Emission Characteristics of Polycyclic Aromatic Hydrocarbons from Asphalt Concrete Manufacturing Facilities in South Korea

Abstract

Asphalt concrete (ascon) manufacturing facilities in South Korea are located near urban areas and emit various air pollutants, including polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (BaP), a Group 1 carcinogen. However, few measurement-based studies exist in Korea, and no domestic BaP emission factor has been established, making its effective management difficult. In this study, PAH concentrations emitted from stacks were measured using gas chromatography/mass spectrometry at 29 facilities located near densely populated areas. BaP was detected at all facilities, and emission factors were calculated based on the ascon materials and dryer fuel types. The calculated emission factors were found to be 31 to 6230 times higher than the AP-42 standards provided by the US Environmental Protection Agency. This discrepancy likely arises from differences between processes and fuel characteristics. Using the California Puff model, BaP concentrations in the near area were predicted, corresponding to as much as 30% of the US National Ambient Air Quality Standards. These findings indicate a potentially significant environmental health risk in nearby communities. The findings of this study can serve as foundational data for formulating policies and providing institutional support aimed at managing emissions from ascon manufacturing facilities in Korea.

1. Introduction

Asphalt concrete (ascon), a mixture of asphalt (obtained by refining crude oil through atmospheric pressure and vacuum distillation) and aggregate (e.g., gravel and sand) or pavement fillers (crushed rock and fillers), is mainly used for road and parking lot pavements [1,2]. Ascon is generally produced at temperatures of 160 °C or higher and must be transported within 2 h at high temperatures to prevent hardening [3,4,5]. For this reason, most ascon manufacturing facilities are located in air-quality management areas near urban regions [6]. The ascon production process generates substantial amounts of air pollutants, including CO₂, CO, NO_x, SO₂, volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs) [1,7,8]. Drying facilities, in particular, emit a significant amount of particulate matter (PM). Ascon production peaks during early morning hours with lower vehicle traffic, and air pollutant emissions fluctuate owing to irregular operating hours and days [6,9].

Raw materials constituting asphalt contain several harmful substances, such as PAHs and VOCs; consequently, workers handling ascon and residents in nearby areas are exposed to certain carcinogens [10,11,12]. Bal et al. [13] reported that exposure to PAHs from asphalt fumes generated during road paving may cause germline DNA mutations. Oliveira et al. [14] confirmed that exposure to high concentrations of PAHs in urban areas causes toxicity in children and elderly individuals. Jung et al. [15] reported that direct skin exposure to benzo(a)pyrene (BaP), a class 1 carcinogen according to the International Agency for Research on Cancer (IARC), inhibits melanin production in cells and contributes to skin diseases such as vitiligo. Therefore, identifying the emission characteristics of PAHs from ascon manufacturing facilities is essential for protecting the health of residents in nearby urban areas. However, few studies have reported the emission characteristics and environmental impacts of PAHs from ascon manufacturing facilities in Korea.

Currently, emissions of air pollutants (PM, SO₂, and NO₂) from ascon manufacturing facilities in Korea are calculated using the emission factors (AP-42) provided by the US Environmental Protection Agency (US EPA) [6,16]. However, emissions calculated using such overseas data have limitations in accurately reflecting domestic emission sources. In particular, pollutant emissions at individual facilities may differ significantly from measured emissions when overseas emission factors are applied [17]. Moreover, emission factors for PAHs, including highly toxic carcinogens such as BaP, have not yet been calculated specifically in Korea. Thus, effective management of hazardous air pollutants from ascon facilities necessitates the replacement of overseas emission factors through the development of emission factors specific to Korean ascon manufacturing facilities and the calculation of accurate emission rates.

This study investigated the emission characteristics of PAHs from ascon manufacturing facilities in Korea. Among 515 ascon manufacturing facilities nationwide, 29 located less than 1 km from residential areas in densely populated administrative districts were selected. PAH concentrations emitted from the stacks of these selected facilities were measured. Specifically, an emission factor was calculated for BaP, a class 1 carcinogen recognized by IARC. Additionally, the California Puff (CALPUFF) atmospheric dispersion model was used to evaluate atmospheric concentrations and exposure levels of BaP. The results of this study indicate the need to develop emission factors reflecting the unique characteristics of ascon manufacturing facilities in Korea. These findings are expected to serve as fundamental data for accurately calculating harmful air pollutant emissions, assessing their environmental impacts, and establishing risk-based management policies.

2. Materials and Methods

2.1. Ascon Manufacturing Facilities

As of 2019, 515 ascon manufacturing facilities were in operation in Korea, as shown in Figure 1. Among these, 29 facilities located within 1 km of residential areas in densely populated administrative districts with high air pollutant emissions were selected. These included seven facilities producing recycled ascon and 22 producing general ascon. The ascon manufacturing processes were subdivided according to the type of dryer fuel—bunker C oil (BCO), liquefied natural gas (LNG), liquefied petroleum gas (LPG), and vacuum distillation oil (VDO)—and data for each facility were collected (

Table 1. Sampling status of 29 selected ascon manufacturing facilities.

Ascon Production Type		Number
Recycled ascon	LNG	3
	LPG	3
	BCO	1
General ascon	LNG	7
	LPG	3
	BCO	10
	VDO	2

).

2.2. Sample Collection and Analysis

PAHs have a wide range of vapor pressures and exist in both gaseous and particulate phases in the atmosphere at pressures of approximately 10⁻⁸ kPa or higher. Therefore, gaseous and particulate samples emitted from the stacks of the ascon manufacturing facilities were collected through isokinetic sampling using an adsorbent (XAD-2, Supelco, Bellefonte, PA, USA) and a filter (thimble filter, Toyo Roshi Kaisha Ltd., Chiyoda-ku, Tokyo, Japan) [18]. After sample collection, 100 µL of surrogate standard (10 µg/mL) was injected, and extraction was performed for 15 min at 150 °C using an accelerated solvent extraction system (ASE 200E, Dionex Corp., Sunnyvale, CA, USA). Hexane and acetone (9:1) were used as extraction solvents. The samples were concentrated using a rotary evaporator (Heidolph, Schwabach, Germany) and an automatic concentration system (Turbovap, Zymark, Watertown, MA, USA). The concentrated samples were further concentrated to a final volume of 1 mL under high-purity nitrogen after removing moisture through a column containing anhydrous sodium sulfate.

Gas chromatography/mass spectrometry (GC/MS, Agilent HP-6890/5973N, Agilent technologies, Santa Clara, CA, USA) was used for compound identification and quantification, following the U.S. EPA Method TO-13A and the Korean Official Test Method for Air Pollution (ES 01552.1). To ensure analytical reliability, quality control/quality assurance (QC/QA) was conducted using PAH standards (AccuStandard Inc., New Haven, CT, USA), surrogate standards (SS), and internal standards (IS). Calibration was performed using 5–6 concentration points in the range of 0.5–2 ng, yielding calibration curves with high linearity (R² > 0.98) for most compounds. Retention time reproducibility across 7 injections showed relative standard deviations (RSDs) below 0.1%. Method detection limits (MDLs) were calculated based on replicate analyses of low-concentration standards, applying t-values at the 99% confidence level. For BaP, the MDL was 0.02 ng/µL, corresponding to approximately 0.003 ng/m³ after considering a standard air sampling volume of 7200 L. Surrogate recovery was evaluated for each sample to correct for losses during pretreatment. Six surrogate standards were used: naphthalene-d8, acenaphthene-d10, phenanthrene-d10, chrysene-d12, perylene-d12, and dibutyl phthalate-d4. The average recoveries for particle-phase samples fell within the acceptable recovery range (60–120%) recommended by US EPA Method 8100. The final PAH concentrations were corrected based on the recovery rates of the surrogate standards.

Table 2. Analyzed PAH compounds.

No.	Compounds	No.	Compounds
1	Naphthalene	17	Benzo(j,k)fluoranthene
2	Biphenyl	18	Benzo(a)fluoranthene
3	Acenaphthylene	19	Benzo(e)pyrene
4	Acenaphthene	20	Benzo(a)pyrene
5	Fluorene	21	Perylene
6	Dibenzothiophene	22	Dibenz(a,h)anthracene
7	Phenanthrene	23	Indeno(1,2,3-cd)pyrene
8	Anthracene	24	Dibenz(a,c)anthracene
9	4H-Cyclopenta(def)phenanthrene	25	Benzo(b)chrysene
10	Fluoranthene	26	Dibenz(a,j)anthracene
11	Pyrene	27	Benzo(ghi)perylene
12	Benzo(c)phenanthrene	28	Anthanthrene
13	Benz(a)anthracene	29	Picene
14	Chrysene	30	Coronene
15	Triphenylene	31	Dibenzo(a,e)pyrene
16	Benzo(b)fluoranthene	32	Dibenzo(b,k)fluoranthene

and

Table 3. GC/MS conditions for PAH analysis.

Parameter	Condition
Detector	MS (Agilent 5973N, Agilent technologies, Santa Clara, CA, USA)
Column	J&W HP-5 (30 m × 0.32 mm× 0.25 µm)
Column flow	1.5 mL/min
Auto Injector	G4513A
Purge flow	He (99.999%), 15.0 mL/min
Inlet temperature	280 °C
GC temperature program	60 °C (5 min) → 10 °C/min → 200 °C (5 min) → 10 °C/min → 200 °C (5 min) → 310 °C (10 min) → 320 °C (5 min)

present the 32 analyzed PAH compounds and the GC/MS analysis conditions, respectively.

2.3. Estimation of Emission Factor

This study aims to present emission factors derived from measurement data to calculate BaP emissions from ascon manufacturing facilities in Korea. The emission factor was calculated using Equation (1) [6].

$$Emission factor \left(\mathrm{kg}/\mathrm{ton}\right)={\displaystyle \frac{BaP concentration \left(\mu \mathrm{g}/{\mathrm{m}}^3\right)\times Dry emission flow rate \left({\mathrm{m}}^3/\min \right)\times {10}^{-9}}{Production Volume \left(\mathrm{ton}/\min \right)}}$$

(1)

Owing to irregular operating hours and days resulting from varying production schedules, pollutant emissions from ascon manufacturing facilities fluctuate significantly. Therefore, calculating emission factors based on daily flow rates is inappropriate. Therefore, the emission factors in this study were calculated based on gas flow rates per minute to minimize variability.

2.4. CALPUFF Model

The CALPUFF model used in this study is a Lagrangian–Gaussian puff model adopted by the US EPA. It is an unsteady-state model capable of considering temporal and spatial variations in wind fields for puff transport, assuming that emissions continuously discharged from a stack are released as discretized puffs [19,20,21]. CALPUFF calculates temporal concentration changes for both point and area sources and enables modeling over complex terrains and distances up to hundreds of kilometers from pollutant sources, providing hourly, daily, and yearly concentration predictions [22,23].

The CALPUFF modeling system comprises three components: CALMET, CALPUFF, and CALPOST [24,25]. CALMET is a meteorological model that generates three-dimensional meteorological fields from weather data and geographic parameters. It includes preprocessing modules: TERREL, CTGPROC, and MAKEGEO (for terrain and land cover map input), SMERGE (surface weather observation data preprocessing), and READ62 (upper-air meteorological data preprocessing). CALMET results feed into CALPUFF to simulate the transport, transformation, and removal of pollutants influenced by varying meteorological conditions. Finally, CALPOST processes the CALPUFF output data, summarizing simulation results in tabular or gridded formats.

The facilities selected for CALPUFF modeling were classified according to land use among 29 facilities to compare dispersion characteristics of BaP emissions under different atmospheric and geographic conditions. Three representative facilities located in urban areas and three in suburban areas were selected. For terrain inputs in the CALPUFF model, land cover maps from the Korean Ministry of Environment were utilized, and terrain elevation data were obtained from SRTM3 (~90 m) provided by the United States Geological Survey. Meteorological input data, including temperature, wind speed, wind direction, air pressure, cloud height, and precipitation, were hourly measurements from weather stations located in the areas of the 6 selected facilities. Stack parameters, including stack height, diameter, temperature, and flow rate, were obtained from site investigations. BaP emissions for each facility were calculated using measured BaP concentrations and stack specifications, and dispersion modeling was performed with the CALPUFF model. The modeling domain was composed of 2500 grid cells (50 × 50) centered on each facility.

3. Results and Discussion

3.1. Emission Characteristics of PAHs

Figure 2 shows the emission concentrations of 18 PAHs detected in the chimneys of 29 ascon manufacturing facilities. Among the PAHs, naphthalene exhibited the highest concentration, followed by acenaphthylene, benzo(e)pyrene, fluorene, phenanthrene, and BaP. These substances have been frequently identified in various studies related to ascon manufacturing processes [26,27,28,29]. Owing to their strong toxicity and persistence, these PAHs are highly harmful to human health and ecosystems. Notably, BaP, a class 1 carcinogen according to IARC, was detected at all 29 facilities. The average emission concentration of BaP was 1.78 µg/m³, which is approximately 1/28 of the emission standard of 50 µg/m³. However, this level is relatively high compared to emission concentrations (≤1 µg/m³) reported for other industries, such as coal liquefaction, coal-tar distillation, wood impregnation, and power plants [30]. Given the high risk associated with BaP, proper management measures are required, based on accurately characterizing BaP emissions from ascon manufacturing facilities in Korea.

Ascon manufacturing facilities in Korea typically use an integrated batch process consisting of storage, drying, sorting, measuring, and mixing stages. Thus, exhaust gases generated during each stage are collectively treated via pollution-control facilities and discharged through stacks. Among these processes, the drying stage is a primary emission source, producing substantial amounts of PAHs as asphalt and other organic materials evaporate and decompose under high-temperature conditions [31]. The type of fuel used in the drying process can significantly influence emission characteristics, as the pollutants generated during combustion vary in type and concentration depending on fuel type. Additionally, emissions may differ when recycled ascon is produced by incorporating waste ascon to conserve resources and reduce costs.

Figure 3 shows PAH and BaP concentrations per ton of asphalt used in batch-type ascon manufacturing facilities. With the same amount of asphalt usage, the average PAH concentration was 1.60 × 10⁻⁴ µg/m³ when liquefied gas (LNG and LPG) was used as dryer fuel, compared to 3.86 × 10⁻⁴ µg/m³ when heavy oil (BCO and VDO) was used, indicating that the use of heavy oil resulted in a concentration approximately 2.4 times higher. The average BaP concentration was approximately 2.21 × 10⁻⁸ µg/m³ when liquefied gas was used, versus approximately 8.39 × 10⁻⁸ µg/m³ when heavy oil was employed. These results confirm that the dryer fuel type significantly affects PAH and BaP emission characteristics in ascon manufacturing facilities.

Figure 4 shows the average concentrations of total PAHs and BaP according to dryer fuel type in recycled and general ascon manufacturing facilities. Regardless of the ascon material or dryer fuel type, the average particle-phase concentration ratio for total PAHs and BaP was less than 10%. This low ratio results from significant removal of condensed particulate PAHs by dust-control equipment as exhaust gases cool. For recycled ascon, BCO exhibited the highest total PAHs and BaP concentrations, followed by LPG and LNG. For general ascon, BCO exhibited the highest total PAHs and BaP concentration, followed by VDO, LPG, and LNG, whereas BCO exhibited the highest total PAHs concentration, followed by VDO, LNG, and LPG. No significant differences were observed in emission concentrations of total PAHs and BaP based on ascon raw materials. Additionally, the order of emission concentration by fuel type was similar, except for VDO in general ascon facilities. These findings indicate that BaP emission characteristics at ascon manufacturing facilities are consistent regardless of the inclusion of waste ascon and that existing air pollution control systems can effectively control emissions.

Figure 5 shows the average concentrations of total PAHs and BaP by dryer fuel type based on the data presented in Figure 4. The dryer fuel type in ascon manufacturing facilities marginally influences emission concentrations of total PAHs and BaP. Specifically, the use of BCO resulted in the highest average concentrations. BCO has high viscosity and aromatic content, conditions favorable for incomplete combustion and the formation of PAH precursors. VDO, a high-viscosity and low-volatility fuel with significant aromatic content, is similarly prone to generating PAHs compared to LNG and LPG. Meanwhile, LNG and LPG, methane-based and simple alkane-based fuels, respectively, are relatively clean fuels that facilitate complete combustion, resulting in the lowest emissions of both substances with similar concentration values. This indicates that LNG and LPG contribute similarly to PAH and BaP emissions. In Figure 4, however, BaP concentration from general ascon facilities using LPG was marginally lower than from those using LNG. This discrepancy is likely due to the smaller number of samples for LPG facilities, which may have introduced statistical error into average concentration calculations. Additionally, complex factors such as dryer operating conditions, raw material characteristics, and equipment aging may also influence emissions. A more detailed investigation of these factors in ascon manufacturing facilities, considering diverse variables, is necessary.

3.2. Estimation of Emission Factors for BaP

The BaP emission factors per ton of ascon produced were calculated as presented in

Table 4. Emission factors of BaP from ascon manufacturing facilities (unit: kg/ton production).

Ascon Production Type	Minimum	Median	Mean	Maximum	Standard Deviation	Number
Recycled Ascon	4.45 × 10−9	2.59 × 10−7	3.14 × 10−7	6.63 × 10−7	2.42 × 10−7	7
General Ascon	5.34 × 10−9	2.63 × 10−7	3.03 × 10−7	8.78 × 10−7	1.97 × 10−7	22
LNG	4.45 × 10−9	2.73 × 10−7	2.51 × 10−7	4.53 × 10−7	1.36 × 10−7	10
LPG	5.34 × 10−9	1.78 × 10−7	2.79 × 10−7	6.63 × 10−7	2.91 × 10−7	6
BCO	8.97 × 10−8	2.51 × 10−7	3.26 × 10−7	8.78 × 10−7	2.08 × 10−7	11

and Figure 6. The average BaP emission factor for the seven recycled ascon production facilities was calculated to be 3.14 × 10⁻⁷ kg/ton (range: 4.45 × 10⁻⁹ to 6.63 × 10⁻⁷ kg/ton). For general ascon manufacturing facilities, the average BaP emission factor was 3.03 × 10⁻⁷ kg/ton (range: 5.34 × 10⁻⁹ to 8.78 × 10⁻⁷ kg/ton). With respect to fuel type, the average BaP emission factor was 2.51 × 10⁻⁷ kg/ton (range: 4.45 × 10⁻⁷ to 4.53 × 10⁻⁷ kg/ton) for facilities using LNG, 2.79 × 10⁻⁷ kg/ton (range: 5.34 × 10⁻⁹ to 6.63 × 10⁻⁷ kg/ton) for LPG facilities, and 3.26 × 10⁻⁷ kg/ton (range: 8.97 × 10⁻⁸ to 8.78 × 10⁻⁷ kg/ton) for facilities using BCO. As shown in Figure 6, BaP emission factors from general ascon production facilities were distributed within a relatively narrow range after excluding outliers, whereas recycled ascon production facilities exhibited a wider range. This variation likely results from the uniform quality of raw materials used for general ascon, whereas recycled ascon exhibits higher variability in emission factors owing to the degradation of waste ascon, nonuniform raw material, and relatively higher heating temperatures [32].

The BaP emission factors calculated in this study were at least 31 times higher for LNG and up to 6230 times higher for BCO compared to the US EPA emission factor (1.41 × 10⁻¹⁰ kg/ton) for batch hot mix asphalt plants. Lee et al. [33] reported a BaP emission factor of 5.6 × 10⁻⁸ kg/ton when heavy oil was used in a preheating boiler at an ascon manufacturing facility. This is relatively comparable to the average emission factor (3.26 × 10⁻⁷ kg/ton) calculated for BCO fuel in the present study, differing by a factor of approximately 5.8. According to the US EPA’s AP-42, Section 11.1, the emission factors for BaP are based on facilities using predominantly LPG or light oil (No. 2 fuel oil) as fuels during asphalt mixture production [34]. However, the facilities selected for this study used fuels in the following order: BCO (n = 11), LNG (n = 10), and LPG (n = 6). Consequently, differences in emission factors between this study and EPA’s AP-42 values appear attributable to differences in fuel characteristics. Studies have evaluated whether EPA emission factors are appropriately applicable to industrial characteristics and environmental conditions in various countries. Gibson et al. [35], comparing measured emission factors at UK sites with EPA-derived BaP emission estimates, indicated that EPA standards could lead to either overestimations or underestimations, as they do not comprehensively reflect all emission sources specific to UK asphalt plants.

BaP emissions were calculated according to raw material and dryer fuel type for all 515 ascon manufacturing facilities in Korea using the emission factors derived in this study; results are shown in

Table 5. Emission of BaP using emission factors calculated in this study (unit: kg/year).

Area	Number of Emission Sources (ea)	BaP	%
Seoul/Gyeonggi/Incheon	72	0.00203	25.4
Busan/Ulsan/Gyeongnam	77	0.00100	12.5
Daegu/Gyeongbuk	82	0.00096	12.0
Gwangju/Jeonnam	58	0.00104	13.0
Daejeon/Sejong/Chungnam	68	0.00109	13.6
Gangwon	55	0.00061	7.6
Chungbuk	39	0.00056	7.0
Jeonbuk	48	0.00048	6.0
Jeju	16	0.00022	2.8
Sum	515	0.00800	100.0

. Facilities located in the Seoul, Incheon, and Gyeonggi regions accounted for more than 25% of total BaP emissions, the highest among all areas. These regions comprise the Seoul metropolitan area, which accommodates over half of Korea’s total population. Hence, it is critical to promptly identify hazardous emissions from ascon manufacturing facilities and implement measures to protect public health and the environment in nearby communities. In other words, it is essential to develop emission factors for harmful air pollutants, such as BaP, reflecting the specific process characteristics of Korean ascon manufacturing facilities.

3.3. CALPUFF Modeling

CALPUFF dispersion modeling was performed using stack specification information and measured BaP concentrations from the ascon manufacturing facilities, and the average dispersion concentration of the facilities was analyzed. The facilities selected for modeling were classified according to surrounding land use. As presented in

Table 6. BaP concentration and emission from ascon facilities.

Ascon Facility	Stack Specifications				BaP Concentration (ng/m3)	BaP Emission * (g/s)
	Exhaust Gas Quantity (m3/min)	Temperature (°C)	Stack Diameter (m)	Stack Height (m)
A	222.4	109.0	1.40	10	2071	7.67 × 10−6
B	395.3	61.3	1.10	12	1754	1.16 × 10−5
C	398.0	95.8	1.50	20	1401	8.64 × 10−6
D	513.2	99.1	1.40	13	1422	1.22 × 10−5
E	255.2	62.0	1.44	18	1829	7.78 × 10−6
F	100.5	82.0	1.45	15	1776	2.97 × 10−6

* Equation (2): BaP emission (g/s) = BaP concentration (ng/m³) × exhaust gas quantity (m³/min).

, three representative facilities located in urban areas (A, B, and C) and three in suburban areas (D, E, and F) were selected.

Figure 7 and

Table 7. Modeling results of BaP concentrations in ascon facilities.

Ascon Company	BaP Concentration Within 500 m Radius (ng/m3)	BaP Concentration Between 500 and 1000 m Radius (ng/m3)
A	0.370	0.073
B	0.488	0.192
C	0.209	0.074
D	0.218	0.142
E	0.407	0.156
F	0.361	0.072

show the results from CALPUFF dispersion modeling of BaP in areas surrounding these six ascon manufacturing facilities. Within a radius of 500 m from the facilities, BaP concentrations ranged from 0.209 to 0.488 ng/m³, with an average concentration of 0.342 ng/m³. Within a radius between 500 and 1000 m, BaP concentrations ranged from 0.072 to 0.192 ng/m³, with an average concentration of 0.118 ng/m³. These estimated concentrations are approximately 10–30% of the annual average concentration limit for BaP (1.0 ng/m³) set by the US National Ambient Air Quality Standard. This indicates the relatively significant contribution of BaP emissions from the ascon manufacturing facilities targeted in this study to their surrounding environments.

In both urban and suburban areas, BaP concentrations showed a clear tendency to decrease as the distance from emission sources increased. For facility A, located in an urban area, atmospheric turbulence was significant, and vertical dispersion was enhanced owing to densely situated buildings. Consequently, pollutant plumes dispersed rapidly upwards and diluted, causing concentrations to quickly approach background levels beyond 500 m. For facility E, situated in a suburban area with similar emission levels as facility A, pollutants traveled farther horizontally owing to open terrain and relatively low turbulence. Thus, BaP emitted from urban facilities exhibited localized high concentrations but rapidly diminished over short distances, while suburban emission sources maintained influence over moderate distances after forming initial high concentrations nearby. These findings indicate that differences in atmospheric dispersion conditions between urban and suburban environments significantly affect the spatial distribution of BaP.

However, the CALPUFF model results are subject to inherent limitations arising from uncertainties in input parameters, including emission rates, stack configurations, and meteorological data. The model assumes continuous emissions and excludes short-term operational variability and background sources such as traffic and residential heating. Consequently, BaP concentrations may be underestimated. Future work should aim to reduce these uncertainties through high-resolution emission inventories, time-resolved measurements, and validation against ambient monitoring data.

In Korea, BaP is designated as a “hazardous air pollutant” under the Clean Air Conservation Act; however, specific air quality standards for BaP have not yet been established. Therefore, stricter environmental protection standards, including regulatory measures and monitoring protocols for BaP emissions, are necessary. Particularly, standards reflecting domestic industrial characteristics and environmental conditions should be established for ascon manufacturing facilities, as these are significant sources of BaP emissions.

4. Conclusions

This study investigated the emission characteristics of PAHs from ascon manufacturing facilities in South Korea, focusing on BaP, a PAH known for its high human toxicity. Additionally, emission factors for BaP were calculated. The impact of potential exposure to BaP emitted from these facilities was quantitatively evaluated using CALPUFF atmospheric dispersion modeling. Based on these objectives, the following conclusions were drawn:

• Measurements at 29 facilities located near residential areas revealed that BaP was consistently detectable, underscoring the pollutant’s environmental and public health relevance.
• Dryer fuel type was a dominant factor influencing BaP emission levels. Facilities using heavy oils with high aromatic content (BCO and VDO) emitted significantly higher concentrations of BaP than those using cleaner fuels (LNG and LPG).
• The calculated BaP emission factors were up to 6230 times greater than the standard values in the US EPA’s AP-42, indicating that existing international emission factors do not accurately reflect the specific processes and fuel-use characteristics of domestic manufacturing facilities.
• Dispersion modeling showed elevated BaP concentrations within a 1 km radius of the facilities, with differing dispersion patterns in urban versus suburban areas.

These findings suggest a strong need to establish national emission factor guidelines to better reflect local fuel usage and operational practices. This study can serve as foundational data for assessing the current emission status of hazardous air pollutants from the domestic ascon industry and for establishing evidence-based policies to protect the health of nearby residents.