Photochemical Assessment Monitoring Stations (PAMS)

The enhanced ozone precursor monitoring initiative, known as the PAMS program, is one of the most ambitions air quality monitoring programs ever attempted by the EPA and the States. The overall purpose of this long-term program (10+ years) is to monitor the changes in the atmospheric concentration of ozone precursors and to measure the effectiveness of current and future state and regional ozone precursor control programs. In addition, the data produced by the PAMS program will be used to enhance ozone modeling capabilities, help fine-tune state emission inventories, and provide measurements of toxic organic compounds that have been identified as Hazardous Air Pollutants (HAPs) by the 1990 Clean Air Act Amendments.

The PAMS monitoring network is a required monitoring component in ozone non-attainment areas that are classified as extreme, severe, or serious. In general, there are four different PAMS sites (Type 1 through Type 4) in each network, each of which serves a different purpose within the network. The Type 1 site measures ozone and its precursors upwind of the major metropolitan area, located in the ozone non-attainment area. The Type 2 sites measure ozone and its precursors immediately downwind of the metropolitan area, and are optimally located to characterize the complex "fresh" emissions that emanate from the metropolitan area. These sites operate on a more intensive sampling schedule than other PAMS sites, and are capable of measuring a larger array of ozone precursors than other PAMS sites. The Type 3 sites are located downwind of the metropolitan area, in the region of maximum ozone production. These sites generally record higher concentrations of ozone than upwind or near city PAMS sites. In addition, because the ozone and its precursor emissions have traveled downwind to these sites, the air masses arriving at these sites generally carry "aged" precursor emissions. Further downwind are the Type 4 sites, located from downwind of one or more metropolitan areas. These sites measure ozone precursor chemistry of extreme long-range ozone transport (to and within New England).

In the Northeast, non-attainment areas lay adjacent to each other, along the eastern seaboard. The abutting nature of these non-attainment areas and the common ozone and ozone precursor transport, which occurs across non-attainment areas, provide an opportunity to optimize the New England PAMS network and link it with upwind PAMS sites and research sites to the south and west. The New England PAMS network contains eighteen (18) PAMS sites. Figure 1 presents the approximate location of the PAMS sites in New England.

Most PAMS sites, which some exceptions, measure 56 different hydrocarbons (Table 5, located at the end of this section) on a hourly basis, twenty-four hours a day, during the heart of the summer (June through August). Hydrocarbon measurements are generally made using automated gas chromatography. At the primary Type 2 sites, carbonyls (aldehydes and ketones) are measured along with the hydrocarbon compounds. Composite samples of carbonyls are measured every three hours during the summer. All sites also measure ozone, oxides of nitrogen, and surface meterological conditions on an hourly basis. As the PAMS program matures, measurements of upper air meterological conditions will be made at key locations within New England as part of the PAMS network. Two upper air monitoring sites have been deployed in New England (mid-coastal Connecticut and western suburbs of Boston.)

1993 was the first year PAMS ozone precursor data were collected during the summer in New England. Quality control, and quality assurance (QA/QC) procedures for several PAMS instruments were under development in 1993, and few sophisticated computerized methods of data transfer and data troubleshooting were available. The field GCs proved temperamental during 1993, producing data of questionable accuracy. Because of this, most of the 1993 PAMS hydrocarbon and carbonyl data have not been entered into any national data base.

The 1994 and 1995 PAMS data have undergone much better QA/QC procedures, although data management issues and Acts-of-God (lightning strikes and electrical outages caused by storms) remain problems. In 1994, six PAMS sites operated throughout the summer, and several others underwent field deployment. In 1995, eight PAMS sites were operational and three additional sites were undergoing field deployment. The eight operating PAMS sites included: Cape Elizabeth, ME; Newbury/Plum Island, MA; Lynn, MA, Chicopee, MA, Quabbin Summit/Ware, MA; East Providence, RI; Stafford Springs, CT; and East Hartford, CT. Sites undergoing field deployment included: Westport/Sherwood Island, CT; Agawam, MA, and Easton/Borderland, MA. These latter three sites were deployed as combination Type 1/3 sites (Westport/Sherwood Island, CT and Easton/Borderland, MA) and a "stand alone" site (Agawam, MA Type 1 site). The Kittery, ME Type 2 site suffered contamination problems and additional start-up problems that nullified almost all of the 1995 data. In addition to these sites, the Truro, MA PAMS Type 4 site was deployed and operational as part of the North American Research Study of Tropospheric Ozone - Northeast (NARSTO-NE) field study.

In 1996 and 1997, four additional PAMS sites were deployed in the region. One was located in Acadia National Park (Type 4 site) as the far downwind PAMS site for New England. Another was located upwind of Providence, RI (West Greenwich, RI). Additional Type 2 sites were deployed in Boston (Long Island/Boston) and New Haven, CT. Table 1 presents a list of the 1997 PAMS sites which were operational or near deployed.

Map of Photochemical Assessment Monitoring Stations in New England 1997
Table 1. List of 1997 PAMS sites in New England, deployed or near operational
Site Location Map #PAMS Classification Status
Acadia National Park (ME) 17 Type 4 deployed 1996*
Cape Elizabeth (ME) 16 Type 3/4 deployed 1994
Kittery (ME) 15 Type 2 deployed 1995
Newbury/Plumb Island (MA) 7 Type 3 deployed 1994*
Lynn (MA) 6 Type 2 deployed 1993
Long Island/Boston (MA) 18 Type 2 deployed 1997*
Easton/Borderland Park (MA) 5 Type 1/3 deployed 1995*
Truro (MA) 8 Type 4 deployed 1995
West Greenwich (RI) 12 Type 1 deployed 1996*
East Providence (RI) 13 Type 2 deployed 1993*
Westport/Sherwood Island (CT) 1 Type 1/3 deployed 1996
East Hartford (CT) 2 Type 2 deployed 1993
New Haven (CT) 4 Type 2 deployed 1997*
Stafford Springs (CT) 3 Type 3 deployed 1994*
Agawam (MA) 9 Type 1 deployed 1995*
Chicopee (MA) 10 Type 2 deployed 1993*
Ware/Quabbin Summit (MA) 11 Type 3 deployed 1994
* these sites were deployed late in the PAMS season and data were not available until the following year.

A full assessment of the 1994 through 1997 PAMS data has not been conducted. Such an assessment is beyond the scope of this report. The 1994 data have been the subject of exploratory analysis by NESCAUM (Northeast States for Coordinated Air Management) and EPA. The following data presentation provides a cursory analysis of the 1995 through 1997 New England PAMS data base, exploring different features of the data. An extensive analysis of the 1995 through 1997 PAMS data will be conducted as part of the NARSTO-NE initiative (North American Research Strategy of Tropospheric Ozone - Northeast).

1995/1996/1997 PAMS Data

The following presentation provides information on the differences in concentration of biogenic VOCs, highly reactive VOCs, and toxic VOCs at the New England PAMS sites. In addition, a preliminary analysis of "aged" and "fresh" VOC emissions (as measured by the auto GCs) is presented for selected sites.

Chemical Changes in Air Mass

As polluted air moves over New England during the day, many of the compounds undergo photochemical reactions. The VOCs undergo chemical changes and hence the initial concentrations of these compounds change during the day. The more highly reactive organic compounds undergo chemical changes faster than slow reacting VOCs. It is possible to measure the "freshness" or "aged" characteristic of the air masses that pass over the PAMS sites by comparing the ratios of fast and slow reacting VOCs. Table 2 presents 1995 through 1997 data for fast and slow reacting VOCs. Previous studies have shown that toluene, benzene and m,p-xylene rations can provide useful measures of "fresh" (local) or "aged" (transported) air masses. M,p-xylene:benzene ratios less than 1.5 generally indicate an "aged" air mass, and rations ~1.5 generally indicate an air mass with "fresh" emissions. Likewise, benzene:toluene ratios >0.4 indicate an "aged" air mass, while those ~0.4 indicate "fresh" emissions. In general, subtle year-to-year differences in ratios can be anticipated in the data because of differences in summer meteorology and emissions patterns.

The New England PAMS sites have been located in up-wind, urban and downwind networks. The urban and downwind sites should provide data which help characterize/validate the "fresh" emissions or the "aged" nature of the VOCs measured at these sites. The PAMS data presented below for 1995, 1996, and 1997 clearly show that the downwind sites receive "aged" air. This is evident for the entire season (June-August), the peak ozone period of the day (1600-1800 hours), and during ozone episodes. In general the data for Chicopee (MA), and to some extent East Hartford (CT), appear to differ from those of the other Type 2 PAMS sites (Lynn and East Providence). This is expected given their location within the Connecticut River Valley in which south to north air flow commonly occurs during the summer. This air transport can deliver "aged" air from the lower part of the valley and southerly upwind emission sources. Hence, the ratio data indicate that these sites measure "aged" air during much of the ozone season. The data for the Westport, CT PAMS site suggests that this site, located downwind of the New York Metropolitan area, is influenced by "aged" and "fresh" emissions. This may be explained by intermittent transport and stagnant conditions that occur at this coastal site. Frequently, ozone precursor emissions are carried with prevailing winds along Long Island Sound from the NYC metropolitan area. During these conditions the air mass appears "aged". During other times local build up of ozone precursors, under somewhat stagnant conditions, occur and the air mass appears "fresh". It is not uncommon for transported and local precursors to mix.

During 1997, the data for the Type 3/4 and Type 2 sites suggest a stronger "fresh" influence, for the PAMS season, then the previous years, especially wen viewing the benzene:toluene ratios. This suggestion is further strengthened by the 1400-1600 hr period and the limited data recorded during ozone episodes.

Table 2. Measures of "aged" and "fresh" air masses at nine New England PAMS sites (1995-1997)
June-August 1400-1600 hr (June-August) Ozone Episodes (a)
Location m,p-X:Benz (b) Benz:Toluene (c) m,p-X:Benz (b) Benz:Toluene (c) m,p-X:Benz (b) Benz:Toluene (c)
199519961997 199519961997 199519961997 199519961997
Type 2 Sites
E Hartford 1.5 na 2.2 0.33 na 0.23 1.3 na 1.5 0.43 na 0.3 0.9,1.1 (k) 1.6,0.3 (k)
E Providence 1.8 1.5 1.8 0.26 0.27 0.22 1.6 1.8 1.6 0.32 0.31 0.27
Chicopee 1.3 1.4 2 0.24 0.29 0.3 0.8 1.1 1.1 0.31 0.36 0.39 0.21(d), 0.72 (l) 0.48(d), 0.35 (l)
Lynn 2.6 1.8 1.6 0.25 0.26 0.3 2.5 1.8 2 0.26 0.26 0.3 2.4 (e) 2.3 (e)
Type 3/4 Sites
Stafford Springs 1.1 1.2 1.1 0.45 0.46 0.33 1.2 0.8 0.68 0.59 0.54 0.43 0.21 (f) 0.59 (f)
0.39 (m) 0.15 (m)
Quabbin/ Ware 1 0.8 1.1 0.4 0.35 0.3 1.3 0.2 0.76 0.48 0.52 0.34 0.10 (g) 0.61 (g)
0.43 (n); 0.39, 0.9 (o) 0.41 (n); 0.38, 0.29 (o)
Newbury/ Plumb Island 1.1 1.5 1.7 0.41 0.32 0.29 1.2 2 1.2 0.58 0.35 0.35 na na
Cape Elizabeth 1.1 1.1 0.83 0.49 0.63 0.36 1 0.8 0.24 0.64 0.91 0.9 <0.15 (h) 0.5 (h)
0.73 (p), 0.67 (q)
Westport/ Sherwood Island na 1.4 1.4 na 0.36 0.32 na 1.1 1.1 na 0.35 0.39 1.4 (i) 0.4 (i)
>0.4 (j) 0.6 (j)
1.3, 1.67 (r); 0.2, 1.5 (s) 0.24, 0.25 (r); 0.5, 0.26 (?)
0.33 (t) 0.68 (t)

(a)
Hours during which the ozone standard (0.12 ppm O3) was exceeded
(b)
m,p-Xylene:Benzene ratios <1.5 indicate an "aged" air mass, rations ~1.5 or greater indicate a "fresh" air mass
(c)
Benzene:Toluene ratios >0.4 indicate an "aged" air mass, while ratios ~0.4 or less indicate a "fresh" air mass
(d)
June 30, 1995 @1700 hr.
(e)
August 1, 1995 @1700 hr.
(f)
July 13, 1995 @1600-1700 hrs.
(g)
August 10, 1995 @1600-1800 hrs.
(h)
August 1, 1995 @1500-1700 hrs.
(i)
?
(j)
?
(k)
?
(l)
?
(m)
June 21, 1997 @1300-2000 hrs; June 25, 1997 @1300-1700 hrs.
(n)
June 21, 1997 @1700-1900 hrs.
(o)
June 25, 1997 @1400-1600 hrs.
(p)
June 30, 1997 @1800-1900 hrs.
(q)
July 1, 1997 @1200-1400 hrs.
(r)
June 21, 1997 @1200-1400 and 1600 hrs.
(s)
July 14, 1997 @1500 hr and 1800 hr.
(t)
July 15, 1997 @1100-1700 hrs.

VOCs and Ozone

Previous analyses, conducted on PAMS data in New England and elsewhere, have shown that about twenty (20) of the measured PAMS VOCs generally account for 85% of the ozone produced in ambient air. These compounds and other VOCs are measured by the automated GCs at the PAMs sites. The table below lists the 20 major VOCs and their concentrations (ppbC) for nine PAMS sites in New England. These data (1995 through 1997) show that for almost all of the PAMS sites, whether Cape Elizabeth, Maine or East Providence, Rhode Island, the top five or six compounds (by concentration) remain virtually the same: ethane, isopentane, propane, toluene, n-pentane and n-butane (highlighted in bold in Table 3). The inland Type 2 and 3 sites, which are located near or within urban or rural forests, also show elevated concentrations of isoprene, a biogenic VOC. By far the highest concentrations of biogenic VOCs are recorded at the inland Type 3 sites (Quabbin Summit, MA and Stafford Springs, CT). During 1995, on particularly hot days, hourly isoprene concentrations exceeded 50 ppbC and approached 100 ppbC at these sites, dominating the organic precursors in the air. The cooler summer temperatures in 1996, however, resulted in lower concentrations of biogenic isoprene. Intermediate concentrations of isoprene were measured during 1997. As in previous years, inland sites such as Stafford Springs (CT) and Ware/Quabbin (MA) recorded the highest concentrations of isoprene within the New England PAMS network.

The greatest concentrations of these hydrocarbon compounds continue to be recorded at East Providence (RI), Lynn (MA) and East Hartford (CT). During 1997, the lowest concentrations of these compounds were recorded at Cape Elizabeth (ME), Ware/Quabbin and Newbury (MA), and Stafford Springs (CT).

Table 3. The summer average concentration (ppbC) of twenty ozone precursor VOCs measured at nine New England PAMS sites during June through August (1995 through 1997)
Cape Elizabeth Newbury Lynn East Providence East Hartford Stafford Springs Ware Chicopee Westport
199519961997 199519961997 199519961997 199519961997 19951996 199519961997 199519961997 (c) 199519961997 (d) 199519961997
Ethane 3 2.8 2.3 3 2.5 2.2 4.3 4.3 4 6.3 5.1 5.8 >2.8 na 3.2 3.3 2.6 2.7 3.2 2.2 4.1 3.8 4 na 3.7 2.8
Isopentane 2.4 2.3 2 2.2 4.2 2.3 6.4 6.6 4.4 7.7 6.1 6.5 11.6 na 2.7 2.6 2 2.3 1.8 1.6 9.4 6.1 4.6 na 5.2 4.3
Propane 2.9 2.5 2.5 3.3 3.1 2.5 3.6 3.7 3 6.2 5.3 5.5 5.5 na 2.7 2.9 2.6 2.1 2.3 1.8 3.9 3.7 3.5 na 4.1 4.1
Isoprene 1.7 0.8 1.8 2.4 1.3 2.1 4.3 3 3.9 2.7 2 2.8 2.4 na 5.6 4.4 4.7 16.1 7.4 8.5 4.5 3.5 2.7 na 2.4 2.5
Toluene 1.6 0.8 1.3 3.2 2.6 2.5 5.3 5.1 4.1 7 5.2 6.3 5.7 na 2.2 2.2 1.9 1.9 1.7 1.8 5.7 4 3.7 na 4.2 4.9
n-Butane 1.7 1.3 1.3 1.3 1.2 1 2.6 2.8 2.2 3.7 2.9 3.4 2.9 na 1.4 1.5 1.2 1.4 1.1 1.1 2.5 2.2 2 na 2.7 2.1
m/p-Xylene 0.7 0.6 0.4 1.4 1.2 1.2 2.9 2.4 1.9 3.3 2.1 2.4 2.4 na 1 1.2 0.7 0.8 0.5 0.6 1.6 1.6 2.3 na 2.1 2.2
n-Pentane 1 0.9 0.9 6.4 1.6 1.1 2.7 2.9 2.1 3 2.6 2.6 2.7 na 1.1 1.3 0.9 1.1 0.9 0.7 4.1 2.8 2.1 na 0.9 1.1
Ethylene 0.8 0.7 0.6 1.3 0.8 0.6 2.2 2.2 1.9 2.7 2.3 2.7 0.5 na 1 1 0.5 1.1 0.5 0.4 1.9 1.2 1.1 na 0.9 1.1
Benzene 0.8 0.5 0.3 1.3 0.8 0.7 1.3 1.3 1.2 1.9 1.4 1.4 1.9 na 1 1 0.6 0.8 0.6 0.5 1.3 1.1 1.1 na 1.5 1.5
Acetylene 1 0.4 0.4 0.5 0.6 0.2 1.8 1.7 1.3 2.5 1.9 2.3 1.7 na 0.8 1 0.2 0.6 0.4 0.4 0.8 0.7 0.8 na 1.2 0.5
2,2,4-TMP*** 0.6 0.3 0.5 1.4 1.2 0.7 1.7 1.6 1 1.5 1.4 1.3 1.5 na 0.9 0.7 0.5 0.9 0.4 0.4 1.3 1.4 1 na 1.7 1.6
Isobutane 0.7 0.6 0.6 0.8 0.6 0.4 1.1 1.3 1 2.4 1.9 2.4 1.5 na 0.8 0.8 0.6 0.9 0.6 0.5 1.3 1.1 1 na 1.5 1.1
1,2,3-TMB**** 0.6 0.3 0.8 0.7 0.7 0.6 1.3 0.5 0.7 0.3 0.2 0.2 0.9 na 0.8 0.3 0.6 <0.7 0.4 0.4 1 0.9 0.9 na 0.8 0.8
2-Methylpentane 0.6 0.6 0.6 1.2 1 0.7 1.8 1.8 1.4 2.9 2.3 2.3 na na 0.7 0.8 0.5 0.9 0.5 0.5 1.6 1.3 1.2 na 0.9 0.8
Propylene 0.5 0.5 0.6 0.9 0.4 0.3 1 0.9 0.8 1 0.8 1 3.4 na 0.7 0.4 0.4 1.2 0.3 0.2 0.9 0.5 0.6 na 0.9 0.9
1,2,4-TMB***** 0.2 0.1 0.1 1.6(a) 0.5 0.4 1.4 0.7 0.8 1.1 0.7 0.8 1.6 na 0.5 0.5 0.3 na 0.1 0.1 0.9 0.7 1 na 0.5 0.8
n-Hexane 0.5 0.3 0.5 1.3(b) 0.7 0.7 1.2 1.4 1.2 1.7 1.5 1.5 1.3 na 0.8 0.4 0.4 0.6 0.4 0.3 1.7 1.3 1.1 na 1 1.2
o-Xylene 0.2 0.2 0.2 0.9 0.6 1.4 1.2 0.9 0.7 1.2 0.8 0.9 1.2 na 0.6 0.5 0.3 0.4 0.2 0.3 0.9 0.7 0.8 na 0.8 0.9
p-Ethyltoluene 0.5 <0.1 <0.1 1.2(a) 0.3 0.4 0.7 0.4 0.2 0.4 0.3 0.3 0.7 na 0.5 0.3 0.3 <0.9 0.3 0.3 0.6 0.2 0.4 na 0.9 0.5
Sum of VOCs 22 17 18 32 26 21 52 46 38 60 47 52 49 na 29 27 22 36 23 23 50 36 36 na 39 36

*
local contamination problems invalidated July 1995 data
**
Site re-deployed in 1996
***
2,2,4-Trimethylpentane
****
1,2,3-Trimethylbenzene
*****
1,2,4-Trimethylbenzene
(a)
GC restart caused elevated concentrations (31 hours eliminated from the data used in this table)
(b)
<600 hours of data
(c)
August data undergoing re-evaluation
(d)
July data undergoing re-evaluation

Hazardous Air Pollutants and Urban Air Toxic Compounds

Table 4 presents the hourly average concentrations (ppbC) of hazardous organic air pollutants measured at PAMS sites for three summer months of 1996 and 1997. For consistency with the other data presented in this section, the data are presented as parts per billion carbon (ppbC). It is clear that the Type 2 sites, located within urban areas, measure atmospheres more rich in hazardous organic air pollutants (HAPs) than the Type 1/3/4 sites. Toluene, 1,2,4-Trimethylbenzene, benzene, m/p-Xylene, and 2,2,4-Trimethylpentane head the list of these hydrocarbons. Of the carbonyls, formaldehyde (1996 data only), is the most prevalent. This is due to the fact that formaldehyde is both directly emitted to the atmosphere from industrial activities and mobile sources (a source of many toxic air pollutants), and is one of the most common chemical reaction products of VOC photochemistry.

Table 4. The average summer (June-August) concentration (ppbC) of ten toxic organic compounds (TOC) measured at nine New England PAMS monitoring sites (1996 and 1997).
TOC Cape Elizabeth (ME) Newbury (MA) Lynn (MA) East Providence (RI) East Hartford (CT) Stafford Springs (CT) Ware/ Quabbin (MA) Chicopee (MA) Westport (CT)
19961997 19961997 19961997 19961997 1996*1997 19961997 19961997** 19961997*** 19961997
Formaldehyde (a) na na na na 3.2 2.8 na na na 4.7 2.4
Acetaldehyde (a) na na na na 1.1 1 na na na 1.2 1.6
Toluene 0.8 1.3 2.6 2.5 5.1 4.1 5.2 6.3 na 6.1 2.2 1.9 1.7 1.8 4 3.7 4.2
m,p-Xylene 0.6 0.4 1.2 1.2 2.4 1.9 2.1 2.4 na 2.9 1.2 0.7 0.5 1.6 1.6 2.3 2.1
Benzene 0.5 0.3 0.8 0.7 1.3 1.2 1.4 1.4 na 1.3 1 0.6 0.6 0.5 1.1 1.1 1.5
Propylene (b) 0.5 0.6 0.4 0.3 0.9 0.8 0.8 1 na 0.8 0.4 0.4 0.3 0.2 0.5 0.6 0.9
1,2,4-TriMB 0.1 0.1 0.5 0.4 0.7 0.8 0.7 0.8 na 1.4 0.5 0.3 0.1 0.1 0.7 1 0.5
o-Xylene 0.2 0.2 0.6 0.4 0.9 0.7 0.8 0.9 na 1.1 0.5 0.3 0.2 0.3 0.7 0.8 0.8
p-Ethyltoluene <0.1 <0.1 0.3 0.4 0.4 0.2 0.3 0.3 na 0.7 0.3 0.3 0.3 0.3 0.2 0.4 0.9
2,2,4-TriMP 0.1 0.1 1.2 0.7 1.6 1 1.4 1.3 1.7 0.7 0.5 0.4 0.4 1.4 1 1.7

*
no data were collected due to site re-deployment
**
re-evaluating August data
***
re-evaluating July data
(a)
carbonyl measurements were generally taken at PAMS Type 2 sites
(b)
this compound is also measured by the Urban Air Toxics Monitoring Program
Year-to-year changes in the concentration of these compounds are expected, due primarily to changes in major emission source strengths (from industry and motor vehicles) and changes in meteorological conditions. For the most part, the concentration of these air pollutants remained steady or decreased slightly from 1996 to 1997. The exceptions are: East Providence (RI), which experienced an increase in toluene (~20%), and Cape Elizabeth (ME) and Westport (CT), which also recorded slight (< 1.0 ppbC) increases in toluene. The cleanest sites are in the rural and remote areas (Stafford Springs [CT] and Ware/Quabbin [MA]). It is important to note that all of the sites record low to moderate levels of these pollutants.

PAMS Measurements

The PAMS program measures a host of compounds. Table 5 provides a list of the measurements made at PAMS sites. Many of these compounds are toxic. Most others contribute to the generation and accumulation of ozone. In addition, many of the measured compounds contribute to the formation of complex organic aerosols and fine particulate matter (PMf), which will become the focus of additional national, regional, and local (integrated) air pollution controls over the next decade. Changes in organic aerosol precursors will undoubtedly provide very useful measures of the effectiveness of future fine particle control programs.

Table 5. Reported hydrocarbon, carbonyl, and other aerometric measurements at PAMS sites in New England
Hydrocarbon Compounds
Ethane
Ethylene
Acetylene
Propylene
Propane
Isobutane
1-Butane
trans-2-Butene
cis-2-Butene
3-Methyl-1-Butene
Isopentane
1-Pentene
n-Pentane
Isoprene
trans-2-Pentene
cis-2-Pentene
2-Methyl-2-Butene
2,2-Dimethylbutane
Cyclopentene
2,3-Dimethylbutane
2-Methylpentane
3-Methylpentane
2-Methyl-1-Pentene
n-Hexane
trans-2-Hexene
Methylcyclopentane
2,4-Dimethylpentane
Benzene
Cyclohexane
2-Methylhexane
2,2,4-Trimethylpentane
n-Heptane
Methylcyclohexane
2,3,4-Trimethylpentane
Toluene
2-Methylheptane
3-Methylheptane
n-Octane
Ethylbenzene
m,p-Xylene
Styrene
o-Xylene
n-Nonane
Isopropylbenzene
n-Propylbenzene
m-Ethyltoluene
p-Ethylbenzene
1,3,5-Trimethylbenzene
o-Ethylbenzene
1,2,4-Trimethylbenzene
m-Diethylbenzene
p-Diethylbenzene
n-Decane
n-Undecane
TNMOC (HC)
Carbonyl Compounds
Formaldehyde
Acetaldehyde
Acetone
Inorganic Gases
Ozone
NO, NO2, NOx, NOy
Meterological Measurements
Wind Speed
Wind Direction
Solar Radiation
Ultraviolet Radiation
Barometric Pressure
Humidity

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Steven McDougall / swmcd@theworld.com / 1998 September 27