Motor vehicles are the main source of carbon monoxide (CO) Under multiple sponsorship, two major vehicle emissions studies were conducted: one in Fort McHenry tunnel (under the Baltimore Harbor) in June 1992 and the other in the Tuscarora Mountain tunnel in south-central Pennsylvania (Pennsylvania Turnpike) in September 1992 The cars at both sites tended to be newer than elsewhere (median age was < 4 years), and much better maintained as judged by low CO/CO2 ratios and other emissions characteristics Measured CO/CO2 ratios agreed with concurrent roadside infrared remote sensing measurements on light-duty vehicles Remote sensing measurements on heavy-duty diesels were obtained for the first time and were roughly in agreement with the regular (bag sampling) tunnel measurements in both CO/CO2 and HC/CO2 ratios

Real-world automotive emissions: Summary of studies in the Fort McHenry and Tuscarora Mountain tunnels. Final report

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the atmosphere and they mostly stem from the imperfect combustion of fossil fuels and biofuels. PAHs are inherently associated with homogenous fine particles or distributed to different-sized particles during the aging of air masses. PAHs carried by fine particles undergo a long-range transport to remote areas while those adsorbed on coarse particles have a shorter lifetime in ambient air. More importantly, PAHs with higher molecular weights tend to be bound with finer particles and can deeply enter the lungs, posing severe health risks to humans. Thus, the environmental fate and health effects of particulate PAHs are strongly size-dependent. This review summarizes the size distributions of particulate PAHs freshly emitted from combustion sources as well as the distribution patterns of PAHs in ambient particles. It was found that PAHs from stationary sources are primarily bound to fine particles, which are slightly larger than particles to which PAHs from mobile sources are bound. In ambient air, particulate PAHs are distributed in larger size modes than those in the combustion fume, and the particle size decreases with PAH molecular weight increasing. The relevant mechanisms and influencing factors of particle size distribution changes are illustrated in this article, which are essentially attributed to combustion and ambient temperature as well as the physical and chemical properties of PAHs. Overall, the study on the particle size distribution of PAHs will contribute for a full understanding of the origin, atmospheric behaviors and health effects of particulate PAHs.

Size distribution of particulate polycyclic aromatic hydrocarbons in fresh combustion smoke and ambient air: A review.

Large-scale industrial activities emit large amounts of potentially toxic elements (PTEs) in the form of particulate pollutants. Most of these pollutants settle on the road and eventually mix into the road dust. In the long-term, they will have adverse effects on ecosystems and human health. In this research, various analytical methods were used to assess the pollution characteristics of the 12 PTEs (Mn, Ni, Cu, Zn, Hg, Cd, As, Cr, Pb, Tl, Co, and Sb) in the study area, and geo-statistics served to analyze the spatial distribution characteristics of PTEs. Combining the potential ecological risk method and health risk assessment with positive matrix factorization (PMF) from different sources entailed a quantitative evaluation. Taking a large Cu smelter in central China as an example, three sources were quantitatively apportioned, these being smelting emissions and transportation activities (54.04%), daily human activities and natural existence (33.36%), as well as coal-fired activities of industrial production (12.60%) separately. The results showed that in more than 90% of the samples, Cd, Cu, Hg, Pb, As, Zn, Tl and Sb indicated high levels of contamination. In terms of spatial distribution, the high-value PTEs were mainly distributed near the smelter. Regarding ecological risk, smelting emissions and transportation activities were the greatest source, followed by coal-fired activities. As for human health risk, adults did not have significant non-carcinogenic risk, but children had obvious non-carcinogenic risk. Among different sources, the risk of smelting emissions and transportation activities were the highest. After calculating the value of carcinogenic risks, it emerged there was no obvious carcinogenic risk for children and adults in the study area. The comprehensive approach combining risk assessments with source identification is very effective in identifying prior pollutants and important sources of pollution. They can provide a good theoretical reference for effective prevention and control of pollution.

A comprehensive exploration of risk assessment and source quantification of potentially toxic elements in road dust: A case study from a large Cu smelter in central China

Heavy-duty diesel vehicles dominate vehicle emissions in a tunnel study in northern China.

Investigating vertical distribution patterns of lower tropospheric PM 2.5 using unmanned aerial vehicle measurements

Polycyclic aromatic hydrocarbons (PAHs) in PM 10 and PM2.5 samples were collected at a road tunnel inlet and outlet in Nanjing, China. Particulate matter and PAHs species mass concentrations, especially higher molecular weight PAHs, both increased noticeably from the tunnel inlet to its outlet. In the tunnel, fluoranthene , pyrene, chrysene, benz[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[ghi]perylene, indeno[1,2,3-cd]pyrene and coronene were abundant PAHs species, all of which were identified as diesel and gasoline vehicle markers. These species had good correlation. Emission factors of higher molecular weight PAHs were significantly higher than those of lower molecular weight PAHs. The PAHs from traffic-related sources were primarily distributed in fine particulate matter compared with coarse particulate matter. Diagnostics ratios and principal component analysis were used to distinguish PAHs sources. The results showed that vehicle exhaust emissions (including those from diesel and gasoline vehicles) contributed 61.66% and 62.22% to the PAHs for PM 10 and PM2.5 , respectively, while the corresponding values for vehicle non-exhaust emissions (e.g., road dust, brake line, and tyre wear) were 22.09% and 19.34%. PAHs source profiles from vehicles non-exhaust emissions and precise quantitative analysis for PAHs source apportionment from traffic-related sources are both urgently needed.

Characteristics, emissions and source identifications of particle polycyclic aromatic hydrocarbons from traffic emissions using tunnel measurement

Elemental composition and risk assessment of heavy metals in the PM10 fractions of road dust and roadside soil

Optimal location of a particulate matter sampling head outside an unmanned aerial vehicle

Respirable particulate matter(PM2.5)samples were collected at different locations (inside and outside the tunnel) at the Zhang Zizhong Tunnel in Tianjin in September 2015. Seventeen inorganic elements were measured, and the sources were analyzed by the PCA receptor model. The results show that the daily average concentration of PM2.5 inside and outside the tunnel is (94.79±62.78) μg·m-3 and (83.92±61.60) μg·m-3, respectively. The concentration during the working day is higher than on a non-working day, and, to a certain extent, PM2.5 concentration in the tunnel during peak periods is correlated with the vehicle flow, which indicates that PM2.5 concentration is affected by motor vehicle pollution seriously. In the tunnel, the concentrations of Si, Fe, Al, Ca, and Mg are higher, the mass fraction reach 98.48% of all analyzed elements and these elements are less affected by vehicles. Fe and trace heavy metals (Zn, Cu, and Pb) are related closely to motor vehicle pollution. From the Wilcoxon Signed-Rank test, there are significant differences in Ba, Cu, Zn, Mo, Sn, and Sb inside and outside the tunnel. Enrichment factors inside and outside the tunnel show that the enrichment factor ratios of Co, Mn, Cr, Ca, Mg, Ba, Fe, Mo, and V are less than 5, which are mainly from the crust. In addition, the enrichment factor ratios of Cu, Zn, Pb, Sn, Sb, and Cd are greater than 5, which are affected largely by anthropogenic sources. The factor analysis indicates that the main pollution sources in the tunnel are the mixed sources of wear and the combustion of fuel, the dust, and the combustion of diesel vehicles. In addition, in order to analyze the source of motor vehicle pollution further, a factor analysis indicates that the main pollution sources are tire wear and exhaust emission, brake wear and exhaust emissions, and diesel emissions.

Characteristics of Particulate and Inorganic Elements of Motor Vehicles Based on a Tunnel Environment

The pollution characteristics and emission factors (EFs) of the volatile organic compounds (VOCs) of vehicles were investigated using the tunnel test method on weekdays and weekends in the Wujinglu Tunnel in Tianjin, China. Gas samples in the tunnel were collected with 3.2 L stainless steel canisters and 99 VOCs species were analyzed by gas chromatography-mass spectrometry (GC-MS). The concentration levels, variation characteristics, and EFs of the VOCs were analyzed. The ozone formation potentials (OFPs) and secondary organic aerosol formation potentials (SOAFPs) of the VOCs in the tunnel were calculated. Moreover, a comparison of the study results with current literature was conducted. The total concentrations of VOCs at the inlet and midpoint are (190.85±51.15) μg·m-3 and (257.44±62.02) μg·m-3, respectively. The total EFs are (45.12±10.97) mg·(km·veh)-1 and the EFs for alkanes, alkenes, alkynes, aromatics, halocarbons, and oxygenated volatile organic compounds (OVOCs) are (22.79±7.15), (5.04±1.20), (0.78±0.34), (9.86±2.81), (0.26±0.17), and (6.25±2.27) mg·(km·veh)-1, respectively. They are notably smaller than the values obtained in a previous test in 2009. Isopentane, toluene, ethylene, methyl tert-butyl ether (MTBE), and ethane were the top five species among the VOC EFs. The ratios of methyl tert-butyl ether/benzene (MTBE/B) and methyl tert-butyl ether/toluene (MTBE/T) are 1.07 and 0.77, respectively. This implies that the contribution of evaporative emissions from vehicles to VOCs emissions cannot be ignored. The OFPs and SOAFPs in the tunnel are (145.50±37.85) and (43.87±12.75) mg·(km·veh)-1, respectively. Compared with the test in 2009, the OFPs and SOAFPs are 94.23% and 90.88% smaller, respectively. The sharp decrease of the OFPs and SOAFPs is closely related to stricter emission standards and the upgrade of oil products.

Jing Zhang

Papers

Characteristics, emissions and source identifications of particle polycyclic aromatic hydrocarbons from traffic emissions using tunnel measurement

Elemental composition and risk assessment of heavy metals in the PM10 fractions of road dust and roadside soil

Optimal location of a particulate matter sampling head outside an unmanned aerial vehicle

Characteristics of Particulate and Inorganic Elements of Motor Vehicles Based on a Tunnel Environment

Pollution Characteristics and Emission Factors of VOCs from Vehicle Emissions in the Tianjin Tunnel