## TSD- 3a

Analysis of Ambient PM 2.5 

## Mass and Speciation

for the New York Metropolit an 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, 2007Introduction

With the promulgation of the annual and daily PM 2.5 national ambient air quality standards (NAAQS) in 1997, the New York State Department of Environmental Conservation (NYSDEC) initiated monitori ng this pollutant on a statewide basis beginning in 1998/1999. A majority of the moni toring efforts to date have involved 24- hour, filter-based Federal Reference Met hod (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 require ments, several FRM sites have collocated duplicate samplers.

The PM 2.5 NAAQS is mass-based, but ambient PM 2.5 has a complex morphology and chemical composition. In order to obt ain 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 provi des for the concentration of major ions, carbon compounds, and trace elements, which generally constitute the bulk of PM 2.5
mass.

Although time series of ambient PM 2.5 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 addi tion to characterize current ambient levels. Here we present such tre nds on a composite basis over the New York portion of the New York City PM 2.5 non-attainment area (NYC NAA), corresponding to Bronx, Kings, Nassau, New York, Orange, Queen s, Richmond, Suffolk and Westchester Counties. All data used in this analysis are publicly available on the NYSDEC Division of Air Resources’ ambient PM 2.5 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-regi ons that cover parts of the NYC NAA: Region 1 (Long Island; 6 sites), Region 2 (N ew York City; 19 sites), and Region 3 (Lower Hudson River Valley; 3 sites). Th e 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 aver age FRM mass by NYSDEC region, using all valid data from 1999-2006. The averages presen ted in Figure 2 do not represent design values for attainment/regulatory purpo ses; however, the annual NAAQS of 15 μ g m -3 is shown for reference. This figure illustrates that on average, PM 2.5 is higher in Region 2 than the surrounding areas. Whereas the aver age levels in New York City range from about 13-15 μ g m -3 , the average levels in the surrounding counties is about 10-12 μ g m -3

.One other feature evident in Figure 2 is that PM 2.5 levels in the most recent few years are generally lower than levels measured in 1999-2001.

Figure 3 displays the composite seasona l/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 part iculate formation. In Region 2 the PM 2.5 levels are high in during both the warm and cold seas ons. The high levels during the colder months are likely indicative of local sources in the New Yo rk 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 98 th percentiles of FRM mass, respectively, from 2000-2006. Only those year s 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 ha ve four complete quarters. Similar to Figure 2, Table 2 indicates than on an average basis PM 2.5 levels are generally lower in the most recent years compared to earl ier years. In particular, average PM 2.5 levels in 2006 were generally the lowest in this seven-year period. The 98 th percentiles presented in Table 3 are related to the daily PM 2.5 NAAQS, which consists of the average of the 98 th percentile values over three consecutive years. Cu rrently the daily NAAQS is 65 μ g

m -3 , and Table 3 shows that all sites in the Ne w York metropolitan area have been well below this level.

Table 4 lists the linear trends in PM 2.5 mass at longest-running sites FRM sites in the New York metropolitan area. Th ese 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 da ta points were included in the linear trend estimates. Consistent with the composite averages presented earlier, PM 2.5 mass appears to be decreasing at each of these longest-running sites, by ~0.1-0.5 μ g m -3 yr -1

.

STN data

Table 5 lists the site locations and sampli ng periods of the STN monitors. Each of these sites is collocated with an FRM monito r. The STN samplers collect five ions – sulfate (SO 4 ), nitrate (NO 3 ), ammonium (NH 4 ), potassium (K), and sodium (Na) – nearly 50 trace elements, and various carbon sp ecies – elemental carbon (EC) and organic carbon (OC). For this analysis, we assume that PM 2.5 is primarily composed of only SO 4 , NO 3 , NH 4 , 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 PM 2.5 NAAQS is strictly mass-based, here we attempt to approximate the average species composition of the ambient PM 2.5 in NYC.

We adjusted the OC value by subtracti ng 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 μ g m -3 for MetOne SASS instruments(Canal Street Post Office, N.Y. Botanical Gardens) and 0.93 μ g m -3 for R&P 2300 ACCU instruments (I.S. 52, Queens Colle ge II/P.S. 219) is assumed (e.g., http://www.epa.gov/airtrends/aqt rnd03/pdfs/2_chemspecofpm25.pdf ). We then calculated the composite averag e of each of these component s across all four STN sites for all valid data points, as well as for just the winter (December-F ebruary) and summer (June-August) periods.

Figure 4 displays the annual, wintertime, and summertime average major PM 2.5 speciation levels. On an overall annual basis, SO 4 and OC account for about 27% and 35%, respectively, of the reconstructed ma ss in New York City, roughly twice the contribution of NO 3 . During the winter months, OC is the largest contributor to the reconstructed mass (34%), while SO 4 and NO 3 also account for about 20%. The relative importance of NO 3 is higher during the winter months because NO 3 volatilization is much lower during the colder mont hs. During the summer months, SO 4 and OC levels are considerably higher than during the winter months, and account for about 70% of the reconstructed mass. The sm allest components of reconstructed mass correspond to EC and crustal mass (~4-8%). On average, th e reconstructed mass in New York City is about 18.2 μ g m -3 during the summer months, and about 15.2 μ g m -3 during the winter months.

Summary

The FRM data collected across the Ne w York metropolitan area over the past seven years suggest that PM 2.5 levels are generally highe r in the core urban areas compared to the surrounding suburban counties. While this is a rather short time period, it appears that PM 2.5 levels have been decreasing acro ss the entire metropolitan area since the early 2000’s. In terms of species composition, SO 4 and OC are the most important species, especially during th e summer months, while NO 3 is also an important species during the winter months. It appears that emissions control programs that target precursors of SO 4 , NO 3 , and OC will be needed to further reduce PM 2.5 levels across the metropolitan area.

Reference

United States Environmental Protection Agen cy (US EPA), 2007. Guidance on the use of models and other analyses for demonstrating attainment of air quality goals for ozone, PM 2.5 , and regional haze. Office of Air Qu ality Planning and Standards, 253 pp., EPA454/B-07-002.Table 1. Listing of FRM sites, 1999-2006. So me locations have primary (“P”) and duplicate (“D”) samplers. Dates with an asteri x denote daily sampling fo r 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 – 12/2006Table 2. Annual average PM 2.5 levels for sites with at leas t 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 11.11Table 3. The 98 th percentile of PM 2.5 levels for sites with at least 75% valid samples in a given year, 2000-2006. Incomple te 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 34.4Table 4. Trends in PM 2.5 mass at the longest running FRM monitors, based on quarterly averages from 1999-2006, in μ g m -3 yr -1 . Only those quarters with at least 10 valid samples are included in this trend estimate.

Site Name Trend ( μ g 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 Netw ork (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 – 12/2006Figure 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

# SFigure 2. Annual average PM 2.5 mass at FRM sites by NYSDEC Region.

Annual average FRM PM 2.5 by NYSDEC Region - all sites

0 2 4 6 8 10 12 14 16

1999 2000 2001 2002 2003 2004 2005 2006PM2.5,μg m-3

Region 1 Region 2 Region 3 NAAQS 15 μ g m -3

Figure 3. Seasonal variation in PM 2.5 mass at FRM sites, by NYSDEC Region.

Seasonal average FRM PM 2.5 by NYSDEC Region - all sites

0 2 4 6 8 10 12 14 16

Quarter 1 Quarter 2 Quarter 3 Quarter 4PM2.5,μg m-3

Region 1 Region 2 Region 3 NAAQS 15 μ g m -3Figure 4. Average PM 2.5 speciation – annual, winter (DJF), and summer (JJA).

Major components of PM 2.5 mass at STN sites

0 1 2 3 4 5 6 7

SO4 NO3 NH4 EC OCB crustalmass (μg m-3)

Annual Winter Summer