indicate that the
majority of air pollution from each county is emitted from locations near
the San Francisco Bay.
Air Quality and Meteorological Description
The study of air quality levels and a description of its behavior in
the atmosphere above the San Francisco Bay Area is necessary to determine
the magnitude and the geographic extent of the air pollution problem. This
type of evaluation should provide the necessary insight to assist in the
determination of the air quality control region boundaries.
Terrain features and land-sea breeze contrasts play very important
roles in the frequently observed air stagnation conditions, air flow patterns,
mixing depths, and diffusion potentials, and thus directly affect the air
pollution concentrations and distributions in the San Francisco Bay Area.
One frequently-used measurement of the concentration of photochemical
air pollution is total oxidant.* Notable oxidant concentrations are prevalent
in San Francisco Bay Area. In the presence of ultraviolet light, hydro-carbons
and oxides of nitrogen, the latter two, products of the automobile exhaust,
react to form photochemical air pollution.
Many meteorological factors directly affect the development and
accumulation of oxidants. Sunshine and temperature in particular affect
*Total oxidant is defined as the total of all substances that are capable
of oxidizing the iodide ion to iodine under certain specified conditions. The
concentration of total oxidant is approximately correlated with the eye-
irritating characteristic of photochemical smog.
-------
30
photochemical development, whereas temperature inversions and wind speed
affect pollutant accumulation in the local atmosphere. Ventilation index
values, based on the hourly rate of available air flow through an arbitrary
cross wind area under an inversion lid, have been computed regularly for
the BAAPCD since 1962." July, August and September are consistently the
months with most restricted ventilation, resulting from persistent
maritime inversions which limit the vertical pollutant dilution. Invariably,
the low ventilation indexes coincide with high oxidant values.
Figure 11 shows a 1967 seasonal average, (July-September), of daily
one-hour maximum, Computed from monthly averages of daily one-hour maximum values),
concentrations of oxidant for nine BAAPCD stations and the surrounding
stations. Table 3 presents the number of adverse oxidant days by county
from 1963-1967. Adverse is defined by the California State Department
of Health as days when readings of .15 parts oxidant per million parts of
air, (by the potassium iodide method), or higher, are attained for one
hour or longer. Adverse is considered the level at which there will be
sensory irritation, damage to vegetation, reduction in visibility or
8
similar effects. It is evident that significant oxidant levels do exist
in the valley portions of the present six county BAAPCD. Although there
are no recorded values of oxidant in the three northern counties (Sonoma,
Napa, and Solano), their valleys are condusive to air stagnations and the
photochemical smog reaction. Because these valleys complete the air
basin shared by the valleys of the Southern six counties, there is
undoubtedly potential for exchanges of air pollution within this basin.
This will be discussed in the following section.
-------
31
TABLE 3.
NUMBER OF ADVERSE OXIDANT DAYS BY COUNTY, 1963-1967.5
1963
17
5
2
3
8
22
1964
26
4
1
11
10
13
1965
27
11
4
4
23
34
1966
14
8
3
2
12
16
1967
14
17
4
3
15
19
COUNTY
Alameda
Contra Costa
Mar in
San Francisco
San Mateo
Santa Clara
Since the automobile is the number one source of pollutants in the
9
District , the annual distribution of carbon monoxide concentrations is
presented in figure 12, (values are also computed from monthly averages of
the highest average hour per day). Higher CO concentrations are related
to areas of dense traffic routes, figure 8, page 22.
Suspended particulate levels show a 1967 annual average of 97yUg/m
- 3
for Oakland, 76i4g/nrs for San Francisco, and 75yMg/m for San Jose.
Visibility restriction due to air pollutants from the Oakland
airport show increased number of days in the late fall and early, winter
where the visibility was 6 miles or less (Table 4).
*Visibility restriction is defined by visibility of 6 miles or less
with relative humidity below 70%.
-------
32
Meno'ocino
10 20
miles
SAN FRANCISCO
BAY AREA
*=Station
location
Figure 11. Seasonal (July-Sept) oxidant (KI) concentrations, PPM,
(seasonal average of daily one-hour maximum concentrations).
-------
33
Mena'oci no
10 20
miles
SAN FRANCISCO
BAY AREA
*=Station
location
Figure 12. Mean annual carbon monoxide concentrations, PIM, (yearly
average of daily one-hour maximum concentrations).
-------
34
Table 4. Number of days/month when visibility is 6 miles or less.
(Aug., 1967-July, 1968)
Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June July
35 10 14 4 12 463 103
Air Flow Patterns and Mixing Depths
Topography plays a major role in directing or restricting air flow
and hence the transport of pollutants in the San Francisco Bay Area. Since
most of the air pollution sources and receptors are located in the lowland
areas around San Francisco and San Pablo Bays, the Carquinez Strait and
in the Petaluma, San Ramon, Livermore and Santa Clara Valleys, the major
concern is how air flows from one of these sections to another or possibly
outside of the general area.
Trajectory analyses has frequently used by meteorologists to
demonstrate how air moves from one area to another. A number of reports
.1 2-20
deal with air flow patterns of the San Francisco area and general vicinity.'
In general these reports support one another in their descriptions of air
flow patterns. However, no single report is complete or detailed enough
to form a basis for this report.
The San Francisco area experiences seasonal and diurnal variations
in air flow the greatest seasonal difference is between winter and summer
and the most marked diurnal variation occurs in winter. The autumn and
spring are transitional periods during which the changes between seasonal
extremes of prevailing flow patterns occur gradually.
-------
35
Figures 13 and 14 (which are taken from Root 15), present the
prevailing daytime air flows which accompany the two most common
meteorological conditions in summer. Winds may approach the San Francisco
area from any direction but the vast majority have a westerly component.
The air is channeled through the passes and straits and along the sides
of mountains as it penetrates the coast at (1) the Esteros Lowland, (2)
the Golden Gate Pass, (3) the San Bruno Gap and (4) the Crystal Springs
Gap (See Figure 4). Even though there is considerable exchange of air and
thus pollutants between the portions of the nine counties tied into the
San Francisco and San Pablo Bays, only a limited amount of the incoming
air at the surface along the coast remains at the surface in its travel
to the Central Valley (the Valley east of the Vaca Mountains and Diablo
Range). Most of the air moves upslope on the west sides of the mountains
and remains aloft as it passes over the Central Valley. The only coastal
air that readily flows into the Central Valley at the surface and thus
capable of transporting pollutants at ground level, is restricted by the
topography to the circuitous route through the Golden Gate Pass and then
the Carquinez Strait. Thus some of the air from the Bay Area moves into
western Sacramento and San Joaquin Counties in the Great Central Valley
via this route. A greater(area is considered in a Stanford Research
18
Institute report and the indication is that very little air moves out
of nine county Bay areas to the north or south.
In another area, it appears that passage through the Golden Gate,
San Francisco Bay, Hayward Pass and Livermore Valley would bring air to
the Central Valley at the surface. Passage out from the Livermore Valley
is through a pass (Altamont) at an elevation of 750 feet, thus little,
-------
36
Mendocino
-.Conlro "'..
':'•• '-.Cojla
10
miles
SAN FRANCISCO
BAY AREA
^Surface
temperatures
*
Contour
Figure 13. Generalized afternoon flow pattern of
marine air in the San Francisco Bay Area under typical
summer conditions. The observed temperatures at 1630 PST
are entered to illustrate the cooling effect of the sea
breeze. (adapted from Root")
-------
37
Mendocino
miles
SAN FRANCISCO
BAY AREA
Contour
Figure 14.Generalized afternoon flow pattern
in the San Francisco Bay Area under conditions of
strong northwesterly flow, (adapted from Root!-*)
-------
38
if any, of the flow gets down to the central valley floor on the eastern
side of the Diablo Range.
Land and sea breeze effects are also important due to their air
pollutant transport capability. In many coastal locations throughout
the world a land breeze (flow from land to sea) occurs at night. That
this is not the case in the San Francisco area in summer is well
documented,13' 15' 17
Frenzel concludes, "any land-breeze effect is only to reduce the
nighttime velocity but not to reverse the direction." Thus the nocturnal
air flows are similar to those which occur in the daytime. The main
difference is that the volume of air moved from sea to land is reduced.
In the daytime in winter there is often an onshore flow. Root (1960)
notes, "- . .the driving northwest winds diminish and the prevailing
onshore flow is reduced to a gentle breeze...". The flow is similar to
that shown in figure 13 except that the volume of air moved is reduced
markedly. Smalley (1957) found that in the daytime in winter, flows from
all four quadrants frequently move into the San Francisco area; these
flows are readily channeled through the passes and straits and along the
sides of mountains. These variations of flow imposed by topography have
little effect in altering the mutual dependence of the individual counties
for air quality; all the counties of the Bay Area use and reuse much of
the same air.
The nighttime flows in winter, as typified in Figure 15, show air
movements that would be expected with land breezes (flow from land to
sea) superimposed on nocturnal mountain (flow downvalley in mountainous
or hilly terrain) winds. These flows are practically the reverse of
-------
39
Mendodno
0 10
miles
SAN FRANCISCO
BAY AREA
Figure 15 . Predominant January mean circulation of the
surface winds, (adapted from SRI1**)
-------
40
those which occur during typical summer conditions (see figure 13) .
The flow patterns also indicate that some air from Sacramento and San
Joaquin Counties flows into Contra Costa County.
Mixing depth, the vertical distance through which convective and/or
mechanical mixing of the air readily occurs, is one parameter used to
assess the air pollution potential of an area. Table 5 shows mean mixing
18
depth values considered representative of the San Francisco Bay Area.
These values and particularly those of the afternoon are markedly lower
21 22
than the national average, ' and indicate there is restricted vertical
mixing, or a limited volume of air available for dilution, compared to
many other sections of the country. Together with frequent light wind
speeds, these data indicate a relatively high pollution potential for
the Bay Area.
£
Table 5. Mixing Depths (meters), Oakland, California.
Morning
Afternoon
Average***
Summer
515
643
579
Winter
386
649
518
Annual**
517
781
649
*1 meter=3.28 feet
** four seasons
*** of morning and afternoon
Terrain and maritime influences have <± marked effect on the vertical
temperature distribution, and, therefore, the thermal stability of the area.
As an example, Figure 16 shows the spatial variation in the height of the
inversion which existed on a summer day when the inversion base was low.
The base is lowest over the Bay, rises over the land, and generally is
higher over the higher terrain.
-------
41
Mendocino
10 20 {:j*Qo
miles
SAN FRANCISCO
BAY AREA
Contour
Figure 16. Inversion base topography (feet),
0700-0900 PST, 16 Aug. 1966. (Constructed from
airplane soundings and radiosondes.) (adapted
from Miller23).
-------
42
Diffusion Potential
24
In a tracer study conducted by the Bay Area APCD, it was found
that, "pollutants released in any part of the Bay Area may travel to
virtually any other part under suitable meteorological conditions."
An additional conclusion was that measurable concentrations of the
material released could be detected 50 to 60 miles from their release
point.
Slade^S foun(j that dilution over a large body of water is markedly
less than over land so that the water separation of counties by the Bay
affords little benefit in regards to air pollution potential.
Prevailing air flow patterns over the Bay Area indicate that very
little pollution originating in the Area is transported out of the
region to the north or south. However, since some of the surface air
from the Bay Area moves out into San Joaquin and Sacramento Counties
through the Carquinez Strait, an analysis of the dilution climate of
the Central Valley region is offered. Table 6 shows average afternoon
mixing depths for Oakland and Fresno, which are considered representative
18
of the Central Valley. The indication is that there is considerably
greater vertical mixing in the Central Valley in all seasons but winter.
s
Table 6. Afternoon Mixing Depths (Meters) Fresno and Oakland.
Season Fresno Oakland
Winter 618 649
Spring 1767 1087
Summer 1765 643
Autumn 1221 745
-------
43
12
Fosberg and Schroeder noted that Bay Area air penetrated to
Sacramento and San Joaquin counties but that it was rapidly modified
as it preceded eastward and could only be recognized by its dew point
14
temperatures even in western sections. Patton showed that an air
mass starting just west of the Golden Gate at noon or midnight, during
the summer, would take approximately eight hours to get to the Central
Valley at the surface. The net result of the long travel time and
increased dispersion over the inland area during the convective daytime
period results in relatively good dilution of Bay Area pollutants by
the time they reach the Central Valley area.
In winter the flow is usually from San Joaquin and Sacramento
counties. However, this flow is generally weak and seldom persists for
an extended period, so there is only a limited possibility of pollution
in high concentrations moving from the Central Valley into the eastern
Bay Area.
Conclusion
On the basis of this evaluation, it is concluded that practically
all of the receptors that could be affected tfy high concentrations of
1
pollutants from the Bay Area are contained within the nine counties.
These nine counties are the logical, meteorologic boundary for the San
Francisco Bay Air Quality Control Region.
-------
44
REFERENCES
1. "Preliminary Regional Plan for the San Francisco Bay Region."
Association of Bay Area Governments; Berkeley, California.
November, 1966. 52 pp.
2. "San Francisco Bay Area Deep Water Channel and Inland Ports."
Conway Research, Inc. Industrial Development; San Francisco,
California. November, 1966. 52 pp.
3. Salitone, Edward V. and Evelyn D. Salitone. "California Information
Almanac. Past Present Future." Doubleday Company, Inc., Garden
City, New York, 1965. 624 pp.
.4. Bay Area Facts. San Francisco Bay Area Council, San Francisco,
California. January, 1968. 4 pp.
5. "Air Pollution and the San Francisco Bay Area." Bay Area Air
Pollution Control District, San Francisco, California. July, 1968.
25 pp.
6. Martin, D. 0. and J. A. Tikvart, "A General Atmospheric Diffusion
Model for Estimating the Effects of One or More Sources on Air
Quality" Paper (no. 68-148) presented at Annual Meeting, Air
#
Pollution Control Association, St. Paul, Minnesota, 1968. 46 pp.
7. "Oxidant Smog Experience in the San Francisco Bay Area, 1962-1967."
Bay Area Air Pollution Control District, Information Bulletin,
February, 1968. 13 pp.
8. "California Standards for Ambient Air Quality and Motor Vehicle
Exhaust." California State Department of Public Health; Berkley,
California. September, 1963. 25 pp.
-------
45
9. "Source Inventory Summary, 1964." Bay Area Air Pollution Control
District, San Francisco, California.- July, 1965. 12 pp.
10. Clean Air Quarterly. Bureau of Air Sanitation. State Department
of Health, 11:2:19-20, 1967; 11:2:23-24, 1967; 11:2:27-28; 12:1:28-29;
Berkley, California
11. "Contaminant and Weather Summary", Bay Area Air Pollution Control
District, San Francisco, California, (monthly report), August, 1967
to July,v 1968.
12. Fosberg, M. A. and M. J. Schroeder. "Marine Air Penetration in
Central California." Journal of Applied Meteorology, 5:5:573-589,
1966.
13. Frenzel, C. W. "Diurnal Wind Variations in Central California.
Journal of Applied Meteorology 1:3:405-412, 1962.
14. Patton, C. P. "Climatology of Summer Fogs in the San Francisco
Bay Area." University of California Publication in Geography,
10:113-200, 1956.
15. Root, H. E. "San Francisco, the Air-Conditioned City. Weatherwise,
13:47-52, 1960.
16. Schultz, H. B., N. B. Akesson, and W. E. Yates. "The Delayed "Sea
t
Breezes" in the Sacramento Valley and the Resulting Favorable
Conditions for Application of Pesticides." Bulletin of the American
Meteorological Society, 42:10:679-687, 1961.
17. Smalley, C. L. "A survey of air flow patterns in the San Francisco
Bay Area." Preliminary Report. U. S. Weather Bureau, International
Airport, San Francisco. March 1, 1957. (unpublished).
-------
46
18. "The Use of Meteorological Data in Large Scale Air Pollution Surveys,"
SRI Report for State of California, Bureau of Air Sanitation,
Berkley, California, 1958. 110 pp.
19. Williams, W. A. and R. E. DeMandel. "Land-sea boundary effects
on small circulation." Report #2, San Jose State College Meteorology
Department, State, 1966 97 pp.
20. Fitzwater, M. D. "The Summer Diurnal Influx of Marine Air into
the Sacramento Valley." PhD thesis, University of California at
Davis, 1966. 148 pp.
21. Holzworth, G. C. "Mixing Depths, Wind Speeds and Air Pollution
Potential for Selected Locations in the United States." Journal
of Applied Meteorology, 6:6:pp., Dec. 1967.
22. Hosier, C. R., "1963-4 Climatological Estimates of Diffusion
Conditions in the United States." Nuclear Safety, 5:2:184-192,
Winter year.
23. Miller, A. "Wind Profiles in West Coast Temperature Inversions"
Report No. 4, San Jose State College Meteorology Department,
State, 1968. 57 pp.
24. Callaghan, D. J. Memorandum to Sam Delia Maggiore, Chairman and
Members of the Board of Directors, Bay Area Air Pollution District
on the subject "Tracer Trail Program." August 7, 1968. 21 pp.
25. Slade, D. H. "Atmospheric Dispersion over Chesapeake Bay", Monthly
Weather Review 90:6:217-224, 1962.
ft U. S. GOVERNMENT PRINTING OFFICE : 1989 3Ui-61a (5007)
------- |