TSD- 3a 

Analysis of Ambient PM2.5 Mass and Speciation 

for the New York Metropolitan Area through 2006 

Bureau of Air Quality Analysis and Research 

Division of Air Resources 

New York State Department of Environmental Conservation 

Albany, NY 12233 

December 14, 2007 
Introduction

 With the promulgation of the annual and daily PM2.5 national ambient air quality 

standards (NAAQS) in 1997, the New York State Department of Environmental 

Conservation (NYSDEC) initiated monitoring this pollutant on a statewide basis 

beginning in 1998/1999. A majority of the monitoring efforts to date have involved 24-

hour, filter-based Federal Reference Method (FRM) samplers. Most of the FRM 

samplers operate on a 1-in-3-day schedule, although a few monitors operate on a daily 

basis. Also, as per network design requirements, several FRM sites have collocated 

duplicate samplers. 

 The PM2.5 NAAQS is mass-based, but ambient PM2.5 has a complex morphology 

and chemical composition. In order to obtain information on species composition, the 

NYSDEC also has operated Speciation Trends Network (STN) monitors at several 

locations across the state. Similar to the FRM network, the STN samplers operate on a 1-

in-3-day schedule. The STN program provides for the concentration of major ions, 

carbon compounds, and trace elements, which generally constitute the bulk of PM2.5

mass. 

Although time series of ambient PM2.5 mass and species are relatively short 

compared to other criteria pollutants, such as ozone, it is nonetheless important to 

examine temporal and seasonal trends in the data, in addition to characterize current 

ambient levels. Here we present such trends on a composite basis over the New York 

portion of the New York City PM2.5 non-attainment area (NYC NAA), corresponding to 

Bronx, Kings, Nassau, New York, Orange, Queens, Richmond, Suffolk and Westchester 

Counties. All data used in this analysis are publicly available on the NYSDEC Division 

of Air Resources’ ambient PM2.5 monitoring website (please see 

http://www.dec.ny.gov/chemical/8539.html). 

FRM data

Table 1 lists the site locations and sampling periods between 1999-2006 for all 

FRM monitors in the three NYSDEC sub-regions that cover parts of the NYC NAA: 

Region 1 (Long Island; 6 sites), Region 2 (New York City; 19 sites), and Region 3 

(Lower Hudson River Valley; 3 sites). The analysis included Dutchess County for 

completeness, even though it is not part of the NYC NAA area. Seven of the Region 2 

sites have collocated duplicate monitors. Three of the sites also operated daily for at least 

part of the time. A map of the FRM locations is shown in Figure 1. 

Figure 2 displays the composite average FRM mass by NYSDEC region, using all 

valid data from 1999-2006. The averages presented in Figure 2 do not represent design 

values for attainment/regulatory purposes; however, the annual NAAQS of 15 μg m-3 is 

shown for reference. This figure illustrates that on average, PM2.5 is higher in Region 2 

than the surrounding areas. Whereas the average levels in New York City range from 

about 13-15 μg m-3, the average levels in the surrounding counties is about 10-12 μg m-3. 
One other feature evident in Figure 2 is that PM2.5 levels in the most recent few years are 

generally lower than levels measured in 1999-2001. 

Figure 3 displays the composite seasonal/quarterly variations in FRM mass by 

NYSDEC region, again using all valid data from 1999-2006. In Regions 1 and 3 there 

appears to be a warm season maximum; this corresponds to the time of maximum 

photochemical activity and secondary particulate formation. In Region 2 the PM2.5 levels 

are high in during both the warm and cold seasons. The high levels during the colder 

months are likely indicative of local sources in the New York City, such as space heating, 

as well as the effects of large urban emissions being mixed through a shallow 

atmospheric boundary layer. 

Tables 2 and 3 display the annual average and 98th percentiles of FRM mass, 

respectively, from 2000-2006. Only those years with at least 75% valid samples are 

included in these tables. Note that some of the values presented in Tables 2 and 3 

correspond to years that do not necessarily have four complete quarters. Similar to 

Figure 2, Table 2 indicates than on an average basis PM2.5 levels are generally lower in 

the most recent years compared to earlier years. In particular, average PM2.5 levels in 

2006 were generally the lowest in this seven-year period. The 98th percentiles presented 

in Table 3 are related to the daily PM2.5 NAAQS, which consists of the average of the 

98th percentile values over three consecutive years. Currently the daily NAAQS is 65 μg 

m-3, and Table 3 shows that all sites in the New York metropolitan area have been well 

below this level. 

Table 4 lists the linear trends in PM2.5 mass at longest-running sites FRM sites in 

the New York metropolitan area. These sites operated from 1999/2000 through 2006, 

and the trends reported in Table 4 are based on quarterly average values at each site. 

Only those quarters with at least 10 valid data points were included in the linear trend 

estimates. Consistent with the composite averages presented earlier, PM2.5 mass appears 

to be decreasing at each of these longest-running sites, by ~0.1-0.5 μg m-3 yr

-1. 

STN data

Table 5 lists the site locations and sampling periods of the STN monitors. Each of 

these sites is collocated with an FRM monitor. The STN samplers collect five ions – 

sulfate (SO4), nitrate (NO3), ammonium (NH4), potassium (K), and sodium (Na) – nearly 

50 trace elements, and various carbon species – elemental carbon (EC) and organic 

carbon (OC). For this analysis, we assume that PM2.5 is primarily composed of only SO4, 

NO3, NH4, EC, OC, and major crustal species (major oxides of Al, Ca, Fe, Si, and Ti; e.g. 

US EPA, 2007), and hereafter refer to the sum of these species as the “reconstructed 

mass.” Although the PM2.5 NAAQS is strictly mass-based, here we attempt to 

approximate the average species composition of the ambient PM2.5 in NYC. 

We adjusted the OC value by subtracting a constant, monitor-specific blank, and 

applying a multiplicative factor of 1.8 to account for the non-carbon composition (O, H, 

etc.). In various EPA documents, a blank of 1.40 μg m-3 for MetOne SASS instruments 
(Canal Street Post Office, N.Y. Botanical Gardens) and 0.93 μg m-3 for R&P 2300 

ACCU instruments (I.S. 52, Queens College II/P.S. 219) is assumed (e.g., 

http://www.epa.gov/airtrends/aqtrnd03/pdfs/2_chemspecofpm25.pdf). We then 

calculated the composite average of each of these components across all four STN sites 

for all valid data points, as well as for just the winter (December-February) and summer 

(June-August) periods. 

Figure 4 displays the annual, wintertime, and summertime average major PM2.5

speciation levels. On an overall annual basis, SO4 and OC account for about 27% and 

35%, respectively, of the reconstructed mass in New York City, roughly twice the 

contribution of NO3. During the winter months, OC is the largest contributor to the 

reconstructed mass (34%), while SO4 and NO3 also account for about 20%. The relative 

importance of NO3 is higher during the winter months because NO3 volatilization is 

much lower during the colder months. During the summer months, SO4 and OC levels 

are considerably higher than during the winter months, and account for about 70% of the 

reconstructed mass. The smallest components of reconstructed mass correspond to EC 

and crustal mass (~4-8%). On average, the reconstructed mass in New York City is 

about 18.2 μg m-3 during the summer months, and about 15.2 μg m-3 during the winter 

months. 

Summary

 The FRM data collected across the New York metropolitan area over the past 

seven years suggest that PM2.5 levels are generally higher in the core urban areas 

compared to the surrounding suburban counties. While this is a rather short time period, 

it appears that PM2.5 levels have been decreasing across the entire metropolitan area since 

the early 2000’s. In terms of species composition, SO4 and OC are the most important 

species, especially during the summer months, while NO3 is also an important species 

during the winter months. It appears that emissions control programs that target 

precursors of SO4, NO3, and OC will be needed to further reduce PM2.5 levels across the 

metropolitan area. 

Reference

United States Environmental Protection Agency (US EPA), 2007. Guidance on the use of 

models and other analyses for demonstrating attainment of air quality goals for ozone, 

PM2.5, and regional haze. Office of Air Quality Planning and Standards, 253 pp., EPA454/B-07-002.
Table 1. Listing of FRM sites, 1999-2006. Some locations have primary (“P”) and 

duplicate (“D”) samplers. Dates with an asterix denote daily sampling for at least part of 

the period. 

NYSDEC 

Region Site Name County Dates 

1 Eisenhower Park Nassau 1/1999 – 12/1999 

1 Hempstead Nassau 1/1999 – 12/2006 

1 Briarcliffe Nassau 2/2000 – 3/2003 

1 Roslyn Nassau 7/2000 – 3/2003 

1 Roslyn Heights Nassau 1/1999 – 3/2000 

1 Babylon Suffolk 1/1999 – 12/2006 

2 Mabel Dean H.S. New York 1/1999 – 6/2001* 

2 J.H.S. 45 New York P: 1/2000 – 12/2006 

D: 1/2006 – 12/2006 

2 P.S. 59 New York P: 1/1999 – 12/2006 

D: 1/1999 – 12/2005 

2 P.S. 19 New York 10/2001 – 12/2006 

2 Canal Street Post Office New York P: 1/1999 – 12/2006 

D: 8/1999 – 9/2001 

2 I.S. 155 Bronx P: 1/1999 – 7/1999 

D: 1/1999 – 7/1999 

2 Morrisania II Bronx 1/1999 – 12/2006 

2 N.Y. Botanical Gardens Bronx 1/1999 – 12/2006 

2 I.S. 52 Bronx P: 9/1999 – 12/2006* 

D: 9/1999 – 12/2006 

2 Greenpoint Kings P: 1/1999 – 12/2000 

D: 1/1999 – 7/1999 

2 P.S. 321 Kings 1/1999 – 3/2003 

2 P.S. 314 Kings 4/2000 – 1/2003 

2 J.H.S. 126 Kings 1/2001 – 12/2006 

2 Queensboro Community College Queens 1/1999 – 12/2000 

2 P.S. 29 Queens P: 7/1999 – 1/2003 

D: 8/1999 – 1/2003 

2 P.S. 214 Queens 4/2000 – 3/2003 

2 Queens College II/P.S. 219 Queens 1/2001 – 4/2006* 

2 Susan Wagner H.S. Richmond 1/1999 – 12/2006 

2 Port Richmond Post Office Richmond 12/1999 – 12/2006 

3 Poughkeepsie Dutchess 7/1999 – 3/2003 

3 Newburgh Orange 2/2000 – 12/2006 

3 Mamaroneck Westchester 2/2000 – 12/2006 
Table 2. Annual average PM2.5 levels for sites with at least 75% valid samples in a given 

year, 2000-2006. Incomplete years are left blank. 

Site Name 2000 2001 2002 2003 2004 2005 2006 

Hempstead 12.29 12.86 11.35 12.37 11.28 12.38 10.91 

Briarcliffe 12.73 12.44 11.27 

Roslyn 12.25 11.28 

Babylon 12.66 13.02 11.43 11.78 10.68 12.09 10.41 

Mabel Dean H.S. 16.71 

J.H.S. 45 (P) 15.52 15.18 14.12 14.35 13.12 14.51 12.63 

J.H.S. 45 (D) 12.77 

P.S. 59 (P) 18.42 17.95 15.88 15.63 16.96 14.60 

P.S. 59 (D) 18.38 18.01 16.22 15.76 16.81 

P.S. 19 15.62 15.94 15.10 15.59 13.79 

Canal Street Post Office (P) 17.57 17.13 15.42 15.76 14.43 15.45 12.76 

Canal Street Post Office (D) 17.36 

Morrisania II 16.73 15.92 15.34 15.58 14.39 16.38 14.40 

N.Y. Botanical Gardens 14.30 14.35 13.46 13.35 12.80 13.87 12.72 

I.S. 52 (P) 15.10 15.65 14.25 14.76 13.72 13.78 12.84 

I.S. 52 (D) 15.35 14.74 14.46 14.82 13.53 14.82 12.88 

Greenpoint 16.30 

P.S. 321 14.88 15.06 13.28 

P.S. 314 16.29 13.95 

J.H.S. 126 15.24 14.04 14.19 14.06 15.08 12.97 

Queensboro Community College 13.04 

P.S. 29 (P) 14.08 13.52 

P.S. 29 (D) 13.86 13.73 

P.S. 214 14.00 13.11 

Queens College II/P.S. 219 12.78 13.48 12.16 12.18 

Susan Wagner H.S. 12.44 13.00 10.84 11.35 12.15 10.45 

Port Richmond Post Office 14.31 14.46 13.83 13.33 14.36 12.03 

Poughkeepsie 11.31 11.18 10.73 

Newburgh 11.90 11.58 11.07 11.84 10.48 12.14 9.81 

Mamaroneck 12.62 12.93 11.76 12.14 11.33 12.46 11.11 
Table 3. The 98th percentile of PM2.5 levels for sites with at least 75% valid samples in a 

given year, 2000-2006. Incomplete years are left blank. 

Site Name 2000 2001 2002 2003 2004 2005 2006 

Hempstead 32.1 31.2 31.9 39.3 30.8 35.1 33.0 

Briarcliffe 34.0 32.5 30.7 

Roslyn 32.2 30.3 

Babylon 31.8 34.1 30.9 38.8 30.9 34.3 31.9 

Mabel Dean H.S. 42.9 

J.H.S. 45 (P) 40.8 35.8 35.5 46.2 38.0 36.6 37.6 

J.H.S. 45 (D) 37.8 

P.S. 59 (P) 41.7 40.4 35.6 41.1 40.1 40.7 

P.S. 59 (D) 42.1 39.8 35.5 41.4 39.5 

P.S. 19 35.8 48.5 38.9 36.5 36.8 

Canal Street Post Office (P) 41.4 38.2 33.6 46.2 39.1 39.5 35.9 

Canal Street Post Office (D) 41.0 

Morrisania II 40.1 36.7 35.2 44.8 38.2 37.7 41.5 

N.Y. Botanical Gardens 39.0 35.0 33.4 38.2 31.3 36.6 39.8 

I.S. 52 (P) 40.5 38.9 40.6 39.1 33.9 36.8 38.7 

I.S. 52 (D) 40.3 35.2 36.8 46.0 38.2 38.0 38.1 

Greenpoint 41.7 

P.S. 321 42.0 34.6 31.2 

P.S. 314 36.5 31.9 

J.H.S. 126 34.9 33.8 46.2 36.9 38.1 37.7 

Queensboro Community College 32.8 

P.S. 29 (P) 35.7 36.2 

P.S. 29 (D) 38.0 35.8 

P.S. 214 36.8 33.0 

Queens College II/P.S. 219 37.4 39.0 33.4 34.0 

Susan Wagner H.S. 33.0 31.4 24.3 33.5 32.1 32.0 

Port Richmond Post Office 39.8 31.9 39.3 31.3 37.2 36.2 

Poughkeepsie 30.8 27.6 31.2 

Newburgh 29.8 27.8 30.5 31.3 27.4 29.6 31.7 

Mamaroneck 34.9 33.5 32.5 36.8 33.5 32.8 34.4 
Table 4. Trends in PM2.5 mass at the longest running FRM monitors, based on quarterly 

averages from 1999-2006, in μg m-3 yr

-1. Only those quarters with at least 10 valid 

samples are included in this trend estimate. 

Site Name Trend (μg m-3 yr-1) 

Hempstead -0.12 

Babylon -0.34 

J.H.S. 45 -0.42 

P.S. 59 -0.30 

Canal Street Post Office -0.50 

Morrisania II -0.27 

N.Y. Botanical Gardens -0.15 

I.S. 52 (P) -0.33 

I.S. 52 (D) -0.23 

Susan Wagner H.S. -0.13 

Port Richmond Post Office -0.20 

Newburgh -0.20 

Mamaroneck -0.20 

Table 5. Listing of Speciation Trends Network (STN) sites, 2000-2006. All sites are 

located in NYSDEC Region 2. 

Site Name County Dates 

Canal Street Post Office New York 8/2002 – 12/2006 

N.Y. Botanical Gardens Bronx 2/2000 – 12/2005 

I.S. 52 Bronx 1/2001 – 12/2006 

Queens College II/P.S. 219 Queens 4/2001 – 12/2006 
Figure 1. Map of FRM sites. 

S#

S#

S# S#S#

S# S#

S#

S#

S#

S#

S#

S#

S#

S#

S#

S#

S#

S# S#

S#

S#

S#

S#

S#

S#

S#

S#
Figure 2. Annual average PM2.5 mass at FRM sites by NYSDEC Region. 

Annual average FRM PM2.5 by NYSDEC Region - all sites

0

2

4

6

8

10

12

14

16

1999 2000 2001 2002 2003 2004 2005 2006

PM 2.5 , μg m -3

Region 1 Region 2 Region 3

NAAQS 15 μg m-3

Figure 3. Seasonal variation in PM2.5 mass at FRM sites, by NYSDEC Region. 

Seasonal average FRM PM2.5 by NYSDEC Region - all sites

0

2

4

6

8

10

12

14

16

Quarter 1 Quarter 2 Quarter 3 Quarter 4

PM2.5, 

μg m -3

Region 1 Region 2 Region 3

NAAQS 15 μg m-3
Figure 4. Average PM2.5 speciation – annual, winter (DJF), and summer (JJA). 

Major components of PM2.5 mass at STN sites

0

1

2

3

4

5

6

7

SO4 NO3 NH4 EC OCB crustal

mass (

μg m -3)

Annual Winter Summer