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Environmental Quality Branch
PARTICULATES
Air
Quality Report for British Columbia:
Fine Particulate (PM10) Levels (1990-1995)
March 1997
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Table of Contents
Note: At the time of this writing, the current Ministry of Environment was called "BC Environment" / "Ministry of Environment, Lands and Parks."
Executive Summary
Fine
airborne particles called "PM10 " are
considered the most important outdoor air pollutant in British
Columbia today. They are a concern because they can be inhaled
into the lungs, where they can remain for weeks to months
before being removed by the body's natural defense mechanisms.
Medical studies indicate that PM10 is associated
with a variety of health effects, ranging in severity from
increased coughing and school absenteeism, to a significant
rise in the number of premature deaths.
PM10
consists of a mixture of particles of varied size, composition
and origin. These particles originate from both natural
and human-related activities. In addition, they are emitted
directly to the atmosphere (primary particles) and
produced in the atmosphere from chemical and physical processes
involving various gases (secondary particles).
BC Environment (now called the Ministry of Environment, as of June 2005) has monitored PM10 levels at close
to 100 sites in British Columbia since the mid-1980's. The
current network consists of a mix of over 40 manual samplers
and 20 continuous samplers. Manual samplers are typically
operated for a 24-hour period once every six days. Continuous
samplers provide real-time measurements every day of the
year. Most data is forwarded to a central electronic database
for storage.
This
report marks the first overview of PM10 levels
measured in various communities across the province. The
assessment was limited to data collected between 1990-1995,
and primarily to those sites exhibiting good data availability.
Hence, sites with the worst or the best air quality in the
province may not have been considered here. The following
observations were drawn from these analyses:
- Annual
mean concentrations ranged from less than 15 µg/m3
to greater than 50 µg/m3 .
- Concentrations
were highest at sites in the interior of the province
and lowest at sites in southwestern British Columbia.
- Annual
concentrations appear to be decreasing with time at a
number of the sites investigated. However, it is premature
to link these reductions to specific control strategies.
- Exceptions
are found in Prince George and 100 Mile House, where concentrations
have remained the same or appear to be increasing with
time.
- The
provincial air quality objective for PM10 is
50 µg/m3. Few to no exceedances of the
air quality objective were reported for sites in southwestern
British Columbia. At sites in Prince George, Quesnel,
Merritt and Golden, the objective was exceeded, on average,
a minimum of 10% of the time between 1993-1995. This corresponds
to more than 5 weeks per year that the air quality due
to PM10 was considered poor or very poor.
- Large
seasonal variations in PM10 levels were observed.
The highest PM10 concentrations were typically
observed during the winter months, and in particular,
in February and March. Numerous factors may have contributed
to these findings, including seasonal variations in emission
sources and meteorological conditions.
- The
number of 10 µg/m3 increments of PM10
above a threshold level can be used to estimate
the potential for associated health effects due to PM10.
Any non-zero increment indicates an increased risk of
health effects. On an annual basis, the number of PM10
increments calculated for sites in British Columbia
ranged from less than 10 to greater than 1000.
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The
following is a list of groups, whose expertise, knowledge
and helpful comments were invaluable during the preparation
of this document.
Ministry
of Environment, Lands and Parks at the time of this writing
(as of June 2005, Ministry of Environment):
Air
Resources Branch - R. Bennett, B. Beatty, B. Bevan, F.
Geiger, D. Lowe, J. Pretorius, S. Sakiyama, M. Shepherd,
N. Shrimpton, A. Siddiqi, J. Sutherland, R. Marsh, , E.
Tradewell, T. Wakelin
Vancouver
Island Regional Office - W. McCormick
Lower Mainland Regional Office - K. Reid, G. Veale
Southern Interior Regional Office - P. Reid, S. Josefowich
Kootenay Regional Office - B. Kusy
Omineca Peace Regional Office - D. Fudge, S. Lamble
Cariboo Regional Office - E. Plain
Skeena Regional Office - D. Johnson
Greater
Vancouver Regional District - D. Mignacca, A. Percival,
K. Stubbs
Fine
airborne particles called "PM10" have
been identified as the single most important outdoor air
contaminant in British Columbia today (Provincial Health
Officer, 1994). They are a concern because they can be inhaled
into the lungs, where they can remain for weeks to months
before being removed by the body's natural defense mechanisms.
Elevated levels of PM10 are associated with various
health effects, ranging from increased respiratory symptoms
to an increased risk of premature death. Dr. Sverre Vedal,
a medical researcher at the University of British Columbia,
has estimated the health impacts of ambient PM10
levels in this province (Vedal, 1995). They include an extra
82 deaths, 146 extra hospitalizations for lung and heart
disorders and asthma, 283 extra emergency room visits for
asthma, and over 165,000 extra absences from school each
year.
Unlike
other air contaminants such as carbon monoxide or ozone,
which are pure substances, PM10 is a mixture
of particles of varied size, composition and origin. By
definition, PM10 refers to those particles that
are 10 micrometres (µm) or smaller in diameter. A micrometre
(µm) is one-millionth of a metre. Particles of this
size can remain airborne for extended periods of time and
tend to move around just like gases. The very fine particles
can affect visibility as well as human health. They originate
from both natural and human-related activities. Furthermore,
they are emitted directly to the atmosphere (primary
particles) and produced in the atmosphere from chemical
and physical processes involving various gases (secondary
particles).
The
sources of PM10 vary from community-to-community
and from season-to-season. Based on the 1990 provincial
emissions inventory, an estimated 450 thousand tonnes of
PM10 (primary particles) were released into the
atmosphere that year (Stevenson, 1994). As summarized in
Figure 1.1, forest fires and prescribed
burning account for the majority (64%) of these emissions,
and can have a large impact on regional air quality.
Point sources such as pulp mills, sawmills, beehive burners
and grain elevators account for a further 17%, and can affect
local air quality. Smaller contributions from area
sources (e.g. wood stoves, fireplaces and backyard burning);
mobile sources (e.g. diesel trucks); and road dust are also
important to local air quality, as they are numerous and/or
widespread and located in close proximity to where we live.
Secondary
particles were not considered in the emission inventory
estimates, although studies limited to the Lower Fraser
Valley indicate that they comprise up to 50% of the very
fine PM10 particles collected during the summertime
(Lowenthal et al., 1994; Pryor and Steyn, 1994). Sulphur
dioxide (SO2), nitrogen oxides (NOx), various
hydrocarbons and ammonia (NH3) are important
gases involved in the formation of secondary particles.
In the Lower Fraser Valley, major sources of SO2
include the cement and petroleum industries, marine vessels
and motor vehicles (ARB, 1994). Approximately 75% of the
NOx emissions are from motor vehicles and marine vessels.
Motor vehicles, solvent usage and vegetation contribute
over 70% of the hydrocarbon emissions. Agriculture is the
dominant source of NH3.
BC
Environment has implemented a number of programs to reduce
the amount of PM10 emitted into the atmosphere.
Regulations have been passed to reduce smoke from land-clearing
fires and wood stoves. A model bylaw has been developed
to assist local governments in restricting backyard burning.
Beehive burners are being phased out, beginning in the most
smoke-sensitive areas of the province. To reduce emissions
from the motor vehicle sector, the Province has adopted
new gasoline and vehicle emission standards. AirCare, a
vehicle emission maintenance and inspection program in the
Lower Fraser Valley, remains a weapon in the fight against
smog and the associated secondary particulates.
To
characterize PM10 levels in British Columbia,
BC Environment has been monitoring PM10 levels
throughout the province for a number of years. While the
earliest monitoring dates back to 1985, the large-scale
monitoring effort began in 1989. Regional PM10 levels
have been summarized for the Kootenay Region (Mignacca,
1995), the Skeena Region (Johnson, 1997), Prince George
(Lamble and Fudge, 1996), Kelowna and Kamloops (Josefowich
and Reid, 1996), the Cariboo Region (Plain, 1996) and the
GVRD (1995). However, a province-wide review of ambient
PM10 levels has not been carried out to date.
Hence, this report marks the first opportunity to review
ambient PM10 levels at various monitoring sites
throughout the province. This review is limited to data
collected between 1990-1995.
PM10
represents only a fraction of the particulate matter found
in the atmosphere. In order to measure PM10 levels,
it is first necessary to remove that fraction of particulate
matter that is larger than 10 µm. This is done using
a sample inlet which is designed to have a 50% cutpoint
of 10 µm. This means that it collects 50% of all 10
µm particles, and rejects 50%. Hence, particles larger
than 10 µm can be captured, but at progressively lower
efficiencies. This is much like the human respiratory system,
in that a large percentage (but not all) of particles greater
than 10 µm are removed in the oral and nasal passages,
and thereby prevented from reaching the lungs.
Two
different techniques are currently used to measure PM10
in the provincial monitoring network. The manual method
is the traditional method of measuring PM10.
The continuous method, due to its ease of operation and
ability to provide real-time measurements, is finding growing
application throughout the province.
The
manual sampler operates under the following principles.
Air is drawn through a pre-weighed filter for a 24-hour
period at a known flowrate. The filter is then removed and
sent to a laboratory for analysis. The increase in filter
mass, together with the sampling period and sampling flowrate,
are used to calculate the 24-hour PM10 concentration,
typically in units of micrograms per cubic metre (µg/m3).
Additional analyses can be performed on the filter to determine
the chemical composition of the sample. Measurements are
typically made once every six days. This coincides with
the sampling schedule used in the National Air Pollution
Surveillance (NAPS) network. Based on this schedule, a maximum
of about 61 samples can be obtained in any year. This corresponds
to annual coverage of about 17%. Two types of manual samplers
are presently used in the provincial monitoring network:
the size-selective inlet (SSI) high-volume sampler, and
the Partisol sampler. A third type - the dichotomous sampler
- is employed at NAPS sites in Victoria and Vancouver.
The
continuous sampler used in the provincial network is the
Tapered Element Oscillating Microbalance, or TEOM. Its operating
principles are as follows: Heated air is drawn through a
small filter which sits on the end of a hollow, tapered
tube. This tube is fixed at the other end, and therefore
free to oscillate much like a tuning fork. As particles
are collected on the filter, the mass of the filter changes.
This will affect the rate at which the tube oscillates.
The oscillation frequency of the tube is then used to estimate
ambient PM10 levels. The TEOM instrument is expensive
relative to other manual samplers, and there are some concerns
that by heating the sample, some of the particle matter
may volatilize, i.e. vaporize (Meyer et al., 1992).
In addition, the basic setup does not allow for chemical
analyses to be performed on the collected sample, as is
available with the manual samplers. The advantages of the
TEOM are that it can provide continuous measurements of
PM10 levels, 365 days a year, and requires filter
changes only once every two to four weeks.
To
ensure that the PM10 data collected in the province
are scientifically acceptable and consistent throughout
the province, Air Monitoring Guidelines have been prepared
by BC Environment (ARB, 1996). The guidelines describe procedures
for the siting, installation, operation and calibration
of manual samplers. A similar set of guidelines for continuous
samplers is expected in the near future. At present, no
formal province-wide audit program exists for PM10
samplers, although samplers are regularly calibrated, maintained
and operated by regional Ministry staff, contractors and
permittees. It is expected that an audit program will be
initiated in 1997.
Once
a sample has been obtained, all filters from manual samplers
must be sent to a laboratory for further analysis. To ensure
that the proper techniques are used, the laboratory is required
to follow a number of tests according to BC Environment
standards.
Data
from all manual and most continuous samplers are then forwarded
to a central electronic database for storage. The data must
meet a number of screening criteria before being accepted
onto the database. This is done to ensure that only valid
data are archived.
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PM10
has been monitored at close to one hundred different
sites in the province. The current sampling network consists
of a mix of over 40 manual samplers and 20 continuous samplers.
The names and locations of past and present PM10 samplers
in the B.C. network are presented in Appendix I. Samplers
are located in each of the eight regions and sub-regions
of BC Environment, and also in the Greater Vancouver Regional
District (GVRD). Additional monitoring in the province is
conducted by the federal government and industry. Data included
in this report are mostly restricted to that obtained from
BC Environment and GVRD sites.
As
a measure of the air quality in a region, contaminant levels
are compared to air quality objectives. Air quality
objectives are developed by environmental and health authorities
to provide guidance for environmental protection decisions.
They are based on scientific studies which consider the
effects of the contaminant on such receptors as humans,
wildlife, vegetation, and materials, as well as aesthetic
qualities such as visibility.
A national
objective for PM10 is currently being developed.
Recommendations are expected in 1997. Recognizing the threat
that PM10 poses to human health, BC Environment
has established an air quality objective of 50 µg/m3
(24-hour average). The selection of this number was based
on the findings by Vedal (1993) on the effects of woodsmoke
in B.C.. Vedal found that each 50 µg/m3 increment
in PM10 was associated with an increase in health
effects ranging from respiratory symptoms to death. Exceedances
of the air quality objective indicate reduced protection
against associated health effects. Hence, one measure of
PM10 air quality is the number or frequency of
exceedances of the air quality objective.
Air
quality objectives for PM10 and other common
contaminants also form the basis of the Air Quality Index
(AQI). The AQI is a scale used in parts of the province
and elsewhere to determine if air quality is "good",
"fair", "poor" or "very poor".
At sites where numerous contaminants are monitored, the
AQI reflects the concentration of the contaminant that is
highest compared to its respective air quality objective.
Where PM10 is the contaminant of concern, air
quality can be described as shown in Table 5.1. Exceedances
of the air quality objective for PM10 indicate
that air quality may be poor or very poor.
Table
5.1 Description of the air quality index, based on PM10
measurements.
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Air
Quality
Descriptor
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Air
Quality
Index
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PM10
Conc. (24-h)
(µg/m3)
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good
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<
or = 25
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<
or = 25
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fair
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26-50
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26-50
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poor
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51-100
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51-100
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very
poor
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>
100
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>
100
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An
alternate approach to evaluating PM10 air quality
is through the use of PM10 increments. Recent
reviews of the health literature (Dockery and Pope, 1994;
Vedal, 1995) suggest that PM10 causes health
effects at levels as low as 20 µg/m3 (i.e.
below the current provincial air quality objective). Studies
also indicate that each 10 µg/m3 increase
in PM10 above this level (a PM10 increment)
is associated with a linear increase in various health effects,
as summarized in Table 5.2. Hence, the number of increments
provides an estimate of the increased risk that an individual
may experience due to ambient PM10 levels in
their community. Any number of increments above zero indicates
an increased risk. The greater the number of increments,
the greater the risk.
Table
5.2. Health impacts associated with each PM10 increment
(Vedal, 1995).
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Each
PM10 increment is linked with:
-
a 1.0% increase in total number of deaths
-
a 3.4% increase in number of deaths due to respiratory
problems
-
a 1.4% increase in number of deaths due to cardiac
problems
-
a 0.8% increase in hospitalizations due to respiratory
problems
-
a 0.6% increase in hospitalizations due to cardiac
problems
-
a 0.7% increase in hospitalizations due to asthma
-
a 2.3% increase in emergency visits due to chronic
obstructive pulmonary disease
-
a 3.4% increase in emergency visits due to asthma
-
a 4.1% increase in days absent from school
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Before
discussing PM10 levels in B.C., some explanation
of the terminology is warranted. The following explains
terms which are regularly used in this document:
- data
capture - Data capture refers to the percentage of
samples available in any specified period. For instance,
if daily measurements are expected, and only 300 measurements
are available, the data capture is 82%. Data capture is
an important parameter because it reflects how representative
the samples are for the period in question. For example,
an annual average based on only one sample has little
meaning. As noted previously, a limitation with the manual
samplers is that they are typically operated every sixth
day. Hence, they provide coverage for a maximum of 17%
of the year.
- mean
- Also known as the average, it is defined as the sum
of the data, divided by the number of available data.
Over any time period, an actual measurement may fall below
or above the mean concentration.
- maximum
- The maximum refers to the peak concentration. It is
generally representative of extreme rather than typical
conditions. For this reason, it is not a good indicator
of long-term changes in air quality. However, together
with the mean concentration, it does describe the range
of upper values.
- exceedance
frequency - This gives a measure of how often the
air quality objective (50 µg/m3 for PM10)
is exceeded. For instance, if the objective is exceeded
two times out of ten, the exceedance frequency is 20%.
- PM10
increment - In the current context, it is defined
as the number of 10 µg/m3 increments in
ambient PM10 concentrations, beginning at 10
µg/m3 above 20 µg/m3 (i.e.
at 30 µg/m3). The first increment starts
at 30 µg/m3, the second increment at 40
µg/m3, and so on. The number of PM10
increments provides an estimate of the increased
risk that an individual experiences due to ambient PM10
levels. The risk increases linearly with the number
of increments.
In
Section 7, the above parameters will be used to describe
PM10 levels at selected sites in the province.
The
following is an overview of PM10 levels between
1990-1995 at selected stations within each of the eight
regions and sub-regions of BC Environment and the GVRD.
Site selection was based on data availability and, where
more than one monitor was located in a community, on how
well the site represented conditions throughout the community.
Dichotomous sampler sites in the NAPS network were not included
in this analysis.
All
available data between 1990-1995 were used. In the case
of some of the manual samplers, sampling was conducted at
intervals other than the NAPS schedule (i.e. once every
six days) to investigate special events such as forest fires,
when PM10 levels are expected to be very high.
In such cases, the annual statistics may be biased on the
high side.
For
each of the selected sites, a page of summary graphs is
provided. Unless specified otherwise, all available data
are plotted against time. Mean and maximum PM10
concentrations, on both an annual and monthly basis, are
presented. To evaluate current and historical PM10
levels, annual exceedance frequencies and the number of
annually adjusted PM10 increments are also provided.
This data is further summarized in tabular form in Appendix
II.
Where
data capture is less than 75%, the year in question is identified
by an asterisk in the figures, and by italicized text in
Appendix II. Care should be exercised in drawing conclusions
based on partial datasets.
Although
each monitoring station meets a set of minimum siting criteria
set out by BC Environment, local differences exist for a
number of factors which will affect measurements: proximity
to sources of PM10, local landuse types, topography
and meteorological conditions. Hence, care should also be
exercised in extending information from one point to an
entire community, and in comparing measurements from one
community to another.
Based
on the available data from the selected stations, annual
mean PM10 concentrations varied from 11 to 54
µg/m3. Some sites recorded no exceedances
of the air quality objective for PM10, while
one site recorded a maximum exceedance frequency of over
38%. The number of annually adjusted PM10 increments
ranged from less than 10 to greater than 1000. Any increments
greater than zero suggest an increased risk of health-related
effects.
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PM10
monitoring in the Vancouver Island Region has been carried
out in Victoria, Port Alberni, Crofton, Harmac, Elk Falls
and Gold River. The current network includes sites in Victoria,
Port Alberni and Elk Falls. The following analyses focus
on data collected at the Victoria and Port Alberni (Courthouse)
monitoring sites.
While
limited PM10 monitoring in Victoria was carried
out as early as 1988, regular monitoring did not begin until
October 1992. Data from 1992 onwards are summarized on an
annual and monthly basis in Figure
7.1 and in Appendix II. Data capture at this site has
been satisfactory over the past three years. Relative to
most other areas of the province, PM10 levels
have been low. Between 1993-1995, no exceedances of the
air quality objective were recorded. Mean PM10
concentrations decreased from 20 to 14 µg/m3
during this period. The number of PM10 increments
decreased from 66 in 1993 to 7 and 13 increments in 1994
and 1995, respectively. However, while these numbers are
low, they still represent an increased risk of health effects
due to PM10.
On
a monthly basis, the highest mean concentrations were found
in February (22 µg/m3) and October (20 µg/m3)
and the lowest levels in April-August (12-14 µg/m3).
The highest concentration measured at this site was 47 µg/m3
in October 1993.
The
Courthouse site is one of the oldest monitoring sites for
fine particulates in the provincial network, with measurements
dating back to February 1985. Reflecting the previous definition
for "inhalable particulates," the early measurements
are believed to be for PM15, i.e. particles 15
µm and smaller in diameter. The current analysis is
restricted to data from 1990 onwards, which are known to
represent PM10. Data are summarized on an annual
and a monthly basis in Figure 7.2
and in Appendix II.
Data
capture has been satisfactory since 1993. PM10 levels
at this site have been very low relative to other areas
of the province, particularly over the past two years. In
1994 and 1995, no exceedances of the air quality objective
for PM10 were reported. Mean concentrations ranged
from 11-13 µg/m3. The number of annual PM10
increments was less than 10, which is a significant
decrease from the over 200 increments estimated for 1993.
On
a monthly basis, mean PM10 concentrations were
highest in December-February (24-25 µg/m3)
and lowest during April-August (12-15 µg/m3).
The maximum recorded concentration was 81 µg/m3
in June 1992. Exceedances of the air quality objective were
observed during the months of January-February, June and
October.
PM10
has been monitored at several locations within the
Lower Mainland Region. The current provincial network consists
of four manual samplers at Pitt Meadows, Albion, Mission
and Hope, and three continuous monitors at Squamish, Abbotsford
and Chilliwack. Additional monitoring is done by permittees
in Langdale, Gibsons and Powell River. Data from sites in
Pitt Meadows, Abbotsford and Hope are discussed in the following.
A manual
sampler began operating at the Pitt Meadows Airport in February
1991. Data from this site are summarized on an annual and
monthly basis in Figure 7.3 and
in Appendix II.
Data
capture has been satisfactory, with the exception of 1992
when it was marginal. PM10 levels have been very
low at this site, with no exceedances of the air quality
objective observed to date. PM10 air quality
has been particularly good over the past two years, reflected
by annual concentrations of only 13 µg/m3
and PM10 increments of no greater than 20. However,
it is unclear whether these apparent improvements are due
to reduced emissions or other factors.
On
a monthly basis, the highest mean PM10 concentrations
were found in September-October and January (19-21 µg/m3)
and the lowest levels in November-December (12 µg/m3
). The highest concentration observed at this site was 47
µg/m3 in January and October 1993.
A manual
sampler was installed on top of the Abbotsford Library in
May 1992, and was shut down in March 1995. Current PM10
measurements are from a continuous sampler which was
installed in July 1994. Data from this site are summarized
on an annual and a monthly basis in Figure
7.4 and in Appendix II. Data shown prior to 1995 are
from the manual sampler, while more recent data are from
the continuous sampler.
Data
capture at this site has been satisfactory over its three
full years of operation (1993-1995). During this period,
mean concentrations decreased from 23 to 18 µg/m3,
while exceedance frequencies fell from about 4% to 1%. The
number of PM10 increments, which reflect an increased
risk of health effects due to PM10, fell from
124 in 1993 to less than 70 in 1994 and 1995. Although PM10
levels at this site are low relative to many other
areas in the province, they are high relative to other parts
of the Lower Mainland Region. On a monthly basis, the highest
mean concentrations were found in September (29 µg/m3)
and January (24 µg/m3) and the lowest levels
in October-December (14-16 µg/m3). The highest
observed concentration was 60 µg/m3 in June
1995. Exceedances were limited to the months of February,
May-June and September.
A manual
sampler was installed at the Hope Firehall in March 1991.
Data from this site are summarized on an annual and monthly
basis in Figure 7.5 and in Appendix
II. Data capture over the past five years has been acceptable.
With the exception of 1992, no exceedances of the air quality
objective have been measured at this site. PM10
levels have fluctuated from year-to-year, with the lowest
mean concentrations occurring in 1994 and 1995 (13-14 µg/m3
). The number of PM10 increments, which reflect
an increased risk of health effects due to PM10,
ranged from 5-34 over the past two years.
On
a monthly basis, the highest mean PM10 concentrations
were found in the months of March (25 µg/m3
) and September (20 µg/m3), and the lowest
levels in December (9 µg/m3). The highest
concentration recorded at this site was 107 µg/m3
in March 1992, the only month during which an exceedance
of the air quality objective was observed.
The
current GVRD PM10 monitoring network includes
two manual samplers and eight continuous samplers spread
among eight different sites throughout the region. The first
manual samplers began operating in October 1989, while the
first continuous samplers date back to October 1993. Data
from the following sites will be discussed: Kitsilano (Vancouver);
Rocky Point Park (Pt. Moody); and Surrey.
The
Kitsilano site is located in a suburban setting on the west
side of Vancouver, at the Kitsilano Senior Secondary School.
A manual sampler began operating at this site in July 1991.
A continuous sampler was added in December 1993. Data are
summarized on an annual and monthly basis in Figure
7.6 and in Appendix II. Data prior to 1994 are from
the manual sampler. Data from 1994 onwards are from the
continuous sampler.
Data
capture at the Kitsilano site has been satisfactory over
its four full years of operation (1992-1995). Relative to
other areas of the province, PM10 levels at this
site have been very low, and appear to have decreased over
the past few years. Mean concentrations were 18-21 µg/m3
in 1992-1993, and only 15 µg/m3 in 1994-1995.
The number of PM10 increments, reflecting an
increased risk of health effects due to PM10,
dropped from greater than 45 to less than 15 over the same
interval.
On
a monthly basis, the highest mean PM10 concentrations
were observed in January (21µg/m3 ), and
the lowest levels in March-August (14-15 µg/m3
). The only exceedances ever observed at this site occurred
in January 1993. The maximum concentration was 58 µg/m3.
A manual
sampler was installed in Rocky Point Park, Port Moody in
March 1990, and a continuous sampler was added in November
1993. Data are summarized on an annual and monthly basis
in Figure 7.7 and in Appendix
II. Data prior to 1994 are from the manual sampler, and
data from 1994 onwards are from the continuous sampler.
Data
capture at this site has been satisfactory. PM10
concentrations have been low relative to many other areas
of the province, particularly over the past two years. In
both 1994 and 1995, the mean concentration was 17 µg/m3
and the maximum concentration was 39-40 µg/m3.
No exceedances of the air quality objective were recorded.
The number of annual PM10 increments, representative
of increased health risks due to PM10, was less
than 25 both years.
On
a monthly basis, the highest mean concentrations were observed
in January and September (22-23 µg/m3 ),
and the lowest concentrations in December (13 µg/m3).
The highest measurement at this site was 53 µg/m3
in April 1991. Exceedances of the air quality objective
were limited to the month of April.
A continuous
sampler began operating at the Surrey East site in January
1994. Data are summarized on an annual and a monthly basis
in Figure 7.8 and in Appendix
II. Data capture at this site has been satisfactory. Observed
PM10 levels have been very
low,
with no exceedances reported and few annual PM10
increments estimated. Little difference was noted between
1994 and 1995 levels. Mean and maximum concentrations were
14 and 34 µg/m3, respectively, for both
years. On a monthly basis, the highest mean PM10
concentrations were observed in January (17 µg/m3
) and September (18 µg/m3) and the lowest
levels in December (10 µg/m3).
The
Southern Interior Region (excluding the Okanagan sub-region)
is serviced by manual PM10 samplers in Kamloops
and Merritt. An additional continuous sampler is located
in Kamloops. PM10 levels in both communities
are discussed.
PM10
monitoring in Kamloops and its environs began in January/February
1990 at a total of four sites: the Airport, BCTel Valleyview,
the Federal Building, and Brocklehurst. A fifth sampler
at Westsyde began operating in May 1990. A continuous sampler
was added to the Brocklehurst site in January 1994. At present,
only the manual sampler at the Federal Building and the
continuous sampler at Brocklehurst are still operating.
Data from the Brocklehurst site are summarized on an annual
and monthly basis in Figure 7.9
and in Appendix II. Unless indicated otherwise, data prior
to 1995 are from the manual sampler, and recent data are
from the continuous sampler.
Data
capture at the Brocklehurst site has been satisfactory.
Mean PM10 concentrations have fluctuated from
year-to-year. However, it is noted that mean concentrations
from 1994-1995 (17-19 µg/m3) are substantially
lower than 1990-1991 levels (26-29 µg/m3). During this
period, exceedance frequencies dropped from 8-11% to approximately
2%. The number of PM10 increments, an indicator
of increased risk of health effects due to PM10,
decreased from greater than 300 to less than 75.
On
a monthly basis, the highest mean PM10 concentrations
were observed in February-March (26-31 µg/m3)
and the lowest levels in April-August (15-18 µg/m3).
The highest concentration observed at this site was 221
µg/m3 in February 1990. (1) Exceedances
of the air quality objective have occurred during October-December,
February-May and July.
(1)
A dust storm associated with extremely high PM10
concentrations was not captured in this analysis. On March
4, 1995, hourly concentrations exceeded 900 µg/m3
and the daily mean exceeded 350 µg/m3.
The
manual sampler in Merritt began operating in January 1990.
Data are summarized on an annual and monthly basis in Figure
7.10 and in Appendix II.
Data
capture at this site has ranged from marginal to satisfactory.
Based on the available data, PM10 levels in Merritt
rank among the worst in the province. Mean concentrations
in excess of 40 µg/m3, exceedance frequencies
in excess of 20%, and annual PM10 increments
in excess of 500 have been calculated for at least three
of the past six years . However, air quality in recent years
is much improved over earlier levels. For instance, mean
concentrations have decreased from 42-43 µg/m3
in 1990-1991 to 32-36 µg/m3 in 1994-1995.
The number of annual PM10 increments have similarly
dropped, from near 750 to less than 600. Nevertheless, the
more recent PM10 measurements are still high
relative to many other areas of the province, as reflected
by an exceedance frequency of 20% in 1995.
In
terms of monthly variations, mean PM10 levels
were highest in February-March (48-62 µg/m3)
and in June-August (39-41 µg/m3). The latter
observation is unusual, as most other sites in the province
experience lower PM10 levels during the summer.
Instead, the lowest mean monthly concentrations were observed
in September-November and January (29-33 µg/m3
). The highest PM10 concentration recorded at
this site was 167 µg/m3 in December 1994.
Exceedances of the air quality objective were observed in
each month of the year.
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PM10
monitoring in the Kootenay Region dates back to April 1985,
at the Cranbrook Amy Woodland site. Since this time, PM10
has been monitored at approximately 20 different sites.
The current active network includes three continuous monitors
(Trail, Creston and Cranbrook) and eleven manual samplers
(Trail, Castlegar, Nelson, Nakusp, Slocan, Revelstoke, Golden,
Skookumchuk, Invermere, Cranbrook and Creston). Data from
the monitoring sites in Trail, Creston, Cranbrook and Golden
are discussed below.
The
Trail PM10 monitoring site is located in Butler
Park, which lies 1.5 km to the east of the Cominco lead
smelter. The manual sampler has been in operation since
April 1990. A continuous sampler was installed at the same
site in April 1994. Annual and monthly PM10 statistics
are summarized in Figure 7.11
and in Appendix II. In the current treatment, data prior
to 1995 are from the manual sampler, and recent data are
from the continuous sampler.
Over
the past five years of operation, data capture has been
satisfactory at this site. The lone exception was 1993,
when data capture was marginal. Annual mean PM10
concentrations have varied from 21-27 µg/m3,
with the lowest concentrations and the lowest number of
PM10 increments (79) of the five-year period
occurring in 1995. During that year, the air quality objective
for PM10 was exceeded less than 1% of the time.
On
a monthly basis, the highest mean PM10 concentrations
were found in February (27 µg/m3) and September
(26 µg/m3), and the lowest levels in December
(18 µg/m3). The highest PM10
concentration recorded at this site was 73 µg/m3
in February 1991. Exceedances of the air quality objective
were limited to the months of February, July-August, and
October-November.
The
manual sampler in Creston is located on the roof of the
Creston Hospital. PM10 sampling began here in
September 1990. A continuous sampler was installed at a
second site in Creston in October 1994. The current treatment
is restricted to data from the hospital site. Annual and
monthly statistics are summarized in Figure
7.12 and in Appendix II.
In
1992, Creston experienced some of the highest PM10
levels in the entire province. The annual mean PM10
concentration was 54 µg/m3 and the reported
maximum concentration was 151 µg/m3. The
air quality objective was exceeded 38% of the time, and
over 1000 PM10 increments were estimated. Since
1992, PM10 levels have been considerably improved.
Mean concentrations have ranged from 20-25 µg/m3,
and exceedance frequencies have varied from 2-6%. The number
of annual PM10 increments, which reflect an increased
risk of health effects due to PM10, are still
high. However, they have not exceeded 200 since 1992. While
not indicative of long-term trends, PM10 levels
in 1995 were lower than any previous year.
In
terms of monthly variations, the highest mean PM10
concentrations were found in January-February (45-49 µg/m3)
and October (41 µg/m3), and the lowest levels
were found in December (20 µg/m3). The only
months in which exceedances of the air quality objective
were not observed were August and December. The highest
concentration ever reported for this site and in the province,
419 µg/m3, was in October, 1991.
Cranbrook
is currently serviced by a manual sampler at the Cranbrook
Swimming Pool and a continuous monitor located on 14th Avenue
(PR3). Monitoring at the swimming pool began in March 1990,
and the data are summarized on an annual and monthly basis
in Figure 7.13, and in Appendix
II.
Data
capture at this site has been satisfactory for all but one
of the past six years. PM10 levels have been
high relative to most other areas of the province. Between
1990-1994, mean PM10 levels varied from 28-31
µg/m3. The air quality objective was exceeded
more than 10% of the time. The number of PM10
increments, reflecting an increased risk of health effects
due to PM10, averaged over 285. In 1995, however,
exceedance frequencies dropped to about 6%. The mean concentration
fell to 21 µg/m3 and the number of PM10
increments declined by over 50%. It is unclear what particular
factors led to this apparent improvement in air quality.
On
a monthly basis, the highest mean PM10 concentrations
were found in March (47 µg/m3) and the lowest
values in June (18 µg/m3). Exceedances of
the air quality objective were observed in every month of
the year except June. The highest PM10 concentration
observed at this site was 150 µg/m3 in January
1992.
The
manual sampler in Golden began operating in January 1992.
Data are summarized on an annual and monthly basis in Figure
7.14 and in Appendix II.
Data
capture at this site has been satisfactory over the past
three years of full operation. During this period, mean
PM10 concentrations decreased from 40 to 32 µg/m3.
Exceedance frequencies also fell from 32% to 13%. The number
of annual PM10 increments, which reflect increased
risks of health effects due to PM10, dropped
from 647 to 372. While these numbers suggest improving air
quality in Golden, these levels are still very high relative
to other areas of the province.
In
terms of monthly variations, the highest mean PM10
concentrations were found in January-March (52-64 µg/m3),
and the lowest levels in June-August (18-20 µg/m3).
The air quality objective was exceeded in every month of
the year except June and August. The highest recorded concentration
(160 µg/m3) occurred in March 1994.
PM10
monitoring in the Cariboo Region began in May 1987. Measurements
have been made at approximately 15 different locations.
In the current provincial network, there are three active
manual samplers in Williams Lake and one in 100 Mile House.
A manual sampler in Quesnel was deactivated in early 1995.
The network also includes four active continuous instruments
in Williams Lake and Quesnel. In the following, data from
manual samplers in Quesnel, Williams Lake (Firehall) and
100 Mile House are presented.
PM10
monitoring at the Quesnel Firehall began in November 1990,
and continued until February 1995. Data from this site are
summarized on an annual and monthly basis in Figure
7.15 and in Appendix II.
Data
capture was satisfactory over the four full years of operation
(1991-1994). PM10 levels at this site are high
relative to other sites in the province. In 1994, the best
year in terms of PM10 air quality, the mean concentration
was 31 µg/m3 and the air quality objective
was exceeded 13% of the time. Over 400 PM10 increments,
indicative of an increased risk in health effects due to
PM10, were estimated for the year. However, this
is seen as an improvement over previous years when the number
of PM10 increments exceeded 500 and exceedance
frequencies approached 20%. PM10 levels in 1992
were particularly bad, with exceedance frequencies of 27%
and the number of increments exceeding 1000.
On
a monthly basis, mean PM10 concentrations were
highest during March (116 µg/m3 ), and lowest
during December (20 µg/m3 ). Exceedances
were observed during all months of the year. Very high concentrations
have been experienced at this site, as evidenced by maximum
levels of 391 µg/m3 in March 1992 and 212
µg/m3 in March 1994.
PM10
monitoring in Williams Lake began in May 1987, at the Williams
Lake Firehall. This site is located in a residential/business
area of the city. Data from this site are summarized on
an annual and a monthly basis in Figure
7.16 and in Appendix II.
Data
capture has been satisfactory over the past five years of
operation, with the exception of 1992, when it was marginal.
Prior to 1994, PM10 levels measured at the Williams
Lake site were among the highest in the province. Substantial
improvement has been noted over the past two years. Between
1993 and 1995, annual mean concentrations decreased from
32 µg/m3 to 22 µg/m3. Exceedance
frequencies similarly decreased, from 16% to 2%. The number
of PM10 increments, which are indicative of an
increased risk of health effects due to PM10,
decreased by over 50% to 153.
In
terms of monthly variations, the highest mean concentrations
were found in February-March (36-46 µg/m3)
and September-October (34-35 µg/m3), and
the lowest levels in December-January (15-18 µg/m3).
The highest concentration recorded at this site was 125
µg/m3 in February 1991. The only months
during which exceedances of the air quality objective were
not recorded were January and June.
PM10
monitoring in 100 Mile House began in March 1993. The data
are summarized on an annual and a monthly basis in Figure
7.17 and in Appendix II.
Data
capture at this site has been satisfactory. Unlike other
areas of the Cariboo Region, mean PM10 levels
have actually increased over the last three years, from
18 µg/m3 in 1993 to 27 µg/m3
in 1995. Similarly, exceedance frequencies have increased
from 4 to 13% . The number of PM10 increments,
which reflect an increased risk of health effects due to
PM10, more than tripled from 91 to 282.
On
a monthly basis, mean concentrations were highest in March
(43 µg/m3) and lowest in November-January
(8-11 µg/m3). The highest PM10
concentration recorded at this site was 105 µg/m3
in March 1994. Exceedances of the air quality objective
were observed during the months of February-March, May,
July and September.
PM10
has been sampled at numerous locations in the Skeena Region.
The current monitoring network includes manual samplers
in Terrace, New Hazelton, Burns Lake and Kitimat, and continuous
samplers in Houston, Smithers and Terrace. The continuous
samplers provide the most current and complete data record;
however, archiving difficulties limit the current analysis
to the data from the manual samplers. Data from the manual
sampling sites in Terrace and New Hazelton are presented
in the following.
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The
manual sampler in Terrace is located at the firehall. It
began operation in October 1993. Annual and monthly PM10
statistics from this site are summarized in Figure
7.18 and in Appendix II.
Data
capture during the two complete years of operation is satisfactory.
During this period, mean concentrations ranged from 21-23
µg/m3. The air quality objective for PM10
was exceeded 3-6% of the time. The number of annual PM10
increments, indicative of an increased risk of health effects
due to PM10, varied from 152-175 during this
time period. The highest PM10 concentration observed
at this site was 93 µg/m3 in September 1995.
On average, PM10 levels were highest during the
month of March (33 µg/m3) and lowest between
November -January (12-15 µg/m3). Exceedances
of the air quality objective were found in the months of
March, July and September.
The
manual sampler in New Hazelton began operating in March
1993. Annual and monthly statistics are summarized in Figure
7.19 and in Appendix II.
Data
capture was acceptable in 1994 and marginal in 1995. During
this time, mean PM10 concentrations ranged from
25-26 µg/m3. The air quality objective for
PM10
was
exceeded 8-12% of the time. Over 200 PM10 increments,
which are indicative of an increased risk of health effects
due to PM10, were estimated. Based on the limited
dataset, mean PM10 concentrations were highest
during the months of May and December, and lowest in February.
Exceedances of the air quality objective were observed during
the months of May-June, September, and November-December.
The
City of Prince George is home to a number of large industrial
facilities, including 3 pulp and paper mills, a refinery,
as well as numerous sawmills and related activities. Reflecting
the heavy concentration of industry within Prince George,
PM10 has been measured at a total of seven different
locations within the city since August 1990. The current
monitoring network includes six manual samplers and two
continuous instruments. Data from the Gladstone, Plaza 400
and BCRail sites are presented in the following. Limited
monitoring has also been carried out in Chetwynd and Ft.
St. James, but the data are not included in this report.
Gladstone
School is located in a residential area of Prince George.
A manual sampler has been operating at this site since June
1992. A continuous sampler was added in December 1995. Data
from the manual sampler are summarized on an annual and
a monthly basis in Figure 7.20 and
in Appendix II.
Data
capture has been satisfactory for the three full years the
sampler has been in operation. PM10 levels have
changed little over the past two years at this site. Mean
annual concentrations were 17 µg/m3 both
years. The number of PM10 increments, which reflect
an increased risk of health effects due to PM10,
were 79-85. Exceedance frequencies were slightly higher
in 1995 (3%) than in 1994, when no exceedances were reported.
However, this is seen as an improvement over 1993 levels,
when the air quality objective for PM10 was exceeded
approximately 9% of the time, and a total of 282 PM10
increments were calculated.
On
a monthly basis, the highest mean PM10 concentrations
were found in January-February (28-29 µg/m3)
and the lowest levels in June-July and November (13-15 µg/m3
). The highest concentration measured at this site (122
µg/m3) was observed in February 1993. Exceedances
of the air quality objective were found in the months of
December-March, and in August.
Plaza
400 is located in downtown Prince George. A manual sampler
began operating at this site in August 1990. A continuous
sampler was added in March 1992. Data from the manual sampler
are summarized on an annual and a monthly basis in Figure
7.21 and in Appendix II.
Similar
to the Gladstone site, PM10 levels measured at
Plaza 400 have remained fairly stable over the past few
years. However, concentrations are substantially higher
at the Plaza 400 site, with mean concentrations ranging
from 24 to 30 µg/m3 between 1991-1995. (2)
During this period, the air quality objective was exceeded
10-17% of the time. The number of PM10 increments,
which reflect an increased risk of health effects due to
PM10, varied from 225 to 384.
On
a monthly basis, mean PM10 concentrations were
highest in February-March (34-51 µg/m3)
and lowest in July (21 µg/m3). The highest
concentration observed at this site was 217 µg/m3
in March 1991. May and July were the only months in which
no exceedances of the air quality objective were observed.
(2)
Data from the continuous sampler indicate slightly lower
levels, with mean concentrations of 22-24 µg/m3,
exceedance frequencies of 5-9% and increments of about 170-230
between 1994-95
The
BC Rail site is representative of an industrial setting.
It was originally located to monitor emissions from nearby
sawmill burners. A manual sampler has been operating at
this site since May 1990, but archived data are available
from July 1992. Annual and monthly statistics are summarized
in Figure 7.22 and in Appendix
II.
PM10
levels at the BC Rail site are among the highest in Prince
George and in the province, with no indication of a downward
trend with time. In 1995, the air quality objective for
PM10 was exceeded almost one-third of the time,
more frequently than any previous year. The mean concentration
was 41µg/m3 . A total of 723 annual PM10
increments, reflecting an increased risk of health effects
due to PM10, were calculated.
On
a monthly basis, mean PM10 concentrations were
highest during February-April (45-63 µg/m3)
and August-September (47-49 µg/m3) and lowest
during November-December (26 µg/m3 ). Exceedances
were observed in every month of the year. The highest concentration
recorded at this site was 181 µg/m3 in March
1995.
PM10
monitoring in the Okanagan began in May 1990. Five manual
samplers are deployed in Vernon, Penticton, Lumby, Grand
Forks and Kelowna. A continuous monitor is also located
in Kelowna. Data from the Vernon and Kelowna sites are discussed
below.
A manual
sampler has been operating intermittently in downtown Vernon
since October 1989, and more regularly since 1992. Data
from this site are summarized on an annual and a monthly
basis in Figure 7.23 and in Appendix
II.
Data
capture at this site has not been very good, particularly
in the years prior to 1995, and so caution must be exercised
in evaluating these numbers. The available data indicate
that PM10 levels have shown a marked improvement
over the past four years. In 1992, the air quality in Vernon
due to PM10 was among the worst in the province.
Mean PM10 levels were 42 µg/m3,
and the air quality objective was exceeded about 32% of
the time. The number of PM10 increments, reflecting
an increased risk in health effects due to PM10,
totalled over 700 for the entire year. By 1995, however,
mean PM10 levels had fallen to 22 µg/m3
and the air quality objective was exceeded only 2% of the
time. The number of PM10 increments had decreased
to 119.
On
a monthly basis, the highest mean concentrations were found
to occur in February-March (46-65 µg/m3)
and October (40 µg/m3). The lowest concentrations
were found in July (20 µg/m3), the only
month during which exceedances of the air quality objective
were not observed. The highest concentration measured at
this site between 1990-1995 was 135 µg/m3
in October 1992.
Both
a manual and a continuous sampler are located at the KLO
Road campus of Okanagan University College in Kelowna. The
manual sampler began operating in September 1989, and the
continuous sampler in January 1994. Data from the manual
sampler are summarized on an annual and monthly basis in
Figure 7.24 and in Appendix II.
Data
capture has been satisfactory for all years except 1992.
Relative to other locations in the Okanagan such as Vernon,
PM10 levels at the Kelowna site have been fairly
low. Although not necessarily indicative of long-term trends,
the lowest mean concentrations have been observed over the
past two years. In 1994 and 1995, mean concentrations were
21 and 19 µg/m3, respectively.(3) The air
quality objective was exceeded about 2% of the time. The
number of PM10 increments, which are indicative
of an increased risk in health effects due to PM10
levels, were 133 and 79, respectively.
On
a monthly basis, the highest mean concentrations were found
in February-March (36-39 µg/m3) and the
lowest concentrations in June (12 µg/m3).
The highest daily concentration measured at this site was
130 µg/m3 in October 1991. Exceedances of
the air quality objective were observed during the months
of December-March, May, July and October.
(3)
Measurements from the continuous monitor indicate slightly
lower PM10 levels. In 1995, the mean concentration
was 17 µg/m3, the exceedance frequency was
less than 2% and approximately 60 increments were calculated.
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Fine
particulate matter, PM10, has been measured at
close to 100 sites throughout the province over the past
10 years. Although parts of the data have been reviewed
on a regional basis, this report marks the first opportunity
to evaluate province-wide levels.
The
current assessment was lim | |
