Chuersuwan, Turpin, and Pietarinen
PAM site operated by NJDEP and Rutgers University and
located ~0.5 mi from the New Brunswick TEOM. Table 1
lists parameters measured at the four sampling locations.
Meteorological parameters include temperature, wind
speed, wind direction, relative humidity (RH), and solar
radiation at ground level. At the New Brunswick PAM
site, temperature, wind speed, and wind direction pro-
files are measured from ground level to 1500 m. Daily
means were calculated from 1-hr average data, monthly
means from 24-hr averages, and annual means from
monthly means.
For the purpose of quality control, filter-based mass
measurements were collected concurrently with New
Brunswick TEOM measurements. A 47-mm Teflon filter
was installed in the 13.7 L/min TEOM bypass flow, and
PM2.5 was collected for 24-hr periods (1200–1200 hr EST)
every third day from February 1998 to February 1999. Fil-
ter samples were collected at the ambient trailer tempera-
ture, approximately 20–25 °C. Filter handling and
weighing protocols followed EPA’s guidance for PM2.5 mass
measurement. Teflon filters were equilibrated at constant
temperature (20–23 °C) and RH (30–40%) for at least 24
hr prior to weighing, and the weighing room tempera-
ture and RH after sample collection were within 2 °C and
5% RH of the precollection values.
period. Detection limits were taken to be 3 times the stan-
dard deviation (σ) of field blank filters.
Sampling Locations
Continuous PM2.5 data were collected in three urban ar-
eas (Newark, Elizabeth, and Camden) and one suburban
area (New Brunswick) of New Jersey. Figure 1 shows the
location of the sampling sites. The station at Newark is
located in an area of dense industrial and commercial
activity at Saint Charles and Berlin Streets near downtown
Newark, which is the largest city in New Jersey with a
population of 270,000. The site is ~0.5 mi west of the
New Jersey Turnpike, a major tollway. The Elizabeth site
is in an industrial area that includes petrochemical plants
and refinery facilities; it is located within 0.3 mi of the
New Jersey Turnpike. Elizabeth has a population of
~110,000.11 The Newark and Elizabeth stations are
~11 and 8.5 mi south and southwest of New York City,
respectively.
The Camden site is located ~2 mi southeast of Phila-
delphia, PA. The area surrounding the sampling site is
mostly residential, with very few commercial activities and
no industrial operations.12 This station is expected to be
influenced by the transport of PM2.5 from greater Phila-
delphia. Camden has a population of ~85,000. New
Brunswick is a small city (population 45,000) in central
New Jersey with few industrial sources and surrounded
by suburban towns. The New Brunswick site is located in
the Rutgers University Gardens. All of these stations are
part of the PM2.5 monitoring network maintained by
NJDEP.
A CAHN C-30 microbalance was used for filter weigh-
ing and was calibrated with a primary mass standard (200
mg) traceable to NIST mass standards at the beginning of
each weighing session. The primary mass standard was
reweighed at the end of each session as a validation check.
Field blanks and laboratory blanks were also weighed for
quality assurance purposes. Mass concentrations of PM2.5
were calculated by subtracting the postcollection weight
from precollection weight and dividing by the volume of
air that was pulled through the filter over the sampling
RESULTS AND DISCUSSION
Filter-Based and Continuous
PM2.5 Measurements
New Brunswick gravimetric measurements and TEOM
measurements collected through the same inlet and inte-
grated over identical 24-hr time periods are shown in Fig-
ure 2. The detection limit for gravimetric measurements
was ~11.4 µg (1.0 µg/m3), expressed as 3 times the stan-
dard deviation of the field blank. The coefficient of deter-
mination (R2) between the gravimetric and TEOM
measurements was 95% (n = 104). The highest correla-
tion (R2 = 98%) was observed during the warmer months
(May–October), as shown in Figure 2b (n = 40). During
the cooler months (November–April), a somewhat lower
correlation (R2 = 87%) was observed. TEOM and gravi-
metric mass concentrations were not significantly differ-
ent, with 95% confidence intervals for either period.
The use of a common sampling inlet and reasonably
low NO3 concentrations are likely explanations for the
good agreement between the 24-hr integrated gravimet-
ric and TEOM mass concentrations. Allen et al.9 also
Table 1. Measurements with 1-hr resolution at each sampling location (July 1997–
June 1998).
Parameters
Measured
Newark
Elizabeth
New Brunswick
Camden
PM2.5
PM10
NOx
VOCs
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
√
O3
√
√
Smoke shade
Temperature
Wind speed
Wind direction
RH
√
√
√
√
√
√
√
√
Solar radiation
1782 Journal of the Air & Waste Management Association
Volume 50 October 2000