Emission factors and exposures from ground-level pyrotechnics

Atmospheric Environment 44 (2010) 3295e3303

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Emission factors and exposures from ground-level pyrotechnics Gerry Croteau a, *, Russell Dills a, Marc Beaudreau a, Mac Davis b a b

University of Washington, Department of Environmental and Occupational Health Sciences, 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105-6099, USA Washington Division of Occupational Safety and Health, USA

a r t i c l e i n f o

a b s t r a c t

Article history: Received 8 January 2010 Received in revised form 24 May 2010 Accepted 26 May 2010

Potential exposures from ground-level pyrotechnics were assessed by air monitoring and developing emission factors. Total particulate matter, copper and SO2 exposures exceeded occupational health guidelines at two outdoor performances using consumer pyrotechnics. Al, Ba, B, Bi, Mg, Sr, Zn, and aldehyde levels were elevated, but did not pose a health hazard based on occupational standards. Emission factors for total particulate matter, metals, inorganic ions, aldehydes, and polyaromatic hydrocarbons (PAHs) were determined for seven ground-supported pyrotechnics through air sampling in an airtight room after combustion. Particle generation ranged from 5 to 13% of the combusted mass. Emission factors (g Kg
1) for metals common to pyrotechnics were also high: K, 23e45; Mg, 1e7; Cu, 0.05e7; and Ba, 0.03e6. Pb emission rates of 1.6 and 2.7% of the combusted mass for two devices were noteworthy. A high correlation (r2  0.89) between metal concentrations in pyrotechnic compositions and emission factors were noted for Pb, Cr, Mg, Sb, and Bi, whereas low correlations (r2  0.1) were observed for Ba, Sr, Fe, and Zn. This may be due to the inherent heterogeneity of multi-effect pyro
technics. The generation of inorganic nitrogen in both the particulate (NO
2 , NO3 ) and gaseous (NO, NO2) forms varied widely (<0.1e1000 mg Kg
1). Aldehyde emission factors varied by two orders of magnitude even though the carbon source was carbohydrates and charcoal for all devices: formaldehyde (<7.0e82 mg Kg
1), acetaldehyde (43e210 mg Kg
1), and acrolein (1.9e12 mg Kg
1). Formation of lower molecular weight PAHs such as naphthalene and acenaphthylene were favored, with their emission factors being comparable to that from the combustion of household refuse and agricultural debris. Ba, Sr, Cu, and Pb had emission factors that could produce exposures exceeding occupational exposure guidelines. Sb and unalloyed Mg, which are banned from consumer fireworks in the US, were present in significant amounts. Ó 2010 Elsevier Ltd. All rights reserved.

Keywords: Consumer fireworks Pyrotechnics Exposure monitoring Emission factor

1. Introduction Aerial pyrotechnics are a source of airborne pollutants (Drewnick et al., 2006; Vecchi et al., 2008). In addition to aerosolized metals, used as fuel and coloration, a myriad of pyrolysis byproducts (e.g. NOx, SO2, and organic compounds) are generated. Given that the emissions generated by pyrotechnics are directly attributable to formulation, substances common to pyrotechnics and their function are reviewed. Ingredients in pyrotechnics function as fuels, oxidants, colorants, or binders (Shimizu, 2004; Steinhauser and Klapotke, 2008). Fuels include reactive metals (Mg, Al, Fe, Zn), carbon, carbohydrates (sucrose, lactose, starch), and sulfur. Atmospheric oxygen cannot support a rapid rate of combustion so an oxidant, typically a nitrate

* Corresponding author. Tel.: þ1 011 206 616 1907; fax: þ1 011 206 616 6240. E-mail address: [email protected] (G. Croteau). 1352-2310/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2010.05.048

or perchlorate salt, is included. Colors in pyrotechnic displays result from electron excitation of metal ions at high temperatures during combustion with Ba (green), Sr (red), Na (yelloweorange), and Cu (blue) being the most common (Conkling, 2001). Examples of binders are casein, gelatin, nitrocellulose, starch, and polyester. Additional compounds may be present for specialized functions (Shimizu, 2004) such as smoke generation (organic dyes), noise effects (metal salicylates), and color enhancement (chloride salts or chlorinated organics). Research characterizing emissions from pyrotechnics has largely focused on the collection of ambient air samples from monitoring stations encompassing aerial displays (Drewnick et al., 2006; van der Kamp et al., 2008; Kulshrestha et al., 2004; Moreno et al., 2007; Perry, 1999; Ravindra et al., 2003; Vecchi et al., 2008; Wang et al., 2007; Wehner et al., 2000). These studies as a whole found transient increases in airborne particulate matter and metals (K, Mg, Ba, Cu, Sr, Pb, Al, Mn, and Zn). Increases in SO2 (Moreno et al., 2007; Ravindra et al., 2003; Wang et al., 2007), NO

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(Moreno et al., 2007; Wehner et al., 2000), NO2 (Ravindra et al., 2003; Wang et al., 2007), ozone (Attri et al., 2001), and organic compounds (Wang et al., 2007; Drewnick et al., 2006) were also noted. Particulate and gas phase components typically declined to background levels within a day. Particles had a mean aerodynamic diameter less than 1.0 mm (Perry, 1999; Vecchi et al., 2008; Wang et al., 2007; Dutschke et al., 2009), and hence were respirable. Although these studies found a 5e20 fold increase over background levels for many pollutants, the concentrations were low and short-term (24 h), suggesting minimal risk to public health. PM2.5 concentrations in several studies (Ravindra et al., 2003; Kulshrestha et al., 2004) were greater than local air quality standards, but individual pollutants were not. Despite ambient SO2 concentrations increasing up to a factor of ten during Diwali celebrations in Hisar, India (Ravindra et al., 2003), the highest concentration (0.01 ppm), was 50 times less than the concentration that can trigger an asthmatic response (Gong et al., 1995). These studies measured ambient contaminants not proximal personal exposures. The characteristics of the display and the proximity of the technicians, spectators, and performers are important factors influencing exposure and hence potential health effects. Clearly an event solely of aerial fireworks (classified as 1.3 G by the U.S. Department of Transportation) represents a minimal exposure potential as the display is not only several hundred feet away, but also offers substantial potential for atmospheric dispersion. In contrast, exposure levels for spectators, technicians, and performers at an event using consumer fireworks (designated 1.4 G) at ground level are considerably greater, especially at an indoor event. Thus, the ensuing risk for health effects are considerably greater at ground-level displays. Moreover, the consumption of consumer fireworks is considerably greater than that of display fireworks; 239 million pounds of consumer fireworks were deployed in the United States compared to 27 million pounds of display fireworks in 2007 (APA, 2007). Combustion products that cause acute respiratory effects over short exposure durations in low concentrations are especially a concern. Known respiratory irritants associated with pyrotechnic displays include O3, SO2, NO2, NO, HCl, acrolein, and formaldehyde. At a concentration of just 0.5 ppm SO2 can trigger an asthmatic response in a susceptible individual (Gong et al., 1995) and may have been the causal agent for a reported fatality of an asthmatic child that was using sparklers (Becker et al., 2000). Likewise, shortterm exposure to the other compounds can elicit a respiratory response (ACGIH, 2001). The personal exposure to toxicants generated during surface level or indoor displays has received very little attention (Dutcher et al., 1999; Dutschke et al., 2009) and no personal monitoring has been performed. Fortunately, exposure for most individuals engaging in the use or enjoyment of a ground-level display is likely limited to a few hours for a few events per year. Exceptions are performers and technicians exposed during pyrotechnic performances (Supplementary information, Video A1) where the use of pyrotechnics ranges from incidental to performances centered on pyrotechnics. To better understand the overall health hazard associated with ground level, consumer grade pyrotechnics, we performed an exposure assessment and determined emission factors for selected pyrotechnics.

2. Methods 2.1. Bulk sample collection and analysis Approximately 10 g of the pyrotechnic charge was transferred to a glass vial for analysis by standard methods (Table 1). Prior to bulk sample collection, each pyrotechnic was analyzed for metals with

Table 1 Analytical Methods. Analyte

Method

Reference

Total particulate matter Metals

Gravimetric Hot Block digestiona Microwave digestion ICPMS Ion chromatography GC/MS with stable isotope dilution Ion chromatography Ion chromatography High-pressure liquid chromatography Ion chromatography Thermal desorption and GC/MS

NIOSH 0500b NIOSH 7303b EPA 3051Ac EPA 6020Ac OSHA ID-215, rev 2d EPA 8270Dc

Cr(IV) PAH NO & NO2 SO2 Carbonyls Inorganic acids Organic volatile screen a b c d e f

OSHA ID-190e NIOSH 6004b NIOSH 2016b NIOSH 7903b EPA TO-17f

Hot block digestion was used for the exposure assessment air samples. NIOSH, 1994. U.S. EPA, 2007. OSHA, 2006. OSHA, 1991. U.S. EPA, 1999.

a Niton 700 portable X-ray fluorescence spectrometer (1 min acquisition, 10 mCi 109Cd source; Niton, Billerica, MA). 2.2. Exposure monitoring Exposure monitoring was conducted during two outdoor performances (described in Supplementary information) by the troupe, Cirque de Flambé. Personal air samples were collected in the performers breathing zone, using accepted occupational exposure sampling methods (described in Supplementary information), while area samples were collected at the rear wall about 7 m from the center of activity at a height of 1.5 m. Measured exposures were compared to the threshold limit values (TLVs), occupational exposure guidelines developed by the American Congress of Governmental Industrial Hygienists (ACGIH, 2009). These exposure guidelines are not necessarily protective of the most susceptible individual such as those sensitized to a contaminant. The TLVs were chosen as a basis for assessing exposure data given that technicians and performers in close proximity to ground-level pyrotechnics were likely most exposed. 2.3. Emission factor development Burns for the development of emission factors took place inside a concrete block room (41.2 m3) at the City of Renton Fire Department’s Training Facility. The room could be rapidly cleared after each burn by activating the facility’s exhaust system. A test run was conducted to ensure the room was tightly sealed, which was confirmed by the absence of any smoke escaping from the room. Each device was positioned in the middle of the floor on preweighed aluminum foil (60  90 cm) and then ignited. Seven different pyrotechnics were tested, two in duplicate. The pyrotechnic was observed by closed circuit television from an adjacent control room, allowing the burn time to be determined. Air sampling commenced 2 min after burnout, to enable a reasonably homogenous distribution of the particulate and gas phase emissions within the room. Tubing connecting sampling pumps in the control room to various air-sampling media inside the burn room passed through an airtight bulkhead. Air samples were collected for 15 min from a single location, 2.0 m from an adjacent wall at a height of 1.5 m using methods described in Supplementary information. Homogeneity of generated particulate matter and gasses was assessed in a separate experiment by collecting samples for metals analysis near each corner.

G. Croteau et al. / Atmospheric Environment 44 (2010) 3295e3303

The initial and residual weights after combustion were determined. Remains (external packaging, refractory material, and internal cardboard and plastic structural components) were manually collected. The mass of combusted residue near the pyrotechnic was determined from the weight gain of the underlying aluminum foil. The mass of the remaining deposited combusted residue was determined after being recovered by carefully sweeping the room. 2.4. Sample analysis Analyses were performed by a laboratory accredited through the American Industrial Hygiene Association using standard analytical procedures (Table 1). The full screen of metals and metalloids by inductively coupled plasma mass spectrometry (ICPMS) provided a basis for selecting metals for emission factor generation. Portable X-ray fluorescence spectrometry was evaluated for accuracy in determining elemental content of pyrotechnics in situ against ICPMS analysis. 3. Results and discussion 3.1. Pyrotechnic composition Chemical analysis of 12 pyrotechnics by ICPMS (Table 2), confirmed that colorants (Ba, Cu, Sr) and combustion agents (Al, Fe,

3297

Mg) were the predominate metals. The concentration of the other metals varied considerably between devices, which was likely a reflection of these metals being used for specialized effects such as generation of smoke (Zn) or glitter (Sb). Projectiles from three examples of Roman candles had two basic compositions (Table 2). Roman Candle A; minimal Mg fuel (0.05%), Ba colorant (0.1%), and 66 mg g
1 Zn; Roman Candle B and C: MgeAl fuel (3e14%) and 2e4% colorant, Cu, Ba, or Sr. Significantly, the first composition contained Li (100 mg g
1) and Be (25 mg g
1). A possible explanation for the presence of these two elements would be the presence of Mg alloys (Pekguleryuz, 2006). This was also the only pyrotechnic analyzed to use Mg without Al. Mg is attacked under acidic conditions in pyrotechnics unlike Al or MgeAl alloys (Conkling, 2001) and was banned from pyrotechnics in the US unless alloyed with Al (CFR, 1976). Components producing a whistle were incorporated into multitube pyrotechnics. Alkali salts of organic acids (e.g. benzoic or salicylate) combined with an oxidizer are typical ingredients (Conkling, 2001; Shimizu, 2004). The whistle components in this study may have been designed to produce sound and visual effects since Mg, Al, and colorants were present in significant quantities. Pb comprised 13% of one component albeit the charge in this whistle was small (80 mg). One whistle contained Sb, also prohibited by CFR 1976, at 3% and was likely Sb2S3. The Pb concentration in three devices, fountain, ribbon fuse, and dragon egg exceeded 5%. Lead (typically Pb3O4) may be present for

Table 2 Metal content of pyrotechnics (mg kg
1). Device

Al

B

Ba

Bi

Cu

Cr

Fe

Dragon Eggs Road Flare Ribbon Fuse Sparkler Pinwheel

6 chambers

8.76Eþ04 4.77Eþ02 5.65Eþ03 2.97Eþ02 1.77Eþ04

<9.50Eþ02 <1.86Eþ03 <7.20Eþ02 6.00Eþ00 <1.55Eþ02

2.58Eþ04 6.72Eþ03 1.33Eþ04 4.40Eþ01 2.20Eþ01

1.70Eþ00 3.80Eþ01 1.10Eþ01 <2.00Eþ00 2.00Eþ00

9.12Eþ04 3.46Eþ02 1.61Eþ04 1.90Eþ01 8.72Eþ03

1.00Eþ03 3.60Eþ01 3.90Eþ00 <4.00Eþ00 1.19Eþ02

5.19Eþ02 <1.01Eþ02 2.81Eþ02 <3.30Eþ01 9.64Eþ03

Roman Roman Roman Roman

Lift charge Projectile Projectile Projectile

3.88Eþ02 <5.32Eþ03 1.42Eþ04 7.68Eþ04

<1.39Eþ03 <5.32Eþ04 <4.96Eþ03 <3.46Eþ03

2.80Eþ01 1.12Eþ03 2.00Eþ01 2.10Eþ04

<4.00Eþ00 <1.35Eþ02 1.81Eþ03 4.00E-01

<5.70Eþ01 < 2.19Eþ03 4.14Eþ04 2.17Eþ03

<9.00Eþ00 <3.43Eþ02 5.00Eþ00 5.60Eþ01

5.57Eþ02 <2.88Eþ03 7.18Eþ02 1.05Eþ03

6 7 2 1 3 1 1 1

5.27Eþ04 3.59Eþ04 9.19Eþ03 2.21Eþ04 3.61Eþ03 1.58Eþ04 1.33Eþ04 >1.21Eþ05

e e 4.38Eþ02 <1.33Eþ03 <7.35Eþ03 <7.43Eþ02 2.97Eþ00 <6.93Eþ02

1.56Eþ04 1.01Eþ04 2.72Eþ03 2.51Eþ04 9.80Eþ01 8.00Eþ00 1.79Eþ04 1.09Eþ04

4.33Eþ02 2.20Eþ02 <3.00Eþ00 <3.00Eþ00 <1.90Eþ01 2.85Eþ03 <1.00Eþ00 <2.00Eþ00

2.90Eþ04 1.72Eþ04 1.00Eþ4 1.63Eþ02 5.96Eþ03 1.70Eþ04 3.85Eþ03 1.30Eþ03

3.15Eþ02 5.93Eþ02 2.30Eþ01 1.48Eþ02 <5.70Eþ01 3.00Eþ00 <2.00Eþ00 2.20Eþ01

2.02Eþ03 2.05Eþ03 4.83Eþ02 1.29Eþ03 2.89Eþ02 2.42Eþ02 7.80Eþ01 5.38Eþ02

Li 2.00Eþ00 <1.30Eþ01 <5.00Eþ00 2.00Eþ00 1.40Eþ00

Mg 6.09Eþ04 5.84Eþ02 6.06Eþ03 1.25Eþ04 1.48Eþ04

Mn 3.00Eþ02 6.00Eþ00 2.69Eþ02 3.60Eþ01 3.45Eþ01

Ni 1.20Eþ01 <1.20Eþ01 2.00Eþ00 2.00Eþ00 1.32Eþ02

Pb 5.23Eþ04 <1.00Eþ00 7.55Eþ04 <3.00Eþ00 3.00Eþ00

Sb 7.57Eþ03 <1.13Eþ02 4.30Eþ01 <3.70Eþ01 3.17Eþ02

Sr 3.28Eþ02 >2.31Eþ05 9.50Eþ01 1.60Eþ04 8.72Eþ03

Zn 5.58Eþ02 1.50Eþ01 3.68Eþ02 1.14Eþ02 2.97Eþ02

4.00Eþ00 1.18Eþ02 1.00Eþ00 8.00Eþ00

2.62Eþ02 5.57Eþ02 1.26Eþ04 6.20Eþ04

3.40Eþ01 <3.06Eþ02 1.11Eþ02 4.91Eþ02

<9.0Eþ00 <3.34Eþ02 6.00Eþ00 3.50Eþ01

<7.00Eþ00 <2.77Eþ02 2.00Eþ01 4.04Eþ02

<8.50Eþ01 <3.24Eþ03 4.71Eþ02 1.24Eþ03

1.10Eþ01 <6.30Eþ01 9.00Eþ00 4.69Eþ04

1.30Eþ01 6.60Eþ01 8.80Eþ01 4.21Eþ03

e e 4.00E-01 1.30Eþ00 <4.90Eþ01 2.00E-01 6.00E-01 1.00E-01

2.90Eþ04 2.09Eþ04 8.32Eþ03 2.61Eþ04 2.14Eþ04 1.32Eþ04 2.12Eþ04 2.66Eþ04

7.30Eþ02 6.68Eþ02 2.15Eþ02 5.20Eþ02 6.20Eþ01 2.82Eþ02 4.20Eþ01 5.21Eþ02

e e 2.50Eþ00 4.00Eþ00 <4.60Eþ01 6.00Eþ00 3.00E-01 1.10Eþ01

7.80Eþ01 <4.20Eþ01 1.20Eþ01 1.65Eþ02 <3.80Eþ01 9.05Eþ04 1.00E-01 6.80Eþ01

<1.60Eþ01 <4.20Eþ01 1.10Eþ01 2.86Eþ02 1.34Eþ04 2.19Eþ03 2.15Eþ02 2.50Eþ01

2.66Eþ03 1.35Eþ03 2.39Eþ03 1.26Eþ02 2.58Eþ02 1.00Eþ01 1.04Eþ04 7.80Eþ01

2.35Eþ03 3.77Eþ03 2.06Eþ02 5.91Eþ02 3.84Eþ02 2.20Eþ01 2.50Eþ01 1.23Eþ03

Candle A Candle A Candle B Candle C

Fountain Fountain Fountain Fountain Fountain Fountain Fountain Fountain

A B C D E F G H

Device Dragon Eggs Road Flare Ribbon Fuse Sparkler Pinwheel Roman Roman Roman Roman

Candle Candle Candle Candle

Fountain Fountain Fountain Fountain Fountain Fountain Fountain Fountain

A B C D E F G H

A A B C

chambers chambers chambers chamber chambers chamber chamber chamber

Maximum levels of metals not presented: As 31 mg kg
1 (Pinwheel); Se 10 mg kg
1 (Roman Candle A projectile); Co 2.1 mg kg
1 (Pinwheel); Be 25 mg kg
1 (Roman Candle A projectile); Cd 10 mg kg
1 (Roman Candle A projectile) Mean levels presented for multi-chambered devices.

2000 6000 50 na na na 50 150 500 1500 200 600 10,000 30,000 ACGIH 8-h TLVb ACGIH STELTLVc

— ¼ not measured. Event 1: Li, Be, Ti, Co, Ni, As, Se, Zr, Mo, Ag, Tl less than quantification limit (8 mg m
3). Event 2: Co, Ni, less than quantification limit (10 mg m
3). a Total airborne particulate matter. b American Congress of Governmental Industrial Hygienists 8-h time weighted average Threshold Limit Value. c American Congress of Governmental Industrial Hygienists 8-h time weighted average short-term (15 min) exposure limit.

5000 15,000 200 600 500 1500 10 30 na na 500 1500 na na 1000 3000 10 30

<2 14 35 28 <8 <0.2 <1 3 3 <8 <0.1 120 230 260 12 <2 <1 <2 <3 <1 e e e e e <0.1 3 9 8 < 0.4 <1 530 1300 1100 48 5 <10 <20 <30 <8 2 10 1100 1100 20 <0.3 3 16 16 <2 <0.1 <1 1 2 <0.4 e e e e e e e e e e Area A, Entire show Area A, Finale Personal, Finale Area B, Finale Area C, Entire show 2

78 10 27 23 76

e e e e e

<2 260 800 570 20

e e e e e

e e e e 6 <8 10 <8 <3 <8 <8 <8 <3 <8 200 <8 <3 <8 <8 <8 60 200 58 <8 <20 <50 <50 <50 <3 <8 <8 <8 <3 <8 <8 <8 10 60 <8 <8 Personal A, Finale Personal B, Finale Area A, Finale Area B, Finale

18 6 4 4

7.45 18.96 1.23 5.61

30 90 <8 <8

30 100 20 <8

7 20 20 <8

Cr mg m
3 Cd mg m
3 Bi mg m
3 Ba mg m
3 B mg m
3 Al mg m
3 TPa

mg m
3

Period min

1

Emission factors were developed for seven different devices, which included four brands of fountains, dragon eggs (pyrotechnic stars), ribbon fuse and a roman candle. The burn time for the devices were relatively short, ranging from 23 to 151 s (Table 5). For five of the tested devices, a relatively large fraction, 55e86% of the initial mass, remained as non-combusted residue (Table 5). This

Sample

3.3. Emission factor determination

Table 3 Total Particulate matter and Metal Exposure Monitoring Results.

A total of three personal and six area samples were collected during two performances. Overall exposure levels were low for particulate (Table 3) and gas analytes (Table 4). Many exposure measurements were less than quantification limits and below the respective ACGIH 8-h time weighted average (TWA) TLV. Total particulate matter levels at event 1 ranged from 1.23 to 18.96 mg m
3, the latter being almost twice the ACGIH 8-h TWA TLV. No metals exceeded the 8-h TLV in event 1. Only copper exceeded the 8-h TLV in event 2; a performer had a personal copper exposure of 1100 mg m
3, which at five times the 8-h TLV, also exceeds the Short-Term Exposure Limit-15 min (STEL). Other metals, with the exception of aluminum (80% of TLV), did not exceed 40 percent of their TLV. The substantial differences in personal monitoring results for Cu, Al, Mg, Sr, and Zn between the two events reflect the use of different pyrotechnics in the two performances. Gas and vapor analytes, including polycyclic aromatic hydrocarbons (PAHs), carbonyls, CO, NO2 and SO2, were near or below their respective quantification limits (Table 4). Carbonyl compounds were not detected during the first event, but during the second event formaldehyde and acetaldehyde were at very low concentrations, less than 10 percent of the ceiling level TLV. Carbon monoxide levels during the first performance ranged from 2 to 10 ppm, considerably less than ACGIH 8-h and STEL guidelines. Sulfur dioxide, which ranged from 1.5 to 7 times the ceiling limit TLV, is a concern, as this compound is a known respiratory irritant that quickly causes bronchoconstriction in asthmatics at concentrations as low as 0.5 ppm (Gong et al., 1995).

Cu mg m
3

3.2. Exposure monitoring

80 200 <50 <50

Fe mg m
3

Mg mg m
3

Mn mg m
3

Sb mg m
3

Pb mg m
3

Sr mg m
3

V mg m
3

Zn mg m
3

several reasons, including oxidant, igniter, crackling sound, or orange firedust generation. Bi2O3 is a safer substitute for Pb3O4 (Jennings-White, 1992); three fountains contained substantially more Bi (0.1e1%) than Pb (<50 ppm) while one contained 30 fold more Pb (9%) than Bi. Thus, the elimination of Pb from fireworks is not complete and considering the mean level in fountains, was actually higher than in a previous study of consumer fireworks (Alenfelt, 2000). The concentration of As, Be, Cd, Co, Se, Zr, were at or near analytical quantification limits (Table 2). Pyrotechnics were also analyzed with a field portable XRF (data not presented). The relatively high quantification limit of the XRF for some elements (100e1000 mg g
1; Co, Cr, Mn, Ni) limited the number of data pairs available for statistical analysis. One-way analysis of variance (ANOVA) of 14 paired samples showed a poor association between XRF and ICPMS data (Fe, Sr, and Zn, r2  0.10; Pb, r2 ¼ 0.31) implying that the XRF was an inadequate device for determining the metal content inside a consumer class pyrotechnic. The poor performance of the XRF in this application was likely a result of the heterogeneity of the pyrotechnic, shielding effects of cardboard packaging, and air voids. Selecting pyrotechnics which were homogeneous and were without packaging and air voids (dragon egg, flare, ribbon fuse, and sparkler) produced a much better correlation (r2 ¼ 0.99, p ¼ 0.003) for Sr, which was the only element to have more than two data pairs with values above quantification limits for this subset of devices.

8 200 100 <8

G. Croteau et al. / Atmospheric Environment 44 (2010) 3295e3303

Event

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G. Croteau et al. / Atmospheric Environment 44 (2010) 3295e3303

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Table 4 Gas and Vapor Exposure Monitoring Results (ppm, except PAHs, mg m
3). CH3CHOb

R-CHOc

PAHsd

CO

NO2

SO2

<0.02 <0.02 <0.02

< 0.02 < 0.02 < 0.02

e <0.02 <0.03 <0.03

e e <0.1e <0.1e

2 2 0 10

e e 0 0

e e 1.7 0.4

0.01 <0.008 <0.002

0.02 0.02 0.003

0.02 0.02 0.002

<0.005 <0.005 <0.002

e e e

e e e

e e e

e e e

500 750

e 0.3f

e 25f

20g 0.1h

l e

25 75

3 5

e 0.25

Event

Sample

Period

Acetone

1

Personal A, Finale Personal B, Finale Area, Penultimate Act Area, Finale

18 6 4 4

e <0.06 <0.09 <0.09

Personal, Finale Area B, Finale Area C, Entire show

27 23 76

2

ACGIH 8-h TLV (ppm) ACGIH STEL TLV (ppm)

HCHOa

benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene. benzo(ghi)perylene. ACGIH notation for PAHs: exposure by all routes should be carefully controlled to levels as low as possible. a Formaldehyde. b Acetaldehyde. c Acrolein, benzaldehyde, butylaldehyde, propionaldehyde. d Naphthalene, acenaphthylene, fluorene, acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene. e Quantification limit for naphthalene was 0.6 mg m
3. f ACGIH ceiling limit. g Propionaldehyde; no 8-h TLV exists for the other aldehdyes. h Acrolein 0.1 ppm ceiling limit.

non-combusted material was a combination of exterior packaging and fiberboard tubes that contained the pyrotechnic charge. Dragon eggs and ribbon fuse not having packaging had no residue. The emission factors developed for each device were subsequently based on the combusted mass. All of the devices tested generated a considerable amount of airborne particulate matter ranging from 7 to 14% of the combusted mass (Table 6). Potassium, the metal with the highest emission factor for all of the devices, comprised a large fraction of the total airborne particulate matter (25e41%), suggesting the prevalent use of potassium salts as oxidizers. Assuming that KNO3 was the primary oxidizer, the emission of Mg and Al, presumably as oxides, amount to only 3e6% of stoichiometric oxidizer consumption, leaving the balance for oxidation of carbon and sulfur in black powder. Primary colorants, Ba, Cu, and Sr, varied considerably between devices, an apparent reflection of the different color schemes evolved during combustion. Gallium is not a known component of fireworks devices; its emission rate was highly correlated with that of Pb (r2 ¼ 0.93, p ¼ 0.0003) but not with two metals associated with its production (Al and Zn). Very high lead emission factors (1.6 and 2.7% of the total combusted mass) were noted for two of the devices, with the remaining five devices having lead emission factors less than 0.01% of the combusted mass. The large amount of lead released from dragon eggs and ribbon fuse not only poses a certain human health hazard through the respiratory and oral exposure routes, but would also be an environmental contaminant post deposition. The high emission

factors for Ba, Cu, and Zn also present a potential human health and environmental hazard. The emission factors for Cr6þ, Ni, As, Cd, and Co, metals known to cause serious health effects at low exposure levels, were less than 5 mg kg
1 (Supplementary information, Table A1). The potential of a grab sample analysis to predict emission factors from pyrotechnics was assessed by ANOVA (Supplementary information, Table A2). Bi, Cr, Mg, Pb, and Sb had a very high and statistically significant (p < 0.05) correlation (r2 ¼ 0.89, 0.91, 0.84, 0.99, 0.97, respectively) between the metal concentrations in samples from a device and their emission factor. However, several other metals (Ba, Fe, Mn, Sr, and Zn) had a poor association (r2 ¼ 0.12, 0.08, 0.25, 0.02, 0.17, respectively) between metal concentration and emission factor. The variable results of this analysis could be a result of heterogeneity (observed later after sectioning vertically) within a pyrotechnic component. Additionally, the small sample size (n ¼ 7) and three to four order of magnitude differences in metal concentrations between the pyrotechnic devices further limits the applicability of this association. Each of the devices tested generated a considerable amount of sulfate, most of which was found as the salt and not the acid (Table 7). Most of the sulfate was likely generated by the oxidation of elemental sulfur from black powder during combustion, although a small amount of sulfate may also have originated from metal salts such as CuSO4 or Sb2S3. Elemental sulfur, along with charcoal and KNO3 comprise black powder, a primary ingredient in most pyrotechnics. Considerable variation in the amount of sulfate generated

Table 5 Aspects of Pyrotechnics used for Emission Factor Determination. Description

Dragon Eggs 5 pieces

Ribbon fuse6 m long

Roman Candle B 10 shots

Fountain Aa 7 chambers

Fountain Ba 3 chambers

Fountain C 1 chamber

Fountain D 1 chamber

Burn Time s

23.0

35.4

35.6

151.3

84.6

50.9

38.8

Mass Balance

g

%

g

%

g

%

g

%

g

%

g

%

g

%

Initial Mass Non-combusted residue Particulate matter - Deposited - Airborne Gasses Unaccounted emissions

10.8 0.0 3.1 1.6 1.5 0.04 7.7

100.0 0.0 28.5 14.8 13.7 0.4 71.1

172.2 0.0 55.3 33.2 22.1 0.04 116.8

100.0 0.0 32.1 19.3 12.9 <0.1 67.8

65.5 46.3 6.9 5.3 1.7 0.1 12.2

100.0 70.7 10.6 8.0 2.5 0.2 18.6

1018.2 630.7 132.1 106.1 26.0 1.0 254.5

100.0 61.9 13.0 10.4 2.6 0.1 25.0

1128.3 968.6 73.4 58.4 14.9 1.1 85.2

100.0 85.8 6.5 5.2 1.3 0.1 7.6

156.3 97.4 25.8 20.7 5.1 0.01 33.1

100.0 62.3 16.5 13.2 3.3 <0.1 21.2

78.9 43.5 14.0 11.1 2.9 0.02 21.4

100.0 55.1 17.7 14.1 3.6 <0.1 27.1

a

Mean of duplicate test events.

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G. Croteau et al. / Atmospheric Environment 44 (2010) 3295e3303

Table 6 Total Particulate matter and Metal Emission Factorsa (mg emitted/kg combusted device). Analyte d

TP K Mg Ba Na Ca Cu Al Pb Ga Sr Zn Fe Bi P Mn Ti Cr Sn Si Cr6þ Rb Sb V Te

Dragon Eggs

Ribbon Fuseb

Roman Candle B

Fountain Ac

FountainBc

Fountain C

Fountain D

140,000 34,000 6800 3000 < 380 51 7900 1900 16,000 680 15 75 120 0.6 53 19 11 120 15 <190 12 8.8 5.3 <0.4 7.0

130,000 45,000 2100 6300 57 22 3000 1000 27,000 1400 10 630 100 3.7 11 37 4.1 <1.7 0.6 <24 na 6.7 0.5 <1.7 <0.7

86,000 33,000 1300 30 < 210 33 4600 760 10 6.8 8.5 32 560 540 20 10 17 <6.4 6.5 <110 7.1 3.7 1.4 <6.4 <2.2

67,000 23,000 3400 49 130 210 2400 1500 2.0 4.8 190 400 50 310 12 31 59 6.9 20 4.0 0.2 3.8 0.8 6.9 <0.1

94,000 35,000 3400 120 1200 160 1900 1500 3.9 14 150 79 63 15 17 27 71 47 14 <13 0.6 6.4 0.5 47 <0.3

87,000 36,000 2500 310 850 41 200 1300 3.3 71 30 24 51 0.3 13 26 9.1 3.9 0.2 47 na 4.5 0.1 3.9 <0.7

81,000 33,000 2400 1400 < 120 690 45 850 120 320 710 120 42 < 0.1 23 39 2.8 <3.5 1.7 350 na 3.3 0.6 <3.5 <1.2

na e Not analyzed. a Metals for which the emission rate was greater than 5 mg kg
1 (See Supplementary information, Table A1 for other metal emission factors). b Mean of four replicate samples collected during a single test event; mean CV ¼ 11%. c Mean of duplicate test events; Fountain A mean CV ¼ 46%; Fountain B mean CV ¼ 23%. d Total airborne particulate matter.

by the four devices was noted, with dragon eggs generating more than four times as much airborne sulfate as Fountain A. A strong association was observed between the mass of SO2
4 and potassium generated during combustion (r2 ¼ 0.87, n ¼ 6; mean K:S ¼ 5.73), suggesting that most of the sulfate likely originated from elemental sulfur and differences in the SO2
4 emission factors resulted from variations in the black powder content between the tested devices. Dutcher et al. (1999) found a K:S ratio of 2.76 in ambient air samples taken during July 4th celebrations, similar to K:S ratio of 2.75 in black powder. The devices also generated a large amount of chloride ion, again primarily in the salt as opposed to acid form. Chlorine is present in pyrotechnic devices as a colorant (BaCl2, CuCl2, NaCl), oxidant (ClO
4 ) and chloroorganic color enhancers. Chlorine promotes the formation of alkaline earth metal halides, which produce brighter and more vivid colors than non-halogenated metal salts (Steinhauser and Klapotke, 2008). The small quantity of fluoride and absence bromine in combustion products indicate the reliance on chlorine as a halogen donor for color enhancement, an

Table 7 Inorganic Ion Emission Factors (mg generated/kg combusted device). Ion

Form

Dragon Eggs

Roman Candle B

Fountain Aa

Fountain Ba

SO2
4

Salt Acid Salt Acid Salt Acid Salt Acid Salt Acid

34,000 <770 3400 <310 <150 <320 <380 <770 <380 <1200

28,000 1500 1500 <180 <86 <180 <210 <430 <210 <650

8000 110 4300 61 170 <9.0 <11 <21 <11 <32

19,000 120 3400 34 44 <22 <26 <52 <26 <78

Cl
F




PO3
4 Br


a Mean of duplicate test events; Fountain A mean CV ¼ 51%; Fountain B mean CV ¼ 50%.

observation consistent with the lack of any fluoro- or bromocompounds in pyrotechnic formulations (Shimizu, 2004). The high concentration of metals and other cations, relative to that of free hydrogen, appears to favor the generation of the salt form of SO2
4 , Cl
and F
, over that of the acid form. The combustion environment was monitored for inorganic
nitrogen species in both the particulate (NO
2 , NO3 ) and gaseous (NO, NO2) forms (Table 8) and with the notable omission of N2, account for the inorganic nitrogenous byproducts that would likely be generated. A relatively small quantity of these nitrogen oxides was generated, with the particulate phase forms (ionic) being favored over the gas phase. Nitric oxide was generated in small quantities (6 mg kg
1) in three of four devices and NO2 was only generated in a single device. However, the small quantity of NO and NO2 generated is relevant since both cause upper respiratory tract irritation at low levels (10 and 60 ppm, respectively) after a short exposure (ACGIH, 2001). The very low generation of measurable nitrogen species indicate that the large quantity of nitrate initially present in these devices, as both an oxidant (e.g. KNO3) and colorant (e.g. Ba(NO3)2), was predominately converted to N2 per the theoretical combustion of black powder (Steinhauser and Klapotke, 2008). These results are

Table 8 Nitrogen Species Emission Factors (mg generated/kg combusted device). Ion

Form

Dragon Eggs

Roman Candle B

Fountain Aa

Fountain Ba

NO
2

Salt Acid Salt Acid Gas Gas

<270 <390 <270 <390 <4.7 <2.2

1000 <220 <150 <220 5.3 <1.2

280 <11 280 37 1.2 <0.1

170 <26 1000 38 6.0 0.4

NO
3 NO NO2

a Mean of duplicate test events; Fountain A y mean CV ¼ 110%; Fountain B mean CV ¼ 69%.

G. Croteau et al. / Atmospheric Environment 44 (2010) 3295e3303

consistent with Drewnick et al. (2006) and Vecchi et al. (2008) who found no increase in the airborne nitrate concentration in ambient air samples collected before, during, or after an outdoor pyrotechnic display. The small quantity of NO and NO2 generated suggest that any oxygen released during combustion was quickly consumed by fuels in the pyrotechnics as the formation of these oxides is favored at high temperatures when N2 is in the presence of reactive oxygen species (Radojevic, 2003). The absence of any of the nitrogenous analytes being generated by the dragon eggs was caused by the lack of nitrates in their formulation. The formation of organic compounds during the combustion of pyrotechnics is a complex process, with a myriad of compounds potentially being generated. Factors influencing the formation of organic compounds are organic carbon content and extent of oxidation. Consequently, a device such as dragon eggs that has no cellulose based packaging and a minimal quantity of organic binder, generated just a few organic compounds (Supplementary information, Table A3) d a notable contrast to fountains A and B, which generated numerous compounds. Both of these fountains had a considerable amount of packaging along with the charges being contained in fiberboard tubes. These results are consistent with a study by Fleischer et al. (1999) that found the generation of dibenzo-p-dioxins and dibenzofurans was largely associated with the combustion of the cellulose packaging material for a given device, as opposed to the actual pyrotechnic charge. Carbonyls were generated by each device (Table 9). Benzaldehyde, the only aromatic aldehyde quantified, was not emitted, at levels greater than the limit of quantification, by any device. Acetaldehyde was produced by each device and with one exception had the highest emission factor. In reference, Andreae and Merlet (2001) found the following emission factors associated with biomass burning (mg of analyte kg biomass
1): formaldehyde, 350e2200; acetaldehyde, 500e650; acrolein, 80e240; propionaldehyde, 9e140; acetone, 435e555; benzaldehyde, 29e36. The lower carbonyl emission factors associated with pyrotechnics may be a result of their lower organic carbon content and enhanced combustion. Acrolein and formaldehyde generation are a health concern, as brief exposures to low concentrations (0.25 and 0.1 ppm, respectively) can cause respiratory irritation (ACGIH, 2001). Many PAHs are suspected or known carcinogens. Therefore, the ACGIH uses the phrase “exposure by all routes should be carefully controlled to levels as low as possible”, in place of an actual threshold limit value. PAHs generation was low; only five of the 17 PAHs quantified had an emission factor exceeding 5.0 mg kg
1 (Table 10; Supplementary information, Table A4). Generation of naphthalene and acenaphthylene was favored over more complex PAHs. Not unexpectedly, low molecular weight PAHs were largely in the vapor phase, (e.g. naphthalene, 94%; acenaphthylene, 73%), with higher molecular weight PAHs predominantly in the particulate phase.

3301

Many factors affect the generation of PAHs during combustion including carbonaceous substrate composition, temperature, oxygen concentration, and the presence of other compounds. The combustion of highly oxygenated substrates, such as carbohydrates, generate considerably less PAHs than less oxygenated compounds (Schmeltz and Hoffmann, 1976). Lab scale experiments have shown PAHs generation to be optimal at temperatures ranging from 700 to 850  C (McMahon and Tsoukalas, 1978) whereas light emitting firework temperatures are 1500e3000  C (Conkling, 2001). Anaerobic pyrolysis favors PAHs formation (McMahon and Tsoukalas, 1978), and nitrate has been shown to inhibit PAHs formation (Schmeltz and Hoffmann, 1976). The devices had a high nitrate composition, oxidizers, low carbon content which was largely carbohydrate, and burned at a high temperature. Thus, pyrotechnics would be expected to generate less PAHs than other carbonaceous substrates. However, the PAHs emission factors found in this study (naphthalene, 57e94 mg kg
1; acenaphthylene, 4e100 mg kg
1) were not consistently less than those of burning land clearing debris (naphthalene emission factor 7e18 mg kg
1; Lutes and Kariher, 1997; Jenkins et al., 1996), agricultural residue (naphthalene emission factor 5e196 mg kg
1; Jenkins et al., 1996) and household waste (naphthalene emission factor 7 mg kg
1; Lemieux, 1997). Reproducibility of the emission factor results was assessed by testing fountains A and B in duplicate and also by the simultaneous collection of quadruplicate air samples from the ribbon fuse burn. Four possible sources of variability in determining emission factors were device construction and contents, combustion, sample collection, and analysis. For the ribbon fuse samples collected in quadruplicate, the mean percent coefficient of variation (%CV) for metals was 11% (Table 6). In contrast, the %CV for fountains A and B resulting from duplicate burn tests was 46 and 23%, respectively (Table 6). Thus, greater variability was associated with device construction, combustion, or content than sample collection. The coefficient of variation for fountain A was consistently greater than that of fountain B for all analytes: metals (Table 6), inorganic ions (Table 7), nitrogen species (Table 8), carbonyls (Table 9), and PAHs (Table 10). This may be a result of fountain A being a more complex, seven chambered fountain as compared to the six chambered (with three being duplicates) fountain B. The %CV for metals analyses in samples was consistently lower than that of the other analytes (but not in laboratory QA/QC samples). One reason may be that the process of partial combustion of organic material is more complex than the conversion of metals into oxides. Emission factors alone cannot provide a quantitative measure of personal exposure. Actual exposures are dependent on many factors: the type and number of devices used, proximity of the individual to the source, dilution, and contaminant removal rate. Personal exposure levels can be estimated with an atmospheric dispersion models using emission factors and site specific variables such as topography and ground-level wind speed data for outside

Table 9 Carbonyl Emission Factors (mg generated/kg combusted device). Analyte

Dragon Eggs

Ribbon Fuse

Roman Candle B

Fountain Aa

Fountain Ba

Fountain C

Fountain D

Formaldehyde Acetaldehyde Acrolein Acetone Propionaldehyde Butyraldehyde Benzaldehyde

76 150 <15 <150 38 <0.1 <150

43 84 9.6 43 41 14 <24

8.6 43 <8.6 107 <8.6 <8.6 <86

52 67 1.9 26 21 6.6 <7.4

9.0 140 1.9 59 31 7.7 <26

<7.0 49 <7.0 <70 14 14 <70

82 210 12 140 70 12 <120

a

Mean of duplicate test events; Fountain A mean CV ¼ 74%; Fountain B mean CV ¼ 25%.

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G. Croteau et al. / Atmospheric Environment 44 (2010) 3295e3303

Table 10 PAH Emission Factors (mg generated/kg combusted device). Analyte

Dragon Eggs

Roman Candle B

Fountain Aa

Fountain Ba

Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene

<63 <120 <63 <12 5.7

79 100 <35 <5.4 3.9

57 4.0 1.7 0.6 3.5

94 7.6 <4.2 0.8 4.9

a Mean of duplicate test events; Fountain A mean CV ¼ 52.6%; Fountain B mean CV ¼ 14.4%.

sites and building layout and ventilation design data for indoor sites. The use of atmospheric dispersion models to estimate exposure levels is beyond the scope of this paper. However, the concentration of the airborne contaminants in the burn room can provide insight into relative health risks. Contaminant concentrations in the burn room were likely much greater than would be encountered in real life since airborne contaminants were confined to a relatively small volume without removal or dilution. Conversely, only one device at a time was tested in the study, whereas multiple devices would be consumed at a performance or celebration. The airborne concentration of each analyte, normalized to 400 g of combusted mass for each pyrotechnic, was compared to the 2009 ACGIH TLV. Fifteen analytes had an airborne concentration greater than 50% of their respective TLV (Supplementary information, Figure A1). The airborne concentration of several metals, relative to their TLVs, were exceptionally high, with Cu, Ba, and Pb being more than 100 times the TLV for at least one device. Airborne lead levels for devices 1 and 6 were 3200 and 5200 times the TLV. Although the potential metal exposures resulting from pyrotechnics are a concern, the intermittent, short-term nature of the exposure would limit the potential health effects. In contrast, shortterm exposure to NOx, H2SO4, formaldehyde and SO2 could induce respiratory irritation and other more serious respiratory effects.

4. Conclusions This study shows that ground-level pyrotechnics generate airborne contaminants at levels, which could be a health hazard. Individuals proximal to the pyrotechnics are especially at risk. SO2 exposure exceeded the threshold for bronchoconstriction in asthmatics based on personal air monitoring at two performances utilizing consumer pyrotechnics. Emission factors for seven pyrotechnics indicated that many metals, including barium, strontium, copper and lead, as well as known respiratory irritants, were at levels exceeding ACGIH occupational exposure guidelines. Elements (Sb and unalloyed Mg), which are banned from consumer fireworks, were present in significant amounts. Be which is extremely hazardous through inhalation has not previously been found in fireworks and should be quantified in any future work. These results indicate a need for exposure monitoring when performers, technicians and other workers are exposed to airborne contaminants from pyrotechnics. As a screening tool, pyrotechnic emission factors in conjunction with computer based dispersion models can be used to estimate exposure levels. Workers should be protected through respiratory protection equipment or increased ventilation when exposure levels approach the ACGIH TLV. A better alternative would be using pyrotechnics that generate lower amounts of hazardous contaminants. In addition, warnings specific to the potential airborne exposures should be provided to both the general audience at events where these pyrotechnics are used, as well as the point of sale for consumer (1.4 G) pyrotechnics.

A priority should be placed on using pyrotechnics that generate less airborne pollution. Although, the presence of Pb3O4 and other Pb compounds in consumer pyrotechnics are prohibited by the National Fire Protection Association (NFPA, 2006), some products contain lead, as shown by this study. The American Fireworks Standards Laboratory, an organization that analyzes fireworks for compliance with federal regulations, found that 7.1% of the 7.1 million devices tested were not in compliance with federal regulations (AFSL, 2006). Given the limited importance of lead to the overall function of pyrotechnics and moreover the adequate substitute of Bi3O4 for Pb3O4 for sound effects, no legitimate need exists for lead use in pyrotechnics. The use of high nitrogen containing compounds such as tetrazole, as a substitution for the traditional fuel/oxidant mixtures, such as black powder, can substantially reduce particle and gas generation (Steinhauser and Klapotke, 2008). By eliminating carbon, sulfur and metal-based fuel in a pyrotechnic, the generation of airborne particles, organic compounds, SO2 and CO would be greatly reduced. Furthermore, the resulting reduction in particle generation and enhanced visibility of the display, allows for a tenfold reduction in the amount of metals used as colorants. Less toxic substitutes for perchlorate and barium have also been developed (Damavarapu et al., in press; Klapotke et al., 2009; Steinhauser and Klapotke, 2010). Pyrotechnics designed to reduce airborne contaminant generation are currently being used in many indoor venues (Halford, 2008). The use of an airtight burn room proved to be an economical and effective method for determining the emission factor of pyrotechnics. This method is similar to that used for determining emission factors for burning household waste (Lemieux et al., 2000) and scrap tires (Lemieux and Ryan, 1993). However, these systems were dynamic, as oxygen must be provided for combustion, a condition unnecessary for pyrotechnics. Acknowledgements The authors acknowledge the performers and technicians of Cirque de Flambé for their willingness to participate in the study. Analytical work by the University of Washington Environmental Health Laboratory staff was greatly appreciated. We acknowledge support from the Medical Aid and Accident Fund of the State of Washington, Department of Labor and Industries. We thank the City of Renton Fire Department for use of their facility. Appendix. Supplementary information Supplementary data associated with this article can be found in the online version at doi:10.1016/j.atmosenv.2010.05.048. References Alenfelt, P., 2000. Chemical analysis of consumer fireworks. Journal of Pyrotechnics 11, 11e15. American Congress of Governmental Industrial Hygienists (ACGIH), 2001. Documentation of the Threshold Limit Values and Biological Exposure Indices, seventh ed. ACGIH, Cincinnati, OH. American Fireworks Standards Laboratory (AFSL), 2006. Testing Results. www.afsl. org/Testing_Results.htm. American Congress of Governmental Industrial Hygienists (ACGIH), 2009. Threshold Limit Values and Biological Exposure Indices. ACGIH, Cincinnati, OH. American Pyrotechnics Association (APA), 2007. U.S. Fireworks Consumption Figures 2000e2008. www.americanpyro.com/press/facts/FireworksConsumption Figures.pdf. Andreae, M.O., Merlet, P., 2001. Emissions of trace gases and aerosols from biomass burning. Global Biogeochemical Cycles 15, 955e966. Attri, A.K., Kumar, U., Jain, V.K., 2001. Microclimate - formation of ozone by fireworks. Nature 411, pp. 1015. Becker, J.M., Iskandrian, S., Conkling, J., 2000. Fatal and near-fatal asthma in children exposed to fireworks. Annals of Allergy Asthma & Immunology 85, 512e513.

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