Emission Characteristics of Regulated and Unregulated Air Pollutants from Heavy Duty Diesel Trucks and Buses

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The emission characteristics of mobile air pollution sources belonging to the non-road sector have yet to be thoroughly investigated, especially when compared to those of on-road vehicles. Hence, the present study employed an engine dynamometer to evaluate the emissions of a diesel engine complying with Tier 3 standards during various driving modes (KC1-8, NRSC, and NRTC) and a portable emissions measurement system (PEMS) to assess those of two excavators, one complying with Tier 3 and the other with Tier 4 standards, during real-world working and driving conditions. The characteristics and chemical composition of the emitted regulated pollutants (carbon monoxide (CO), non-methane hydrocarbon (NMHC), nitrogen oxide (NO x), and particulate matter (PM)) and hazardous air pollutants (HAPs), e.g., volatile organic compounds (VOCs), aldehydes, and polycyclic aromatic hydrocarbons (PAHs), were then determined. For the regulated pollutants, NRTC mode generated the highest emissions owing to the rapid changes in engine load and speed during transitions. As a result of the after-treatment systems, which utilized a diesel oxidation catalyst (DOC) and selective catalytic reduction (SCR), CO, NMHC, and NO x emissions from the Tier 4-compliant excavator were lower than those from the Tier 3compliant diesel engine and excavator. The operating conditions of the diesel engine and construction equipment as well as the after-treatment systems significantly affected the composition of the non-methane volatile organic compound (NMVOC) emissions, which were dominated by alkanes that comprised 23 detected species. Sampling the particle-phase PAHs, we found phenanthrene, fluoranthene, and naphthalene; furthermore, we estimated the concentrations of the gas-phase PAHs with models to obtain the total PAH concentrations. Formaldehyde, which contributed the largest fraction of the aldehydes, was more abundant than the other species. Thus, emissions from non-road sources, including construction equipment, must be controlled because of the considerable health risks from pollutants such as formaldehyde and benzene. Our results will aid in the establishment of a national emission inventory for HAPs.

Section: Emission Characteristics Of Regulated Pollutantsmentioning

confidence: 78%

Section: Emission Characteristics Of Regulated Pollutantsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Emission Characteristics of Hazardous Air Pollutants from Construction Equipment

Jung

Kim

Lim

et al. 2020

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“…Many researchers (Lim et al, 2015;Tan et al, 2017;Zhang et al, 2018;Jung et al, 2019; Zhou et al, 2019) studied on characterizing PAHs and aliphatic compounds in DEPs. Diesel engines generate 100-320 nm particle size of PAHs under creep and idle driving conditions (Riddle et al, 2007).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Characterizations of Size-segregated Ultrafine Particles in Diesel Exhaust

Lim

Jung

2021

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Size-segregated ultrafine particles (UFPs) in diesel exhaust were investigated to characterize carbonaceous substances, metals, and organic compounds originating from a medium-duty diesel engine dynamometer using the 13 driving mode. Organic carbon (OC) and elemental carbon (EC) peaked at 330-550 nm, but the OC/EC ratio showed two peaks in the ultrafine and accumulation modes. The distribution trend of metal elements was opposite to that of the size-segregated OC/EC ratio. The amounts of toxic Pb, As, and Cd were less than 0.03-2.5% in diesel exhaust particles (DEPs), but their cumulative fractions in the ultrafine mode exceeded 50%. Most organic compounds (76.6%) and alkanes (67.0%) were emitted in the accumulation mode (170-1000 nm). More than 70% of the identified polycyclic aromatic hydrocarbons (PAHs) were emitted in the accumulation mode (94-1000 nm), with phenanthrene being the most abundant. Two significant size ranges of toxicity equivalent quantity peaks in the ultrafine (34-66 nm) and accumulation (170-330 nm) modes were observed for the size-segregated DEPs. Contrary to the trends for PAHs and organic compounds, the identifiable nitrogen-containing polycyclic aromatic compounds were more abundant in the ultrafine mode. Overall toxicity was high as UFPs can be deposited with high efficiency throughout the human respiratory tract.

“…S1(c)). Mobile sources such as heavy duty diesel trucks and buses could be important sources of volatile organic compounds (VOCs), aldehydes, and particulate matters (Yao et al, 2015;Jin et al, 2017;Rojas-Mendoza et al, 2017;Jung et al, 2019).…”

Section: Characteristics Of Air Toxic Emission In the Study Regionmentioning

confidence: 99%

Airborne Air Toxics Characteristics and Inhalation Health Risk Assessment of a Metropolitan Industrial Complex

Tsai

Chung

et al. 2019

Air toxics, also well-known as hazardous air pollutants (HAPs), have significant health effects on human health and are of great concern. This paper studied a number of hazardous air pollutants in an industrial and metropolitan complex area in order to determine their ambient abundance and potential health impacts. The target pollutants in this study are benzene, formaldehyde, 1,3-butadiene, arsenic, 2,3,7,8-TCDD, and diesel particulate matter (DPM). A cancer risk assessment was conducted to determine the health effects of exposure to the six HAPs by using the AERMOD model. Results indicated that the emission of benzene, formaldehyde, 1,3-butadiene, arsenic and DPM was 184.5; 227.3; 68.0; 238, and 316 ton year-1 , respectively, and the emission of 2,3,7,8-TCDD was 4,994 mg-TEQ year-1. Benzene (86%), formaldehyde (69%), and 1,3-butadiene (77%) were mainly emitted from on-road mobile sources. Arsenic (70%) and 2,3,7,8-TCDD (about 100%) were mainly emitted from stationary sources and DPM was emitted from diesel engines, port operations and ocean-going vessels. Spatial air toxic distribution indicated that the highest concentration of DMP, benzene, formaldehyde, and 1.3-butadiene occurred on the highway and in the downtown district due to their high traffic volume. DPM occupied more than 80% of total cancer risk in the region, followed by 1,3-butadiene, benzene, formaldehyde, arsenic, and 2,3,7,8-TCDD. In the industrial and residential complex area, about 99% of the cancer risk stemmed from on-road vehicles and port operations due to hazardous air pollutant emissions, especially DPM. The control scenario was made huge efforts to reduce the emission, however the results indicated only reduced the overall cancer risk assessment by 10%-15%. Policy makers have to think carefully about whether implementing the kind of emissions regulations simulated in this control scenario will need to be enhanced with additional measures to further reduce the risk of air pollution for human health.