Particle-phase polycyclic aromatic hydrocarbon emissions from non-catalysed, in-use four-stroke scooters

Effect of Sampling Conditions on the Sub-23 nm Nonvolatile Particle Emissions Measurements of a Moped

The solid (or nonvolatile) particle number (SPN) emissions of light-duty and heavy-duty vehicles and engines are regulated in the European Union. The measurements are conducted from the tailpipe during on-road tests, but from the dilution tunnel in the laboratory under controlled conditions. Recently, dedicated laboratory studies for the evaluation of the measurement uncertainty at the two sampling locations found differences due to the formation of nonvolatile particles, i.e., particles that do not evaporate in the thermal pre-treatment part of the particle number systems. In order to investigate the origin of these particles, measurements at the tailpipe, the transfer tube, and the dilution tunnel were conducted with cold and hot dilution and instruments with different lower detection limits (4 nm, 10 nm, and 23 nm). The results showed that sub-23 nm nonvolatile particles could be detected in the dilution tunnel, but not at the tailpipe, due to growth of low volatility compounds in the transfer tube and the finite residence time in the thermal pretreatment part of the particle number systems. When measuring below 23 nm, diluting at the tailpipe or reducing the residence time in the transfer tube to the dilution tunnel is important in order to minimize such differences.

Particulate Emissions of Euro 4 Motorcycles and Sampling Considerations

The scientific literature indicates that solid particle number (SPN) emissions of motorcycles are usually higher than that of passenger cars. The L-category (e.g., mopeds, motorcycles) Euro 4 and 5 environmental steps were designed to reduce the emissions of particulate matter and ozone precursors such as nitrogen oxides and hydrocarbons. In this study the SPN emissions of one moped and eight motorcycles, all fulfilling the Euro 4 standards, were measured with a SPN measurement system employing a catalytic stripper to minimize volatile artefacts. Although the particulate matter mass emissions were <1.5 mg/km for all vehicles tested, two motorcycles and the moped were close to the SPN limit for passenger cars (6 × 1011 particles/km with sizes larger than 23 nm) and four motorcycles exceeded the limit by a factor of up to four. The measurement repeatability was satisfactory (deviation from the mean 10%) and concentration differences between tailpipe and dilution tunnel were small, indicating that performing robust SPN measurements for regulatory control purposes is feasible. However, steady state tests with the moped showed major differences between the tailpipe and the dilution tunnel sampling points for sub-23 nm particles. Thus, the measurement procedures of particles for small displacement engine mopeds and motorcycles need to be better defined for a possible future introduction in regulations.

Effect of air pollutants and toxic emissions from various mileage of motorcycles and aerosol related carcinogenicity and mutagenicity assessment

This research investigates the mileage and the health risk assessment of aerosol carcinogenicity and mutagenicity emitted by ten in-use motorcycles. The total p-PAHs emission factor of ten in-use motorcycles are 676.3 μg km^-1 with average of 67.6 ± 13.6 μg km^-1. Naphthalene (Nap) shows the largest emission factors, followed by phenanthrene (PA) and fluoranthen (FL). The mileage present high correlation coefficient (Rsp = 0.681) with CO. CO is associated with cumulative mileage leading to bad combustion efficiency, which caused low to high relationship for total p-PAHs (Rsp = 0.388), PM_2.5 (Rsp = 0.680) and NOx (Rsp = 0.799). Both PM_2.5 and total p-PAHs are generally generated via incomplete combustion and the results expressed the moderate to high correlation (Rsp = 0.578, 0.898) with NOx. Taking into consideration of high-mileage motorcycles (30,001-50,000 km), the toxic equivalent of carcinogenicity and mutagenicity exhaust are about 4.67, 1.99 and 3.89, 2.0 times higher than low (10,001-20,000 km) and middle (20,001-30,000 km) cumulative mileages, respectively. Therefore, in the conclusion of our study in compared with that of other research directed the fact that lower carcinogenicity and mutagenicity emission factor were found at lower cumulative mileages motorcycles however, the impact increases with the high cumulative mileage motorcycles.

Primary Particulate Matter Emitted from Heavy Fuel and Diesel Oil Combustion in a Typical Container Ship: Characteristics and Toxicity

Container ships have been widely recognized as an important emission source within maritime transport. Heavy fuel oil (HFO) and diesel oil (DO) are the two most commonly used fuels. This study reports the characteristics and toxicities of particulate matter (PM) emissions from HFO and DO combustion in a typical container ship. The PM number size distribution possesses a bimodal structure with peaks at ∼20 nm and ∼100 nm. The PM_2.5 emission factors (EFs) are 3.15 ± 0.39 and 0.92 ± 0.02 g/kg fuel for HFO and DO, respectively. The benzo[a]pyrene equivalent carcinogenic potency (BaP_eq) of 16 polycyclic aromatic hydrocarbons contained in HFO and DO PM_2.5 is approximately 0.81 ± 0.10 and 0.12 ± 0.04 mg/kg fuel, respectively. BaP_eq concentration shows an increasing tendency with decreased PM size. The reactive oxygen species activity and cytotoxicity of HFO PM_2.5 samples are ∼2.1 and ∼2.5 times higher than those of DO PM_2.5 samples, respectively. These health risks are both significantly attributed to the BaP_eq content in PM_2.5 with correlations of 0.86-0.92. Furthermore, the examined biological effects are much greater than those of atmospheric PM_2.5 collected in Shanghai. Our results imply that better fuel quality is important for improving air quality and reducing health risks.

Physicochemical Characterization of Exhaust Particulates from Gasoline and Diesel Engines by Solid-Phase Micro Extraction Sampling and Combined Raman Microspectroscopic/Fast Gas-Chromotography Mass Spectrometry Analysis

Ambient Particulate Matter (PM) has been shown to be associated with cardiopulmonary diseases and lung cancer. Several groups of investigators have shown that the size of the airborne particles and their surface area determine the potential to elicit inflammatory injury and other mechanisms of adverse cellular effects. Because traffic is an important source of PM, it seems obvious that physicochemical characterization of vehicles exhaust emission has an important impact on both quantitative and qualitative aspects of ambient PM. In the present study the exhaust emissions of 8 vehicles of different categories were analyzed to attempt to differentiate them. For such purpose the particulate was collected on SPME fibers exposed to the exhaust emission for 150 s. The particulate was first characterized by micro-Raman spectroscopy and then subjected to Fast Gas Chromatography-Mass Spectrometry analyses for the chemical identification of the Polycyclic Aromatic Hydrocarbons (PAHs) compounds, the organic fraction of particulate matter in air pollution with a major role in the toxicity, notably via its effects on inflammation. Both the particle count and the PAHs compositional data were assembled to be interpreted by Principal Components Analysis. This multivariate analysis grouped the data according mainly to the naphthalene amount, as well as the volume concentration of the particles smaller than 0.5 μm, suggesting that the different exhaust emissions could be easily differentiated. With this new methodology, future research should aim at establishing a mechanism of formation during internal engine combustion processes in order to obtain a clearer picture of the inflammatory and carcinogenic mechanisms of PM in the lungs.

Polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons in particulates emitted by motorcycles

We determined eleven PAHs and four NPAHs in particulates and regulated pollutants (CO, CO2, HC, NOx, PM) exhausted from motorcycles to figure out the characteristics of motorcycle exhausts. Fluoranthene and pyrene accounted for more than 50% of the total detected PAHs. Among four detected NPAHs, 6-nitrochrysene and 7-nitrobenz[a]anthracene were the predominant NPAHs and were highly correlated relationship with their parent PAHs (R = 0.93 and 0.97, respectively). The PM and HC emissions tended to be close to the PAH emissions. NOx and NPAHs were negatively correlated. Despite their small engine size, motorcycles emitted much more PM and PAHs, showed stronger PAH-related carcinogenicity and indirect-acting mutagenicity, but weaker NPAH-related direct-acting mutagenic potency than automobiles. This is the first study to analyze both PAHs and NPAHs emitted by motorcycles, which could provide useful information to design the emission regulations and standards for motorcycles such as PM.