With the increasing occurrence of extreme temperature events due to climate change, the attention has been predominantly focused on the effects of heat waves and cold spells on morbidity and ...mortality. However, the influence of these temperature extremes on blood parameters has been overlooked.
We conducted a cohort study involving 2,752 adult blood donors in Tianjin, China, between January 18, 2013, and June 25, 2021. The generalized additive mixed model was used to investigate the effects and lagged effects of heat waves and cold spells on six blood parameters of blood donors, including alanine aminotransferase (ALT), white blood cell count (WBC), red blood cell count (RBC), hemoglobin (HB), hematocrit (HCT), and platelet count (PLT). Subgroup analyses were stratified by sex, age, and BMI.
Heat waves and cold spells are associated with changes in blood parameters, particularly HB and PLT. Heat waves increased HB and PLT, while cold spells increased HB and decreased PLT. The effect of heat waves is greater than that of cold spells. The largest effect of heat waves on HB and PLT occurred at lag1 with 2.6 g/L (95% CI: 1.76 to 3.45) and lag7 with 9.71 × 10^9/L (95% CI: 6.26 to 13.17), respectively, while the largest effect of cold spells on HB and PLT occurred at lag0 with 1.02 g/L (95% CI: 0.71 to 1.33) and lag2 with -3.85 × 10^9/L (95% CI: -5.00 to -2.70), respectively. In subgroup analysis, the effect of cold spells on ALT was greater in the 40-49 age group.
We indicated that heat waves and cold spells can impact hemoglobin and platelet counts in the human body. These findings provide evidence linking heat waves or cold spells to diseases and may reduce health risks caused by extreme temperature events.
With the implementation of strict emission regulations and the use of cleaner fuels, there has been a considerable reduction in exhaust emissions. However, the relative contribution of tire wear ...particles (TWPs) to particulate matters is expected to gradually increase. This study conducted laboratory wear experiments on tires equipped on domestically popular vehicle models, testing the factors and particle size distribution of TWPs. The results showed that the content of tire wear particle emission was mainly ultrafine particles, accounting for 94.80% of particles ranging from 6 nm to 10 μm. There were at least two concentration peaks for each test condition and sample, at 10~13 nm and 23~41 nm, respectively. The mass of TWP emission was mainly composed of fine particles and coarse particles, with concentration peaks at 0.5 μm and 1.3–2.5 μm, respectively. Both the number and mass of TWPs exhibited a bimodal distribution, with significant differences in emission intensity among different tire samples. However, there was a good exponential relationship between PM10 mass emissions from tire wear and tire camber angle. The orthogonal experimental results showed that the slip angle showed the greatest impact on TWP emission, followed by speed and load, with the smallest impact from inclination angle.
Brake wear is an important but unregulated vehicle-related source of atmospheric particulate matter (PM). The single-particle spectral fingerprints of brake wear particles (BWPs) provide essential ...information for understanding their formation mechanism and atmospheric contributions. Herein, we obtained the single-particle mass spectra of BWPs by combining a brake dynamometer with an online single particle aerosol mass spectrometer and quantified real-world BWP emissions through a tunnel observation in Tianjin, China. The pure BWPs mainly include three distinct types of particles, namely, Ba-containing particles, mineral particles, and carbon-containing particles, accounting for 44.2%, 43.4%, and 10.3% of the total BWP number concentration, respectively. The diversified mass spectra indicate complex BWP formation pathways, such as mechanical, phase transition, and chemical processes. Notably, the mass spectra of Ba-containing particles are unique, which allows them to serve as an excellent indicator for estimating ambient BWP concentrations. By evaluating this indicator, we find that approximately 4.0% of the PM in the tunnel could be attributable to brake wear; the real-world fleet-average emission factor of 0.28 mg km−1 veh−1 is consistent with the estimation obtained using the receptor model. The results presented herein can be used to inform assessments of the environmental and health impacts of BWPs to formulate effective emissions control policies.
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•Single-particle mass spectral signatures of brake wear particles were obtained.•Pure brake wear particles mainly include three distinct chemical types of particles.•A new method was developed to quantify the real-world emission of brake wear.•Approximately 4.0% of the PM in the tunnel was attributable to brake wear.
Vehicle exhaust is the primary source of polycyclic aromatic compounds (PACs). Real road tests using a portable vehicle measurement system on light-duty gasoline vehicles and light-duty diesel trucks ...were conducted to investigate gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and oxy-PAHs (OPAHs) in vehicle exhaust with different emission standards, fuel types, and altitudes. The results showed that with the tightening of emission standards, the overall emission factors (EFs) of PACs decreased. Compared with China V diesel vehicles, the emissions of PAHs, OPAHs, and NPAHs from China VI diesel vehicles were 75.1 %, 84.4 %, and 61.2 % lower, respectively. With a ∼100 m increase in altitude, the EFs of PAHs, OPAHs, and NPAHs of diesel vehicles increased 1.88, 1.92, and 1.59 times due to incomplete combustion. In addition, the EFs of PAHs and OPAHs in gasoline vehicles were lower than those in diesel vehicles. In contrast, the proportion of PAHs with highly toxic components, such as dibenzoa,hanthracene (DahA) and benzoapyrene (BaP), and the EFs of gas-phase NPAHs in gasoline vehicles were higher than those in diesel vehicles. Furthermore, the emissions of 1,8-DNP from diesel vehicles cannot be disregarded. 1,8-DNP was the main gas-phase NPAHs emitted by China VI and China V diesel vehicles, accounting for 49.3 % and 26.0 %, respectively. Moreover, gas-phase PACs contributed more to the EFs than particle-phase PACs, whereas particle-phase PACs have greater toxic effects. Although the EFs of PAHs are more than 100 times those of NPAHs, the toxic equivalent concentrations (TEQBaP) of PAHs in diesel and gasoline vehicles were approximately 6.5 times and 35 times those of NPAHs. The spatial distribution characteristics revealed that PACs emissions were mainly concentrated in urban areas and highways, and the differences in the toxicity of PACs emissions between different cities depended on the proportion of diesel vehicles. The average TEQBaP of PAHs and NPAHs in Haidong, Haibei, Huangnan, Hainan, Guoluo, and Yushu was 8.42 μg/m3 and 0.36 μg/m3, respectively, while those of Xining and Haixi were 0.24–0.29 μg/m3 and 0.09–0.108 μg/m3 higher, respectively. This study provides a comprehensive understanding of the emission characteristics, health risks, and spatial distribution of PACs from diesel and gasoline vehicle PACs in urban areas.
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•Vehicle exhaust were tested with different conditions using PEMS.•Large gaps were found in 1,8-DNP from diesel vehicles comparing with previous studies.•EFs of PACs increased 1.59–1.92 times with altitude increment of ∼100 m.•DahA and BaP had important contributions in gasoline vehicles than diesel vehicles.
Volatile organic compounds (VOCs) are critical precursors of photochemical smog. Quantitatively evaluating the VOC sources and their contributions to ozone formation provides valuable information for ...photochemical pollution abatement. However, due to the fast oxidization of VOCs during transport in the atmosphere, source apportionment via receptor models using measured VOC data inevitably has a systematic deviation. In this study, we conducted a field measurement of VOCs at a suburban site in Beijing and evaluated the influences of photochemical oxidization on VOC source contributions. The initial VOC concentration, defined as the sum of measured VOC concentration and their photochemical losses. The real-time photochemical age-based parameterization method and a sequential reaction model were applied to characterize the photochemical loss of VOCs. Also, the photochemical loss of VOCs was considered in the he positive matrix factorization (PMF) model. Photochemical losses, on average, accounted for 5.6% of total VOCs (TVOCs) and 59.2% of alkenes, indicating that the impact of photochemical reaction cannot be ignored. Alkanes were the most significant contributors to both measured and initial TVOCs, while the alkenes and oxygenated volatile organic compounds (OVOCs), especially ethylene and isoprene, contributed the most to ozone formation potential. By adopting the positive matrix factorization model, seven VOC sources were identified for both measured and initial TVOCs. Vehicular emissions, industrial sources, and biomass burning were the top three contributors to ambient TVOC. Photochemistry significantly influenced the results of source apportionment, e.g., the contribution of biogenic sources (+4.4%), industrial emissions (+2.5%) and solvent usage (+2.5%) based on initial VOCs were larger than that of measured VOCs, while the contribution of gasoline vehicular emissions (−9.9%) was lower than that of measured VOCs. Our results highlight the necessity of adequately considering the photochemical loss of VOCs for accurately apportioning the emission sources.
•Photochemical reaction significantly influenced the VOC concentration.•Photochemical loss accounted for 26.3% initial alkenes and 13.1% initial aromatics.•Vehicle and combustion emissions were the largest contributors to both measured and initial VOC concentration.•Biogenic sources, industrial emissions and solvent usage based on initial VOCs were larger than that of measured VOCs.
This study used a portable emission measurement system (PEMS) to investigate the emission characteristics of three Euro V buses (a CNG bus, an LNG bus and a hybrid-CNG bus) under real-traffic ...conditions. The results showed that the emission factor of gaseous pollutants decreased gradually with increasing driving speed. The LNG bus showed the highest emission characteristics, especially the emissions of CO, NOx, PM and BC. Although the NOx emission factor for the LNG bus was the highest (23.56 g/km), its NO2 emission factor (0.82 g/km) was lower than that of the CNG bus (1.58 g/km). Moreover, the particle size of the particulate matter emitted by the LNG buses was large, and the ratio of BC/PM was about 40%, which was much higher than those of the other two buses (7.59% and 33.11% for the CNG bus and hybrid-CNG buses, respectively). Compared with the CNG bus, the hybrid-CNG bus could effectively reduce particle number emissions by 59.1%, mainly by reducing the emission of nucleation-mode particles with particle size less than 30 nm. However, the emissions factors of other pollutants of the hybrid-CNG bus were higher than those of the CNG bus, especially the emission of black carbon, which was 66% higher.
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•The emission characteristics of CNG, LNG and hybrid-CNG buses had been studied.•Compared with CNG buses, the LNG bus emitted more NOx and less NO2.•99.4% particles emitted by CNG buses were nucleation-mode particles.•The particle size distribution of the CNG bus was unimodal.•This study firstly reported BC emission characteristics of actual road NG buses.
With implementing vehicle emission control policies, tailpipe particulate emissions have been gradually controlled, and the relative contribution of non-tailpipe particulate emissions, such as brake ...and tire wear, has further increased. A unified and scientific method for sampling non-tailpipe particulate matter (PM) emissions is essential to improve the accuracy of the emission characteristics and factors. This study proposes a novel sampling method based on real-world driving conditions to obtain information on emissions and extract characteristic conditions for tire and brake pad wear. We extracted 200 representative braking segments for simulation experiments based on road type, initial and final velocities, temperature, and deceleration rate. Two standard test cycles to simulate the tire wear conditions of the front and rear wheels were constructed based on velocity, lateral, and vertical forces. Under the real-world driving condition test cycle, the emission factors of PM2.5 and PM10 for brake wear particles of passenger vehicles were 2.66 mg/km and 11.65 mg/km, respectively. In contrast, the emission factors of PM2.5 and PM10 for tire wear particles were 0.21 mg/km and 1.27 mg/km, respectively. Moreover, this study provides insights and basic data for localizing and improving the emission model, which can enhance its applicability and accuracy.
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•A novel sampling method based on real-world driving conditions was provided.•200 representative braking segments for brake wear test were extracted.•A standard test cycle for tire wear based on real-world road driving was developed.•The emission factors of PM from brake and tire wear were obtained.•The EFs of brake and tire wear could be localized corrections of the MOVES model.
Brake wear particles (BWPs) are considered one of the most significant non-exhaust particle emission sources from motor vehicles. Previous studies have primarily focused on BWPs from conventional ...fuel vehicles (CFVs), with limited research available on BWPs from new energy vehicles (NEVs). We developed an independent BWP emission testing system applicable to NEVs and conducted BWP emission tests on representative NEVs and CFVs under various testing cycles via a chassis dynamometer. The BWP emission characteristics of the NEVs equipped with regenerative braking system significantly differed from those of gasoline vehicles. For transient emission characteristics, gasoline vehicles exhibited higher peak concentrations during brake events than brake drag events, while those with regenerative braking exhibited the opposite feature. Under continuous braking, the concentration of ultrafine particles emitted by NEVs was reduced by more than 3 orders of magnitude compared to gasoline vehicles. In terms of single-particle morphology, BWPs could be mainly divided into three categories: carbonaceous particles, iron-rich particles, and mixed metal particles. We obtained realistic emission characteristics of BWPs from NEVs, which could provide data support and a scientific basis for the formulation of relevant emission standards and control measures in the future.
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•We develop and establish an independent brake wear particle emission testing system.•The brake wear particles from new energy vehicles significantly differ from gasoline vehicles.•New energy vehicles exhibit higher peak concentrations during brake drag than actual braking.•Carbonaceous particles, iron-rich particles and mixed metal particles were the three categories.
Tire wear is one of the major sources of traffic-related particle emissions, however, laboratory data on the components of tire wear particles (TWPs) is scarce. In this study, ten brands of tires, ...including two types and four-speed grades, were chosen for wear tests using a tire simulator in a closed chamber. The chemical components of PM2.5 were characterized in detail, including inorganic elements, water-soluble ions (WSIs), organic carbon (OC), elemental carbon (EC), and polycyclic aromatic hydrocarbons (PAHs). Inorganic elements, WSIs, OC, and EC accounted for 8.7 ± 2.1%, 3.1 ± 0.7%, 44.0 ± 0.9%, and 9.6 ± 2.3% of the mass of PM2.5, respectively. The OC/EC ratio ranged from 2.8 to 7.6. The inorganic elements were dominated by Si and Zn. The primary ions were SO42− and NO3−, and TWPs were proven to be acidic by applying an ionic balance. The total PAHs content was 113 ± 45.0 μg g−1, with pyrene being dominant. In addition, the relationship between the chemical components and tire parameters was analyzed. Inorganic elements and WSIs in TWPs were more abundant in all-season tires than those in winter tires, whereas the content of PAHs was the opposite. The mass fractions of OC, Si, and Al in the TWPs all showed increasing trends with increasing tire speed grade, but the PAHs levels showed a decreasing trend. Ultimately, to provide more data for further research, a TWPs source profile was constructed considering the tire weighting factor.
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•The chemical component contents depended strongly on tire type and speed grade•Tire wear particles were acidic based on the equivalent concentration equation•Total carbon accounted for nearly half of the components of tire wear particle•The weighted source profile would provide data for source apportionment
Brake wear emission contributes to an increasingly significant proportion of vehicle-related particulate matter, but knowledge of its emission features and determining factors is still highly ...insufficient. Here, brake dynamometer experiments were conducted under controlled variables tests and real-world driving conditions to systematically investigate brake wear particle (BWP) emission. Compared to the decelerating process, the separating of pads and disc releases more BWPs, accounting for 47–76% of the total PM2.5 mass. Particle number and mass distributions exhibit bimodal (< 0.01 µm and 0.8–1.2 µm) and unimodal (2–5 µm) patterns, respectively. Larger speed reduction exponentially amplifies BWP emission, and the significant enhancement of nanoparticles is proved to be related to the evaporation of organic constituents in the pads with threshold ranging from 170 °C to 270 °C. Emissions from front and rear brake assemblies don’t agree with braking torque distribution, mainly attributive to the different braking pressures. A parameterization scheme for BWP emission based on kinetic energy loss is further established and proved to sufficiently predict the variation of BWP under real-world driving conditions. Being corrected by 1.8th power of the initial speed, the scheme improves the prediction.
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•Break wear nanoparticles are proved to form from organics.•Multiple influencing factors were explored to determine the brake wear PM emissions.•Front and rear brake wear PM emissions do not follow the braking torque distribution.•Kinetic energy loss can predict brake wear PM emissions under real-word conditions.
