-------
Ur.ited States * Region 10 il0"
Environmental Protection 1200 Sixth Avenue December 1978
Agency Seattle. WA 98101
Part 1
Carbon Monoxide Study
Seattle, Washington
October 6 - November 2, 1977
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EPA 910/9-78-0f4a
Part 1. CARBON MONOXIDE STUDY - SEATTLE, WASHINGTON
OCTOBER 6 - NOVEMBER 2, 1977
EXECUTIVE SUMMARY
PREPARED 8Y
C. 5. Wilson and J.W. Schweias
SURVEILLANCE AND ANALYSIS DIVISION
FOR
AIS PROGRAMS BRANCH
AIR AND HAZARDOUS MATERIALS DIVISION
U.S. ENVIRONMENTAL PROTECTION AGENCY, REGION 10
1200 SIXTH AVENUE
SEATTLE, WASHINGTON 96101
DECEMBER 1978
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DISCLAIMER
This Report has been reviewed by Che Environmental Protection Agency Region
10 and is approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Env'ronmental
Protection Agency nor does mention of trade names or conmercial products
constitute endorsement or recomnendstion for use.
ii
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PREFACE
Under Che Clean Air Act of 1970 Che U.S. Environmental Protection Agency has
established standards for carbon monoxide in air external to buildings to
which the public has access. In a number of cities, including Seattle,
these standards have not jet been attained. Plans to achieve the standards
are nov required under the Clean Air Act Amendments of 1977 (PL 93-95). It
is hoped that the material presented in this report will assist in achieving
attainment of the standards.
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ACKNOWLEDGMENTS
We gracefully acknowledge Che assistance of members of Che Washington Staca
Department of Ecology (DOE), the City of Seattle, and the firms and insti-
tucions which permitted installation of equipment cn their premises. With'
our their cooperation, portions of chis study could not have been conducted
Our sincere thanks go to Che National Park Service, Seattle First National
Bank (Seaboard Branch), the Central Hotel, Singer's, and the Bracken Phar-
macy. Finally, we express gratitude to many members of the EPA staff for
guidance, ei couragement, and assistance.
iv
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TABLE OF CONTENTS
Page
Preface iii
Acknowledgments iv
Table of Contents v
List of Figures vi
List of Tables vii
Abbreviations and Symbols viii
INTRODUCTION 1
SUMMARY 1
CONCLUSIONS AND RECOMMENDATIONS 4
METHOD OP STUDY 11
RESULTS AHD DISCUSSION 15
Outdoor Sites 15
Indoor Sites 27
Pedestrian Routes 29
v
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LIST OF FIGURES
Figure Page
1 Outdoor Sampling Locations 12
2 Characteristics of Weekday Carbon Monoxide Average Concentrations
for an 8-Hour Period at Each Site 18
3 Maximum 8-Hour Values for Entire Sampling Interval 20
4 Frequency of 8-Hour Values Greater than 9.0 PPM 21
5 Second-Highest 8-Hour Values for Entire Sampling Interval 24
6 Day of Highest Average Over All Sites 25
7 Characteristics by Day of the Composite Range of Carbon Monoxide
Concentrations for All Sites During an 8-Hour Period 26
vi
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LIST OF TABLES
Table Page
1 Seattle Carbon Monoxide Outdoor Sampling Sites 13
2 Maximum Values from Thirty-six Sites and the Permanent Monitors . 16
3 Comparison of Maximum Study Site and Permanent Monitor Eight-Hour
Averages 28
VI i
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Abbreviations and Symbols
AM - The four-hour interval from 10:00 a.m. to 2:00 p.m.
PM - The four-hoar interval from 2:00 p.m. to 6:00 p.m.
AVC - The eight-hour average CO concentration for the 10:00 a.m. to
6:00 p.m. sample collected at an EPA special study site
AVSxxx- The eight-hour average CO concentration for the 10:00 a.m. to
6:00 p.m. period from continuous non-dispersive infra-red (NDIR)
measurements at a permanent monitor where "xxx" is an abbreviation
for the particular monitor
s/o - "South of" as in Second Avenue s/o University Street
e/o - "Eaat of" as in James Street e/o Fourth Avenue
R.AVC.AVS^. - Ratio of eight-hour averages at the same time for a
study site and for a permanent monitor (where "x" is the first
letter abbreviation of the abbreviations listed below)
JAM - Permanent monitor on James Street (north side) e/o Fourth Avenue
(the Municipal Building)
UNI - Permanent monitor on Second Avenue (weat side) s/o University
Street (near McPhearson's Leather Co.)
PIK - Permanent monitor on Fourth Avenue (east side) s/o Pike Street
(Fourth and Pike BuildLng)
SIN - Permanent monitor on Pike Street (south side) e/o Fourth Avenue
(near Singer'n)
FIR - Permanent monitor on Second Avenue (west side) s/o Main Street
(Fire Station No. 10 near Pioneer Square)
Exceedence of Standard* - An eight-hour average CO concentration exceeding
9.0 ppm
Violation of Standard - The second eight-hour, non-overlapping, running
average CO concentration in a year to exceed 9.0 ppm
* This report discusses only the standard for the eight-hour average and
does not discuss the standard for one-hour average CO concentrations.
viii
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INTRODUCTION
Frequent violations of the national ambient air quality standard* for
eight-hour average carbon monoxide (CO) concentrations nave occurred at
several of the continuous monitors operated in downtown Seattle by the
Washington State Department of Ecology. However, more information on the
severity of the CO problem and its spatial distribution in the downtown
area was desired to assist in selecting candidate sites for additional
routine monitori.ig and evaluating the extent to which the permanent
monitors represent sites elsewhere in the central business district. The
levels of CO encountered by the population as downtown pedestrians and as
indoor occupants were also of interest. A study was planned and conducted
to address these needs. This report (Part 1) presents the major results
and conclusions. A more detailed description of the methods, additional
discussion and analysis and data obtained in this study appear in a
separate volume (Part 2).
In 1977, a 20-day study involving 36 outdoor sites, five indoor sites, and
two pedestrian walking routes was conducted in downtown Seattle during
* Standards for carbon monoxide which are not to be exceeded more than
once per year are 9.0 ppm (eight-hour average) and 35.0 ppm (one-hour
average). See 42 FR 8186, Federal Register, April 30, 1971.
SUMMARY
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Octo',er-November which is daring part of Che season when high carbon
monoxide levels frequently occur. The purpose of this study was to obtain
more information on the magnitude and spatial extent of the carbon
monoxide problem which would aid evaluation of the extent to which the
existing permanent monitors represent locations elsewhere in the central
business district and would assist in selection of candidate sites for
routine monitoring. On each week-day, two four-hour bag samples were
collected from about 10:00 a.m. to 2:00 p.m. (AM sample) and about 2:00
p.m. to 6:00 p.m. (PM sample) at 33 of the outdoor sites and two or three
of the indoor sites simultaneously. Technicians collected bag samples of
air on two pedestrian walking routes over two to four hours during the AH
and PM periods.
Data are summarized in bar charts of the measurement distribution for each
site and each day of the 3tudy period, in histogram-maps showing the
spatial distribution of carbon monoxide, and in tables. Results from the
study sites were compared in several ways with data from the permanent
monitors. Comparisons were also made between study sites along the same
corridor, between indoor sites and adjacent outdoor sites, and between the
two pedestrian routes. Eight-hour averages were compared with the 9.0 ppm
standard.
The study results indicate that the carbon monoxide problem is net
restricted to the immediate vicinity of the permanent monitors in the
downtown commercial district. The permanent monitoring network was
2
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generally representative of the high concentrations but not Che highest
frequency of violations which occurred in Che study area. More frequent
exceedences of Che standard occurred on Sixth Avenue south of Union
(site 19) than at any of the permanent monitoring sites during this
study. CO values exceeded the 9.0 ppm eight-hour standard at some study
sites on days when the highest eight-hour average of the permanent
monitors measured on that day was (1) below the standard and (2) less than
two-thirds of the highest average observed at the maximum study site on
chat day. Increases in carbon monoxide at indoor sites frequently
coincided with increases at outdoor sites. At times, some of the indoor
population was exposed to eight-hour average concentrations above 9.0 ppn,
which is the outdoor standard.
Routine monitoring of peak concentrations should consider the monitoring
site on Fourth Avenue south of Pike Street. Planning for future stuuj.es
should consider the need for related data on traffic characteristics
coupled with meteorological data.
3
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CONCLUSIONS AND RECOMMENDATIONS
The major conclusions of a 20-day study conducted in Seattle during about
10:00 a.m. to 6:00 p.m. on week-days of October - November 1977 are:
1. The severity of the carbon monoxide problem in the central business
district as measured by the highest eight-hour average concentrations
(compared without regard to the day in which they occurred) was
adequately represented by the permanent monitor at Fourth Avenue south
of Pike Street. However, the permanent monitoring network did not
represent the highest frequency of exceedences of the eight-hour
standard during the twenty-day period.
During the study period, the highest 10:00 a.m. to 6:00 p.m.
average of all the study sites was 16.1 ppm and it occurred on
October 28 at site 1 on First Avenue south of Pike Street. This
was essentially the same as the highest of all the permanent
monitors during the study period (15.8 ppm on October 14th at
PIK, the permanent monitor on Fourth Avenue south of Pike Street).
About 17Z of the study sites (6 out of 36) experienced at least
one eight-hour average concentration within 2.0 ppm of the
highest 10:00 a.m. to 6:00 p.m. average of all the permanent
monitors. (Note that these are comparisons of ti.e maximums
during the 20-day study period and did not necessarily occur on
the same day.)
U
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The highest eight-hour average at each of these six study sites
(sites 1, 5, 7, 9, 10, and 19) exceeded the maximum at the Second
and University monitor, 12.8 ppm, which was the next highest
reading from a permanent monitor. (Again, this comparison is of
maximums during the 20-day study period, regardless of the day on
which they occurred.)
2. The permanent monitoring network was not representative of the highest
frequency of exceedences of the 9.0 ppm standard within the study area
for this twenty-day period.
The eight-hour standard vaa exceeded at one or more study sites on
80Z of the study days (16 out of 20). Exceedences at one or more
of the permanent monitors occurred on 45Z (9 out of 20) of the
sampled days.
The most frequent exceedences of the 9.0 ppm standard were observed
at site 19 on Sixth Avenue south of Union Street (802 of the
days). Considering all study sites, this site had the highest
eight-hour average of the day more frequently than any other site
(on 6 of the 20 days of the study). The highest eight-hour average
at site 19 over the twenty-day study interval (13.9 ppm on
October 28) was exceeded at only four study sites. These sites (1,
7, 9, and 10) also experienced their highest values of the
twenty-day interval on October 28 (16.1, 14.5, 14.0, and 1V0 ppm,
respectively).
5
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The frequency of exceeriences at Che permanent monitors ranged from
OZ at Che Fire Station on Second Avenue south of Main Street (FIR)
to 40Z of the sampled days at the monitoring site on Fourth Avenue
south of Pike (PIK).
On all but two days, the highest eight-hour concentration of those
measured at the permanent monitors for 10:00 a.m. to 6:00 p.m. was
exceeded by that at one or more study sites.
During Che survey, the second-highest eight-hour average for
10:00 a.m. Co 6:00 p.m. for any permanent monitor (13.6 ppm on
10/28/77 at PIK on Fourth Avenue south of Pike Street) was exceeded
by one study site's second-highest average (15.0 ppm on 10/21/77 st
site 10 on Fourth Avenue south of Union).
3. The CO problem occurred throughout the downtown connercial district but
concentrations were lower at some locations.
For 47Z of the study sites (17 of 36), the 10:00 a.m. to 6:00 p.m.
eight-hour average exceeded the 9.0 ppm standard more Chan once.
For 14Z of Che study sites (5 out of 36), the 10:00 a.m. Co
6:00 p.m. eight-hour average equalled or exceeded Che 9.0 ppm
standard exactly once.
6
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For 39Z of the study si?es (14 out of 36) including some locations
in parks and other areas of expected low concentrations, eight-hour
averages for 10:00 a.m. to 6:00 p.m. did not exceed the 9.0 ppm
standard during the 20-day study.
The highest eight-hour average of the day did not always occur at
the same sites. On 90Z of the days (18 of 20), the highest average
was measured at a study site rather Chan at a permanent monitor.
Sites 1, 5, 7, 10, 19, 22, 29, and 36 were study sites which were
"mfi'imum" on at least one day considering permanent monitors as
well as study sites. Site 19 was highest on 35Z of the days and
tied for highest with PIK on 5Z of the days; each of the sites 1,
7, 10, and 22 was highest on 10Z of the days; and each of the sites
5, 29, aad 36 was highest on 5Z of the days. The permanent monitor
PIK, was highest on SZ of the days.
Relatively low average concentrations were observed at sites 18,
21, and 35 which are closer to the freeway than the other study
sites. For these sites, the averages of all eight-hour values vere
4.2, 3.8, and 3.6 ppm respectively.
On four of the days when no violations were observed at the
permanent monitors, the maximum study site's eight-hour average
exceeded 9.0 ppm and was more than 1.5 times greater than at the
maximum permanent mcnitor.
7
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When concentrations exceeded the standard at the permanent monitors
they were exceeded at a number of other locations.
4. Changes in CO concentrations at outdoor sites frequently coincided with
changes in CO concentrations at indoor sites, but the relationship
between indoor and outdoor values was not constant.
Concentrations were usually lower indoors than at the selected
adjacent outdoor site.
Indoors, the eight-hour average concentration of carbon monoxide
exceeded 9.0 ppm at one of the five aites (SIM 1) on Fourth Avenue
south of Union Street.
5. Pedestrians were probably exposed to average CO concentrations exceeding
9.0 ppm over four or more hours at tines.
For santpling periods between two to four hours, concentrations
ranged from 1.1 ppm to 11.9 ppo.
For sequential or nearly sequential sampling periods totalling two
to four or more hours, average concentrations were equal Co or
above 9.0 ppm on three of the 20 days. (On most days, sampling was
not conducted for a consecutive eight-hour interval on the
pedestrian routes as personnel were required for other duties.}
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It is reconmended that:
1. The carbon monoxide problem in downtown Seattle be considered an
areawide problem in the central business district, as opposed to a few
isolated "hot spots".
2. Increased local source emissions be avoided in areas where violations
have been observed unless a reduction in the background concentrations
which is more than sufficient to offset the increase and attain and
maintain the National Ambient Air Quality Standards can be demon-
strated.
3. Concentrations at the permanent monitoring netvork above 9.0 ppm be
considered as indicative of concentrations equally high and possibly
higher elsewhere in the study area at the same time. However,
concentrations at the permanent monitors below the 9.0 ppm standard on a
particular day should not be considered as assurance that air quality
standards are being met throughout the study area on that same day.
U. The permanent monitor on the east side of Fourth Avenue south of Pike
Street (PIK) be considered as a candidate site to represent peak carbon
monoxide concentrations in downtown Seattle for routine monitoring.
5. Planning for future studies to aid development and/or revision of
control strategies to attain the natural ambient air quality standard
should consider the possible utility of ancillary data on traffic and
meteorological characteristics to aid data interpretation.
9
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METHOD OF STUDY
Thirty-six outdoor sites (Figure 1 and Table 1) were selected after a
review of traffic characteristics, potential population exposure, and
planning information for the Seattle downtown area. Sites cere selected
to yield data on a variety of locations throughout the central business
district. However, sites were not allocated to represent proportionated
the land or population of the various portions of the study area. Thus,
certain characteristics of data from the study sites, such as the
percentage of sites where low CO values were found, should not be
interpreted to imply that a similar percentage of the land or population
in the study area experienced such values.
Traffic volumes were a significant factor in the selection of many sites
because the motor vehicle is by far the major source of carbon monoxide in
Seattle. However, locations where idling vehicles occur in situations
such as entrances or exits from large parking lots were deliberately
avoided. Some sites were chosen which were expected to yield low CO
values because of their ventilation or remoteness from cars. At each
site, the sample inlet was abcut 34 meters above the sidewalk, more than
10 meters from an intersection, and more than 2 meters from a vertical
wall. Host samples were a little over one meter from the street curb; two
were at much greater distances (in parks).
11
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PiCUr£ j
1-6
*V>»>
AL^:
S*»N
k"'«n Aw>
Seattle Carbon Monoxide Study
Location of EPA Sampling Sites
10/6/77 to i" "*
to H/2/ 77
O STATE SJT6S
O
SJT£S
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TABLE 1.
SEATTLE CO STUDY - Oct. 6 to Nov. 2, 1977
SITE IDENTIFICATION
SITE # LOCATION SIDE OF STREET
1 1st s/o Pike W
2 1st s/o Madison E
3 IsC s/o Washington E
4 2nd s/o Pine W
5 2nd s/o University W
6 2nd s/o University E
7 Jrd s/o Union W
8 4th s/o Pike W
9 4th s/o Pike E
10 4th s/o Union W
11 4th s/o Madison W
12 4th s/o Cherry W
13 4th s/o Lenora E
14 4th s/o Pine E
15 5th s/o Pine E
16 3rd s/o Cherry W
17 6th s/o Pine E
18 6th s/o Columbia W
19 6tn s/o Union E
20 Occidental s/o Washington S
21 9th s/o Union E
22 Olive e/o 5th S
23 Pike e/o 7th S
24 Pike e/o 4th S
25 Pike e/o 4th N
26 Pike e/o 3rd N
27 Pike w/o 1st S
28 Union e 'o 5th N
29 University e/o 5th S
30 Columbia e/o 1st N
31 James e/o 1st N
32 Alaskan Way s/o University W
33 Alaskan Way */o Madison W
34 James e/o 4th S
35 Seneca e/o 6th N
36 Pine e/o 5th N
PERMANENT MONITORS (STATE SITES)
JAM JAMES E/O 4TH N
UNI 2ND S/O UNIVERSITY W
3IN PIKE E/O 4TH S
PIK 4TH S/O PIKE E
FIR 2ND S/O MAIN v?
13
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Each week-day, air was collected into a bag during two sequential periods
(about 10:00 a.m. to 2:00 p.m. and about 2:00 p.m. to 6:00 p.m.) so that an
eight-hour average could be calculated for comparison vith the National
Ambient Air Quality Standard of 9.0 ppa which is not to be exceeded more
than once per year. Samples were obtained during October 6 through
November 2, 1977 on week-days from about 10:00 a.m. to 6:00 p.m. because
this period of the day seemed most likely to have high carbon monoxide
levels based on data from the permanent monitors. This period of the day
appeared to be fairly representative of the highest eight-hour
concentrations since the daily maximum eight-hour averages at the James
Street and the Fourth and Pike state monitors (JAM and PIK) were usually
within 1 ppm of the 10:00 a.m. to 6:00 p.m. average during the days of the
study. Carbon nonoxide in the study samples was analyzed by an electro-
chemical oxidation method, (Ecolyzer). Continuous analysis of air at the
indoor sites (in addition to bag sampling indoors and sl the adjacent
outdoor site) monitored the daily pattern of indoor carbon monoxide levels.
Indoor sites representing exposure situations in downtown buildings within a
few blocks cf the permanent monitors at Pourth and Pike included a small
retail shop, a hotel, two office buildings and a medical building. At all
locations, care was taken to avoid non-vehicle sources of carbon monoxide
such as tobacco smoke in the ionediate vicinity of the sampler or fuel
combustion from building heating systems. The nearest adjacent outdoor site
was the basis for comparison.
U
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RESULTS AND DISCUSSION
Outdoor Sites
The relative severity of the carbon monoxide problem at various outdoor
3ites during the selected time period is indicated by several measures.
Maximum and second-highest eight-hour averages, the frequency of exceedences
observed at each site and maximum four-hour AM (10:00 a.m. to 2:00 p.m.) and
PM (2:00 p.m. to 6:00 p.m.) averages in Table 2 may be compared with values
based on measurements at the permanent monitoring sites. Data distributions
for each site's eight-hour (10:00 a.m. to 6:00 p.m.) averages are compared
in Figure 2. Figures 3, 4, and S illustrate the spatial variation of the
data in Table on maps of Seattle.
In general, the lowest eight-hcur values occurred at the sites adjacent to
Elliot Bay (sites 32 and 33), and ths park sites (sites 20 and 35). The
relatively good ventilation possible in these areas and, in the case of the
park sites, the greater distance from the nearest roadway may have contri-
buted to the lower concentrations at these sites.
Depending on the purpose of the analysis, different measures are appropriate
for examination of the representativeness of the existing permanent
monitoring network. Day-by-day similarities are not required to compare the
necessary reduct.on of carbon monoxide levels implied by data from two
different sites. The relationships between data at the permanent monitors
and at other sites are not necessarily the same from day-to-day.
15
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Si te
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Table 2. Maximum Values from Thirty-Six Sites and Five Permanent Monitors
(Carbon Monoxide in PPM)
Maximum AM Maximum PM Maximum AVC X AVC Ratio.I1' Ratio.1 Ratio.1 Ratio.1 Ratio.1
10 AM — 2 PH 2 PM - 6 PM 10 AM - 6 PM CT 9.0 Jamee Univeraity Singer Pike Fire Station
12.4
19.9
16.1
33.0
-
1.3
1.3
1.2
2.5
11.9
8.0
7.4
0.0
-
-
0.9
1.0
-
13.8
13.6
11.0
11.0
-
0.9
0.9
0.8
1.7
10.6
13.0
11.8
22.0
-
0.9
1.0
0.9
1.8
17.0
14.9
13.7
35.0
-
-
1.6
1.8
-
7.8
8.7
7.9
0.0
0.8
1.8
1.3
0.7
_
16.8
12.2
14.5
57.0
-
1.1
1.2
1.1
2.8
10.9
14.5
10.4
19.0
2.2
1.0
l.l
0.9
-
10.9
17.1
14.0
32.0
-
1.1
1.1
1.0
2.1
14.4
17.8
15.0
33.0
-
1.2
1.2
1.1
2.3
12.6
12.0
11.4
26.0
1.2
1.6
1.7
-
2.3
10.0
10.5
10.3
7.0
-
0.8
0.8
0.8
1.6
8.0
9.0
7.0
0.0
0.6
1.1
1.2
0.4
-
6.5
8.1
7.3
0.0
-
0.6
0.6
0.5
1.1
11.0
11.1
10.3
6.0
-
0.8
0.8
0.8
1.6
10.4
11.5
10.0
17.0
1.7
0.9
1.1
1.0
1.7
15.4
12.8
12.0
47.0
-
-
1.4
1.6
-
7.5
7.8
7.4
0.0
-
0.6
0.6
0.5
1.1
13.6
15.9
13.9
80.0
-
1.1
1.1
1.0
2.1
5.5
5.2
4.4
0.0
-
0.3
0.4
0.3
0.7
8.0
6.1
7.1
0.0
-
0.6
0.6
0.5
1.1
13.7
18.6
11.2
26.0
-
-
1.3
1.6
_
12.9
14.0
11.4
U .0
2.4
1.0
1.2
1.0
_
10.7
12.0
10.7
12.0
-
0.8
0.9
0.8
1.6
12.0
9.1
9.3
5.0
-
0.7
0.8
0.7
1.4
8.0
10.9
8.6
0.0
0.8
1.4
1.5
0.5
0.8
7.7
9.5
8.5
0.0
1.8
0.8
0.9
0.7
-
10.1
13.0
10.2
27.0
0.9
1.6
1.7
0.6
_
11.0
14.1
10.4
5.0
-
0.8
0.8
0.8
1.6
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Table 2. (continued)
Si te
30
31
32
33
34
35
36
jam!/
UNll/
SIN*/
Pllti/
FIR®./
Maximum AM
10 AM - 2 PM
Maximum PM
2 PM - 6 PM
Maximum AVC
10 AM - 6 PH
X AVC
GT 9.1
7.0
9.0
7.9
0.0
7.1
7.9
7.2
0.0
5.5
5.2
5.4
0.0
5.0
4.5
4.6
0.0
9.3
11.9
10.3
6.0
7.8
5.5
5.7
0.0
11.6
12.9
11.4
41 .0
10.0
12.3
11.1
27 .0
11.0
14 .5
12.8
15.0
10.8
13.8
12.3
16.0
13.5
18.0
15.8
40.0
6.0
7.8
6.5
0.0
Ratio. \\J.
James—
0.7
1.0
0.6
0.5
1.2
1.0
1.4
Ratio.1 .Ratio.I . Ratio. 1.
University— Singer— Pike—
1.3
0.8
O.fl
0.7
0.8
1.6
1.8
1.0
1.0
2.5
0.5
Ratio.1
6 A
Date of
Fire Station— Maximum AVC
1.3
0.5
-
10/14/77
-
0.8
1.2
10/28/77
0.8
-
1.1
10/10/77
0.7
-
0.9
10/10/77
0.8
0.8
1.6
10/28/77
0.7
0.7
-
10/27/77
1.7
-
2.3
10/10/77
1.9
0.7
-
10/14/77
1 .0
0.9
2.0
10/28/77
1.0
0.9
1.9
10/28/77
2.7
1.0
-
10/14/77
0.5
0.5
1 .0
10/28/77
Footnotes
1. Ratio.1 - Ratio of the maximum eight-hour average at the study site to the eight-hour average at the sane time
(and day) at the permanent monitor.
2. Permanent monitor on James Street east of Fourth Avenue (JAM).
3. Permanent monitor on Second Avenue south of University Avenue (UNI).
4. Permanent monitor on Pike east of Fourth Avenue (SIN).
5. Permanent monitor on Fourth Avenue south of Pike Street (PIK).
6. Permanent monitor on Second Avenue south of Main Street (FIR).
NOTE: Eight-hour averages for the permanent monitors were calculated from hourly averages (eight values). No
estimates were made for missing data.
-------
Seattle Carbon Monoxide
October 6 to November 2, 1977
(Weekdays Only)
FIGURE 2
Characteristics ofWeekday Carbon Monoxide Average Concentrations for
an Eight-Hour Period (10:00 A.M. to 6:00 P.M.) at Each Site.
20.0-r
1
JL
2
i
ft
Ui
r
H
n
A
o
1
6
T
A
O
Icl
T
m
r
a
r
1
2
2
l-l
n
YT
1
2
T
A
10 11 12 13 14 IS 16 17 18 19 20
* / / * / / / * * / / / / / / / / i
S I / * i / / / f >• / >• 3 i
/ i Z } * ' / * # •? s- «
* rf -C ®
//
4
s
18
-------
Manmum
2nd hiQhaat
Man ~ ana
Median
T.
Maan - ona «and»rt dawation
Minimum
» Sltaa - Hnt 10 day*
•• Sltaa - last 10 days
Standard not to ha iinadart mora than onca par yaar
21*
2* 25 » 27 28 29 » 31 32* 33* 34 35" 36 JAM UNI SIN PIK FIR
/ £ # v5 £ .? «? £ ¦? S f / # # £ * / * / /
/ / * * i *'////:!//'/ / ' ' /
/ / *• " i
SITE NUMBER
/ /
19
New Nufnftar of i
-------
FIGURE 3
0 Denotes 20-Day Sites (10/6/77 - 11/2/77)
| Denotes First 10-Day Sues (10/6/77 - 10/19/77)
| Denotes Last 10-Day Sites (10/20/77 - 11/2/77)
I
Black Denotes Values Greater
than 9 PPM CO
r .,•»»
•*\ . -
3 ^' \
. X
w
o
^••ILszr.' ip^
V
^ ,
- v.
•c* .
X t;
I
V" i «•
5
f
J
¦/*¦
^ .uJduA a. -i; *V •- ^
- 1'
*' X<~
Si-,
\ ^
HI IOI I HA\
f
to
Scale in PPM CO
jr' XivCARBON MONOXIDE
X V x CONCENTRATIONS
^ / 10/6/77 to 11/2/77
\/ SEATTLE CENTRAL BUSINESS DISTRICT
MAXIMUM 8-HOUR' VALUES FOR ENTIRE
SAMPLING INTERVAL Alkil ™ 0
10 AM TO 6 PM
-------
FIGURE 4
W Denotes 20-Uay Sues (10/6/77 - 11/2/77)
| Denotes First 10-Day Sites 110/6/77 - 10/19/77)
|| Denotes Last 10-Day Sites (10/20/77 - 11/2/77)
I Black Denotes Frequencies
Greater than 25%
< *
* Sites where frequency is 2 5% or less
•• -i » ' 1
^ >1
. o"r (i;
.A*.
v. -¦;>* - '-C ^ 'V„ ^
?> f r- akOfcl u«.
Lt"' IVA Y
:• ! MQR1H
* >" "'"St
r 100
50
¦^T «
CARBON MONOXIDE
H I/O I t /Ml
^ concentrations
. q Scale %
10/6/77 to 11/2/77
SEATTLE CENTRAL BUSINESS DISTRICT
FREQUENCY1 OF 8-HOUR2 VALUES GREATER THAN 9.0 PPM
'ROUNDED TO NEAREST 5% 210 AM TO 6 PM
-------
Because attainment of the national ambient air quality standard will depend
on developing and carrying out plans to reduce existing CO levels, it is
useful to know whether or not the higher CO levels are similar at sites when
measurements are taken over an extended period. Therefore, the maximum
eight-hour average concentration and the frequency with which it exceeded the
9.0 ppm standard at each site are appropriate measures for comparison.
On 80Z of the study days, the eight-hour standard was exceeded at one or more
sites. One of the study sites experienc£d an eight-hour average for 10:00
a.m. to 6:00 p.m. (16.1 ppm on October 28 ac site 1) that was approximately
the same as the highest observed at any permanent monitor during the survey
period (15.8 ppm on October 14* at PIX). Site 19 on Sixth Avenue south of
Union Street had the most frequent exceedences of the 9.0 ppm standard
(80Z of the sampled days) and most often had the highest 8-hour average of
all study sites (on eight days of the 20-day sample period).
Figure 4 shows that about 61Z of the sampling sites (22 out of 36)
experienced one or more days when the eight-hour average exceeded the
* On this day, data for site 9, which was nearly collocated with the
permanent monitor (PIK), indicated 12.4 ppm - 3.4 ppm less than at PIK.
However, this was atypical in that on most days data from the two sites
were within 1 ppm.
22
-------
9.0 ppia standard. The frequency of exceedences for four study sites (sites
7, 17, 19 and 36) was greater than for the highest permanent monitor (402 at
PIK). None of the four sites were on the same street as an existing monitor.
Figure 5 shows the second-highest eight-hour average at each site. During
the study period, the maximum second-highest AVC recorded for any site,
13.5 ppm at site 19, was essentially the same as the highest second-high
eight-hour average for 10:00 a.m. to 6:00 p.m. at any of the permanent
monitors, 13.6 ppm at PIK. Seventeen study sites experienced at least two
days with an eight-hour period averaging above the standard. These were
spread throughout the study area and included sites on Olive Way, Pine,
Pike, Union, First, Second, Third, Fourth and Sixth Avenue. Undetected
violations may have occurred at other sites or with greater magnitude at
these same sites during the days of the study.
On .
-------
figure; 5
fj Demotes 20-Day Sites (10/6/77 - 11/2/77) ..
| Donoies First 10 Dav Sites (10/6/77 - 10/19/77)
| Denotes Last 10 Day Sites (10/20/77 - 11/2/77) ?
Black Denotes Values Greater ,<• . , • » - ^
' ¦ ¦ ~k *» *> > V"*
+ r Y^'" --"^C JV'A .A
^ ^ .V^n -.r;4
i
than 9 PPM CO
> j*- ¦
¦ - ^ v- J
v r ¦
:v
CIDSNT^i
MMr
NOH1H
H I Id I I /< -M
r
••< - *
t) Scale in PPM CO
CARBON MONOXIDE
CONCENTRATIONS
10/6/77 to 11/2/77
SEATTLE CENTRAL BUSINESS DISTRICT
SECOND HIGHEST 8-HOUR1 VALUES FOR
ENTIRE SAMPLING INTERVAL ,
10AM TO 6 PM
-------
t IGUHE *>
Denotes 20-Day Sites (10/6/77 - 11/2/77)
Denotes First 10-Day Sites (10/6/77 - 10/19/77)
Denotes Last 10-Day Sites (10/20/77 - 11/2/77)
Black Denotes Values Greater
than 9 PPM CO
' S
V
v.
10
'
V
%
». #No monilonng daia lor these silos this date
* ¦, \ *¦
v' V*** >
* P V f
: \ -*K. n l. -» *
jh£""X| \
X ^ N*
• ' '-fr
f X»v
it .V *
-it.. 'ikL..
NORIH
' ¦ *; p^
H I lot I II l\
»¦ ' *
' c ^
Scale in PPM CO
CARBON MONOXIDE
CONCENTRATIONS
/* 10/6/77 to 11/2/77
SEATTLE CENTRAL BUSINESS DISTRICT
DAY1 OF HIGHEST AVERAGE OVER ALL SITES
'10 AM TO 6 PM 210/28/77
-------
Seattle Carbon Monoxide
October 6 to November 2, 1977
FIGURE 7
Characteristics by Day of the Composite Range of Carbon Monoxide
Concentrations for all Sites During an Eight-Hour Period.
<10:00 A.M. to 6:00 P.M.)
Maximum
Mean + one ftUftdard devteftort
O Mwlun
A Mean
-|J Mean - one tiandasd deviation
I — Minimum
• Standard not to be exceeded
more (hen once per year
200*i-
16 0 -
to 0-
90
60 -
-l.
-L.
J.
-J-
10/6 10/7 10/10 10/11 10/12 10/13 10/14 10/17 10/10 10/19 10/20 10/21 10/24 10/2b 10/26 10/27 TO/28 10/31 11/1 11/2
DATE (1977)
-------
On four of Che days when no violations were observed at Che permanent
monitors,* che maximum concentration at a study site was above 9.0 ppm and
more than 1.5 times greater than the highest concentration observed at a
permanent monitor. However, a concentration above 9.0 ppm at an/ of the
permanent monitors was usually accompanied by equally high or higher
concentrations elsewhere. The highest concentration for 10:00 a.m. Co
6:00 p.m. at Che permanent monitors was higher Chan at any ocher site on
only two days of Che sCudy (Table 3).
Indoor Sices
Ac all five indoor sices, Che concentrations were nearly always less and
never more Chan 1 ppm greater Chan at Che adjacent ouCdoor sites. AC one
sice (che firsC floor recail shop), che indoor CO concentraCion was usually
wichin one ppm of Che ouCdoor concentration. Otherwise, no consistent
relationship between indoor and ouCdoor levels was noCed in chis limited
study. The eighc-hour average concenCration between 10:00 a.m. to 6:00 p.m.
exceeded 9.0 ppm at one of che indoor locations with a maximum value of
10.1 ppm. At chis sice, late afternoon increases in indoor CO were
observed, suggesting an influence from the afternoon peak traffic.
On three of these days, data were incomplete for three or four of the
five permanent monitors.
27
-------
TABLE 3. Comparison of Maximum Study Site Each Day and Permanent Monitors by Eight-Hour Averages for 10:00 a.m. to
6:00 p.m.
(CO in ppm)
Max
Max
Max
Max ,
„ • 2/
Ratlo —
Rat io
Rat io
Rat io
Ratio
Rat io
1977 Dbte
Study Site AVC
Perm Hon
AVS —
AVC/AVS
AVC/JAM
AVC/UNI
AVC/SIN
AVC/PIK
AVC/FIR
10/06/77
19
12.9
UNI
10.6
1.2
2.1
1.2
1 .4
1.3
2.1
10/07/77
1
11.6
JAM
6.4
1 .8
1 .8
2.0
1.9
2.4
3.3
10/10/77
7
12.9
JAM
9.1
1 .4
1 .4
1.3
1.9
2.6
10/11/77
9
11.2
PIK
13.3
.8
1.1
1 .4
1.5
.a
3.7
10/12/77
19
13.5
PIK
8.5
1 .6
3.3
_
1.6
10/13/77
19
10.2
PIK
9.9
1 .0
1.1
2.7
1.7
1.0
_
10/14/77
19
12.8
PIK
15.8
.8
1.1
2.0
2.2
.8
10/17/77
36
11.1
UNI
A.9
2.3
-
2.3
_
10/18/77
7
10.2
UNI
7.3
1.4
1.5
1.4
1.8
1.7
_
10/19/77
19
11.5
PIK
11.5
1.0
1.1
2.6
1.9
1.0
_
10/20/77
19
11.3
UNI
8.9
1.3
1.6
1.3
.0
1.3
1.9
10/21/77
10
15.0
PIK
12.0
1 .2
3.1
1.4
1.5
1.2
10/24/77
22
8.9
PIK
8.0
1.1
2.6
1.7
1.4
1.1
3.4
10/25/77
19
8.7
FIR
2.6
3.3
-
_
3.3
10/26/77
19
9.5
PIK
9.4
1.0
-
1.2
1.4
1.0
2.6
10/27/77
5
13.7
SIN
8.6
1.6
-
_
1.6
1.8
10/28/77
1
16.1
PIK
13.6
1.2
-
1.3
1.3
1.2
2.5
10/31/77
22
9.5
PIK
8.3
1.2
-
\ .6
1.4
1.2
3.5
11/01//7
29
8.1
PIK
4.6
1.8
-
2.3
_
1.8
4.6
11/02/77
10
8.1
PIK
7.3
1.1
—
1 .7
1.4
1.1
3.6
1. Where
AVS is the
maximum eight-hour value
(10:00
a.m. to 6:00
p.m.) of
those for the
five permanent
monitors
in the
central buainess
district.
2. Ratio of the maximum study site eight-hour value (10:00 a.m. to 6:00 p.m.) to the maximum of the permanent monitors.
-------
Pedestrian Data
Sampling periods ranged in Length from about two to four hours on two routes
which varied from day to day. For these samples, toncentrations ranged from
1.1 ppm to 11.9 ppm. On some days, the average carbon monoxide for a four-
hour period may exceed 9.0 ppm for a pedestrian. Correlations between con-
centrations on Route A and those on Route B on the same day were better Chan
between morning and afternoon samples from the same route.
29
-------
-------