Development of sleepiness in professional truck drivers: Real-road testing for driver drowsiness and attention warning (DDAW) system evaluation.

All new vehicle types within the European Union must now be equipped with a driver drowsiness and attention warning system starting from 2022. The specific requirements for the test procedure necessary for type approval are defined in the Annex of EU Regulation C/2021/2639. The objectives of this study were to: (i) investigate how sleepiness develops in professional truck drivers under real-road driving conditions; and (ii) assess the feasibility of a test procedure for validating driver drowsiness and attention warning systems according to the EU regulation. Twenty-four professional truck drivers participated in the test. They drove for 180 km on a dual-lane motorway, first during daytime after a normal night's sleep and then at nighttime after being awake since early morning. The results showed higher sleepiness levels during nighttime driving compared with daytime, with a faster increase in sleepiness with distance driven, especially during the night. Psychomotor vigilance task results corroborated these findings. From a driver drowsiness and attention warning testing perspective, the study design with sleep-deprived drivers at night was successful in inducing the targeted sleepiness level of a Karolinska Sleepiness Scale score of ≥ 8. Many drivers who reported a Karolinska Sleepiness Scale ≥ 8 during the drives also acknowledged feeling sleepy in the post-drive questionnaire. Reaching high levels of sleepiness on real roads during daytime is more problematic, not the least from legal and ethical perspectives as higher traffic densities during the daytime lead to increased risks.

Societal Co-benefits of Zero-Emission Vehicles in the Freight Industry.

This study was set in the Greater Toronto and Hamilton Area (GTHA), where commercial vehicle movements were assigned across the road network. Implications for greenhouse gas (GHG) emissions, air quality, and health were examined through an environmental justice lens. Electrification of light-, medium-, and heavy-duty trucks was assessed to identify scenarios associated with the highest benefits for the most disadvantaged communities. Using spatially and temporally resolved commercial vehicle movements and a chemical transport model, changes in air pollutant concentrations under electric truck scenarios were estimated at 1-km2 resolution. Heavy-duty truck electrification reduces ambient black carbon and nitrogen dioxide on average by 10 and 14%, respectively, and GHG emissions by 10.5%. It achieves the highest reduction in premature mortality attributable to fine particulate matter chronic exposure (around 200 cases per year) compared with light- and medium-duty electrification (less than 150 cases each). The burden of all traffic in the GTHA was estimated to be around 600 cases per year. The benefits of electrification accrue primarily in neighborhoods with a high social disadvantage, measured by the Ontario Marginalization Indices, narrowing the disparity of exposure to traffic-related air pollution. Benefits related to heavy-duty truck electrification reflect the adverse impacts of diesel-fueled freight and highlight the co-benefits achieved by electrifying this sector.

Domestic access to water in a decentralized truck-to-cistern system: a case study in the Northern Village of Kangiqsualujjuaq, Nunavik (Canada).

Municipal water supply through truck-to-cistern systems is common in northern Canada. Household satisfaction and concerns about water services likely impact user preferences and practices. This case study explores household perspectives and challenges with regard to domestic access to water in a decentralized truck-to-cistern system. A case study was conducted in the Northern Village of Kangiqsualujjuaq, Nunavik (Quebec, Canada). A paper-based questionnaire was completed by 65 households (one quarter of the population). Many households (37%) reported not drinking tap water from the truck-to-cistern system. Chlorine taste was a frequently reported concern, with those households being significantly less likely to drink water directly from the tap (p = 0.002). Similarly, households that reported a water shortage in the previous week (i.e., no water from the tap at least once) (33%) were more likely to express dissatisfaction with delivered water quantity (rs = 0.395, p = 0.004). Interestingly, 77% of households preferred using alternative drinking water sources for drinking purposes, such as public tap at the water treatment plant, natural sources or bottled water. The study underscores the importance of considering household perspectives to mitigate the risks associated with service disruptions and the use of alternative sources for drinking purposes.

A blueprint for a new commercial driving epidemiology: An emerging paradigm grounded in integrative exposome and network epistemologies.

Excess health and safety risks of commercial drivers are largely determined by, embedded in, or operate as complex, dynamic, and randomly determined systems with interacting parts. Yet, prevailing epidemiology is entrenched in narrow, deterministic, and static exposure-response frameworks along with ensuing inadequate data and limiting methods, thereby perpetuating an incomplete understanding of commercial drivers' health and safety risks. This paper is grounded in our ongoing research that conceptualizes health and safety challenges of working people as multilayered "wholes" of interacting work and nonwork factors, exemplified by complex-systems epistemologies. Building upon and expanding these assumptions, herein we: (a) discuss how insights from integrative exposome and network-science-based frameworks can enhance our understanding of commercial drivers' chronic disease and injury burden; (b) introduce the "working life exposome of commercial driving" (WLE-CD)-an array of multifactorial and interdependent work and nonwork exposures and associated biological responses that concurrently or sequentially impact commercial drivers' health and safety during and beyond their work tenure; (c) conceptualize commercial drivers' health and safety risks as multilayered networks centered on the WLE-CD and network relational patterns and topological properties-that is, arrangement, connections, and relationships among network components-that largely govern risk dynamics; and (d) elucidate how integrative exposome and network-science-based innovations can contribute to a more comprehensive understanding of commercial drivers' chronic disease and injury risk dynamics. Development, validation, and proliferation of this emerging discourse can move commercial driving epidemiology to the frontier of science with implications for policy, action, other working populations, and population health at large.

Mathematically Improved XGBoost Algorithm for Truck Hoisting Detection in Container Unloading.

Truck hoisting detection constitutes a key focus in port security, for which no optimal resolution has been identified. To address the issues of high costs, susceptibility to weather conditions, and low accuracy in conventional methods for truck hoisting detection, a non-intrusive detection approach is proposed in this paper. The proposed approach utilizes a mathematical model and an extreme gradient boosting (XGBoost) model. Electrical signals, including voltage and current, collected by Hall sensors are processed by the mathematical model, which augments their physical information. Subsequently, the dataset filtered by the mathematical model is used to train the XGBoost model, enabling the XGBoost model to effectively identify abnormal hoists. Improvements were observed in the performance of the XGBoost model as utilized in this paper. Finally, experiments were conducted at several stations. The overall false positive rate did not exceed 0.7% and no false negatives occurred in the experiments. The experimental results demonstrated the excellent performance of the proposed approach, which can reduce the costs and improve the accuracy of detection in container hoisting.

Constitutive expression of interleukin-27 diminishes proinflammatory cytokine production without impairing effector function of engineered T cells.

Immunomodulatory cytokines can alter the tumor microenvironment and promote tumor eradication. Interleukin (IL)-27 is a pleiotropic cytokine that has potential to augment anti-tumor immunity while also facilitating anti-myeloma activity. We engineered human T cells to express a recombinant single-chain (sc)IL-27 and a synthetic antigen receptor targeting the myeloma antigen, B-cell maturation antigen, and evaluated the anti-tumor function of T cells bearing scIL-27 in vitro and in vivo. We discovered that T cells bearing scIL-27 sustained anti-tumor immunity and cytotoxicity yet manifested a profound reduction in pro-inflammatory cytokines granulocyte-macrophage colony-stimulating factor and tumor necrosis factor alpha. IL-27-expressing T cells therefore present a potential avenue to avert treatment-related toxicities commonly associated with engineered T-cell therapy due to the reduced pro-inflammatory cytokine profile.

Quantification and molecular characterization of intact rotavirus species A (RVA) in municipal solid waste leachate.

AIMS: Leachate comprises a solid waste decomposition product found fresh in collection trucks or as an effluent in landfills. This study aimed to assess the occurrence, concentrations, and genetic diversity of intact rotavirus species A (RVA) in solid waste leachate. METHODS AND RESULTS: Leachate samples were concentrated by ultracentrifugation, treated with propidium monoazide (PMA), and exposed to LED photolysis. Treated and untread samples were extracted using the QIAamp Fast DNA Stool mini kit, and nucleic acids were screened for RVA employing a Taqman® Real-time PCR. The PMA RT-qPCR method detected RVA in eight out of nine truck samples and in 15.40% (2/13) of the landfill leachate samples. The RVA concentrations in the PMA-treated samples ranged from 4.57 × 103 to 2.15 × 107 genomic copies (GC) 100 mL-1 in truck leachate and from 7.83 × 103 to 1.42 × 104 GC 100 mL-1 in landfill samples. Six truck leachate samples were characterized as RVA VP6 genogroup I2 by partial nucleotide sequencing. CONCLUSIONS: The high intact RVA detection rates and concentrations in truck leachate samples indicate potential infectivity and comprise a warning for solid waste collectors concerning hand-to-mouth contact and the splash route.

A look through Latin America truck drivers' health, a systematic review and meta-analysis.

Heavy truck drivers represent a social group of great importance to any country's economy. Their professional activity requires a high level of dedication. Due to the irregular hours in their work routine and adopted habits, they mostly predispose them to a diversity of health problems. The purpose of this study is to perform a systematic review and meta-analysis aiming to identify the prevalence of diabetes, hypertension, and obesity in Latin American Truck Drivers. We searched the PubMed, Web of Science, Scopus and LILACS databases, for scientific publications articles, as reported by The PRISMA Statement. From 1,382, 7 studies were included according to the established criteria. The hypertension prevalence found was 34.2%, diabetes was of 9.2% and the highest prevalence found was for overweight and obesity (56%). Meta-analysis presented that drivers have a higher prevalence of overweight or obesity when compared to eutrophic individuals and that drivers with diabetes and hyperglycemia have a lower prevalence. Due to their work activity, their access to the health system is compromised limiting any type of monitoring of their health. This study showed that there is, in Latin America, an investment and assistance gap, both in the health sector and in the research section, for this professional category, which is so important to the economy of these countries. These data should help to identify the difficulties faced by this professional in health assistance, road safety, public safety, leisure and social life. This research also highlighted that they are young and already have the first sign of non-transmissible chronic diseases, which is overweight and obesity.

Impact of work and coping factors on mental health: Australian truck drivers' perspective.

INTRODUCTION: Truck driving is one of the most common male occupations worldwide. Drivers endure long working hours, isolation, separation from family, compromised sleep, and face rigid regulatory requirements. Studies have documented the work factors contributing to poor health outcomes, however these have not been explored in the Australian context. The aim of this grounded theory study was to explore the impact of work and coping factors on mental health of Australian truck drivers from their perspective. METHODS: Recruitment used a purposive snowball sampling, through social media campaigns and direct email invites. Interview data were collected via phone/teleconference, audio recorded and typed verbatim. Inductive coding and thematic analysis were completed with triangulation of themes. RESULTS: Seventeen interviews were completed (94% male). Six themes arose, two supporting (Connections; Coping methods), and four disrupting mental health (Compromised supports; Unrealistic demands; Financial pressures; Lack of respect). Drivers had concerns regarding the many things beyond their control and the interactions of themes impacting their health even further. CONCLUSION: This study explored the impact of work and coping factors affecting truck driver mental health in Australia. Themes described the importance of connections and coping methods drivers had to support their health. Many factors that compromised their health were often outside their control. These results highlight the need for a multi-faceted collaboration between stakeholders; the driver, employing companies, policy makers/regulators and the public to address the negative impact of truck driving on mental health.

Metabolic syndrome among commercial truck drivers: The relationship between condition prevalence and crashes.

BACKGROUND: Metabolic syndrome (MetS) is especially prevalent among US truck drivers. However, there has been limited research exploring associations between MetS conditions with roadway crashes among truck drivers. The objective of this paper is to assess relationships between specific combinations of individual MetS components and crashes and near-misses. METHODS: Survey, biometric, and anthropometric data were collected from 817 truck drivers across 6 diverse US states. Survey data focused on demographics and roadway safety outcomes, and anthropometric/biometric data corresponded to five MetS conditions (waist circumference blood pressure, hemoglobin A1c, triglycerides, and high-density lipoprotein [HDL] cholesterol). Logistic regression was used to calculate odds ratios of lifetime crashes and near-miss 1-month period prevalence associated with: 1) specific MetS conditions regardless of presence or absence of other MetS conditions, and 2) specific MetS conditions and counts of other accompanying MetS conditions. RESULTS: Hypertension was the MetS characteristic most strongly associated with lifetime crash and 1-month near-miss outcomes, while high triglycerides, low HDL cholesterol, and large waist circumference were most commonly present among groups of conditions associated with crashes and near-misses. Overall, an increasing number of specific co-occurring MetS conditions were associated with higher reporting of roadway crashes. CONCLUSIONS: Specific combinations and higher prevalence of MetS conditions were associated with increased frequency of reported crashes. Moreover, when the co-occurrence of MetS conditions is aggregated, a dose-response relationship with crashes appears. These results suggest that policy changes and interventions addressing MetS may increase driver health and reduce crash risk.

Fatal injuries associated with rear step riding among municipal solid waste collection workers (United States, 1984-2020).

BACKGROUND: United States solid waste workers suffer a high fatal injury rate due to their frequent exposures to refuse-vehicle-related hazards. The Occupational Safety and Health Administration (OSHA) allows workers to ride on the rear steps of a garbage truck (exterior riding) if employers abide by American National Standard Z245.1 (ANSI Z245.1). The State of California (CA) has banned exterior riding since 1984, and the City of New York (NYC) has implemented its own initiatives to prevent exterior riding deaths. METHODS: Fatal exterior riding incidents were identified from two online databases. Variables relating to deceased workers, employers, and injury circumstances were analyzed. RESULTS: The study identified 181 exterior riding deaths from 604 refuse-vehicle-related fatal incidents (deaths either directly caused by a refuse vehicle or one in which the victim was performing a refuse-vehicle-related task) in the United States (1984-2020). A total of 50 (27.6%) of the exterior riding deaths had no ANSI Z245.1 violations. Risk factors other than those addressed by ANSI Z245.1 contributed to these worker deaths. CONCLUSIONS: Exterior riding deaths identified by this study were all preventable. Temporary workers and workers in the public sector may be at higher risk for exterior riding deaths. Both CA and NYC had taken measures to prohibit the practice of exterior riding, and both had lower numbers of exterior riding deaths. ANSI Z245.1 and current OSHA enforcement policy do not address the inherent dangers of falling off a moving heavy vehicle while standing on a small and elevated platform, and are not effective in preventing fatal exterior riding incidents.

The Relationship between Insomnia and Lifestyle-Related Diseases among Japanese Male Truck Drivers.

Previously, insomnia and adverse lifestyle were prevalent among truck drivers, but the association between the two remains unknown in this particular occupational cohort. This study aimed to examine the relationship between insomnia and lifestyle-related diseases among truck drivers. We investigated 875 male truck drivers of the Japan Truck Association, Akita branch, as of July 2020. The definition of insomnia was based on the International Classification of Sleep Disorders, Third Edition (ICSD-3). Data from a self-administered questionnaire were merged with health records and health insurance claims data of 2020. In total, 40.1% had either one of the lifestyle-related diseases including hypertension (29.7%), diabetes mellitus (11.7%), and dyslipidemia (24.8%), whereas according to ICSD-3, 13.2% had insomnia. Multivariate logistic regression models demonstrated that individuals with insomnia had approximately 2-fold increased risk of having at least one lifestyle-related disease (p < 0.001), hypertension (p = 0.0027), diabetes mellitus (p = 0.0654) and dyslipidemia (p < 0.001). Occupational characteristics including daily driving hours, driving distance, and travel days were not associated with any lifestyle-related diseases except for an association between short-haul and at least one disease. In conclusion, insomnia is significantly associated with increased risks of lifestyle-related diseases among male truck drivers in Japan.

Exploring the Health and Economic Burden Among Truck Drivers in Australia: A Health Economic Modelling Study.

Background The transport and logistics industry contributes to a significant proportion of the Australian economy. However, few studies have explored the economic and clinical burden attributed to poor truck driver health. We therefore estimated the work-related mortality burden among truck drivers over a 10-year period. Methods Dynamic life table modelling was used to simulate the follow-up of the Australian male working-age population (aged 15-65 years) over a 10-year period of follow-up (2021-2030). The model estimated the number of deaths occurring among the Australian working population, as well as deaths occurring for male truck drivers. Data from the Driving Health study and other published sources were used to inform work-related mortality and associated productivity loss, hospitalisations and medication costs, patient utilities and the value of statistical life year (VoSLY). All outcomes were discounted by 5% per annum. Results Over 10 years, poor truck driver health was associated with a loss of 21,173 years of life lived (discounted), or 18,294 QALYs (discounted). Healthcare costs amounted to AU$485 million (discounted) over this period. From a broader, societal perspective, a total cost of AU$2.6 billion (discounted) in lost productivity and AU$4.7 billion in lost years of life was estimated over a 10-year period. Scenario analyses supported the robustness of our findings. Conclusions The health and economic consequences of poor driver health are significant, and highlight the need for interventions to reduce the burden of work-related injury or disease for truck drivers and other transport workers.

CAR-T Cell Therapy: From the Shop to Cancer Therapy.

Cancer is a worldwide health problem. Nevertheless, new technologies in the immunotherapy field have emerged. Chimeric antigen receptor (CAR) technology is a novel biological form to treat cancer; CAR-T cell genetic engineering has positively revolutionized cancer immunotherapy. In this paper, we review the latest developments in CAR-T in cancer treatment. We present the structure of the different generations and variants of CAR-T cells including TRUCK (T cells redirected for universal cytokine killing. We explain the approaches of the CAR-T cells manufactured ex vivo and in vivo. Moreover, we describe the limitations and areas of opportunity for this immunotherapy and the current challenges of treating hematological and solid cancer using CAR-T technology as well as its constraints and engineering approaches. We summarize other immune cells that have been using CAR technology, such as natural killer (NK), macrophages (M), and dendritic cells (DC). We conclude that CAR-T cells have the potential to treat not only cancer but other chronic diseases.

The dispersion of various pollutants emitted from truck and passenger vehicles: a wind-tunnel study.

In recent years, investigation of the dispersion of exhaust gas from vehicles has received increasing attention in various studies using various approaches, including on-field measurements, experimental laboratory models, and software simulations. This study aimed to investigate the effects of changes in vehicle traffic conditions, fuel type used in an engine, and vehicle size on the emission and dispersion of gaseous pollutants from the exhaust pipe in a wind tunnel. The results showed that pollutant concentration decreases along the tailpipe centerline as the exhaust gas moves backward and the flow pattern changes significantly from 11.5 to 15 m/s. However, for the passenger car, the small recirculation region in the near-wake region at an inflow air velocity of 11.5 m/s carries away more particles compared to an incoming velocity of 15 m/s, resulting in lower gaseous concentrations in both longitudinal and transverse directions. The gaseous dispersion behind the truck and the car is wider for an inflow air velocity of 11 m/s, especially for NO, NO2, and SO2. The results also showed that the pollutant concentrations of the truck exhaust plume were higher than those of the passenger car in lower inflow air velocity in both longitudinal and transverse directions. The lower concentration of dispersed gaseous pollutants behind the passenger car model compared to the truck model may be attributed to the shape and height of the truck model, which can trap more particles behind the vehicle. Finally, the dispersion pattern of SO2 is almost identical to that of NO2, and the dispersion of the exhaust gas plume related to CO and NO pollutants is more prolonged than that of CO2 and NO2 particles along the tailpipe centerline. The findings of this study may help in estimating the concentration of pollutants along urban highways.

Factors associated with buying sex and the knowledge that condoms prevent HIV among long-distance truck drivers at Kazungula weighbridge terminal, Chobe District, Botswana.

Background: Long-distance truck drivers (LDTDs) have a higher rate of HIV infection compared to the general population. This is due to their living and working conditions which predispose them to riskier sexual behaviours. Inadequate knowledge of HIV and AIDS, coupled with risky sexual behaviours such as unprotected sex with commercial sex workers (CSWs), predisposes LDTDs to contract and propagate HIV. This study aims to determine the factors associated with buying sex and the knowledge that condoms prevent HIV transmission among long-distance truck drivers at Kazungula weighbridge terminal in the Chobe District of Botswana.Methods: A cross-sectional descriptive survey was employed and 399 LDTDs participated. A questionnaire was used to collect sociodemographic data and information on knowledge of HIV and AIDS and the sexual behaviours of the LDTDs.Results: The results reveal that more than half of the LDTDs (56.9%; n = 227) had paid for sex with CSWs at some point in their travels, and 27.1% (n = 108) reported having had unprotected sex with CSWs. The LDTDs who preferred to have sex with CSWs without a condom had about five times the odds of buying sex with CSWs than those who preferred to use a condom (AOR 4.9; 95% CI 2.85-8.46). Disliking condom use was a factor contributing to less knowledge of condom use preventing HIV among the LDTDs (AOR 0.4; CI 0.17-0.97).Conclusion: It can be concluded from the results of this study that the LDTDs engage in considerable risky sexual behaviours, and associated factors were found to be multidimensional. This population remains of concern in HIV acquisition and transmission. Therefore, there is a need for a robust public health response to deal with the problem of both new infection and re-infection with HIV in this population.

Vehicle Windshield Wiper Fluid as Potential Source of Sporadic Legionnaires' Disease in Commercial Truck Drivers.

Sporadic Legionnaires' disease is frequently detected in commercial truck drivers. We report 2 sporadic cases of this disease in Barcelona, Spain, that occurred during December 2019 and September 2020. Laboratory findings were consistent with windshield wiper fluid without added screen wash as a possible source of infection for both cases.

Bayesian criterion-based assessments of recurrent event models with applications to commercial truck driver behavior studies.

Multitype recurrent events are commonly observed in transportation studies, since commercial truck drivers may encounter different types of safety critical events (SCEs) and take different lengths of on-duty breaks in a driving shift. Bayesian nonhomogeneous Poisson process models are a flexible approach to jointly model the intensity functions of the multitype recurrent events. For evaluating and comparing these models, the deviance information criterion (DIC) and the logarithm of the pseudo-marginal likelihood (LPML) are studied and Monte Carlo methods are developed for computing these model assessment measures. We also propose a set of new concordance indices (C-indices) to evaluate various discrimination abilities of a Bayesian multitype recurrent event model. Specifically, the within-event C-index quantifies adequacy of a given model in fitting the recurrent event data for each type, the between-event C-index provides an assessment of the model fit between two types of recurrent events, and the overall C-index measures the model's discrimination ability among multiple types of recurrent events simultaneously. Moreover, we jointly model the incidence of SCEs and on-duty breaks with driving behaviors using a Bayesian Poisson process model with time-varying coefficients and time-dependent covariates. An in-depth analysis of a real dataset from the commercial truck driver naturalistic driving study is carried out to demonstrate the usefulness and applicability of the proposed methodology.

The structured health intervention for truckers (SHIFT) cluster randomised controlled trial: a mixed methods process evaluation.

BACKGROUND: This paper presents the mixed methods process evaluation of the randomised controlled trial (RCT) of the Structured Health Intervention For Truckers (SHIFT), a multi-component intervention targeting physical activity and positive lifestyle behaviours in a cohort of 382 truck drivers in the UK. The SHIFT RCT found a significant difference in daily steps between intervention and control groups at 6-months in favour of the intervention participants. METHODS: SHIFT was evaluated within a cluster-RCT and involved 25 transport sites (12 intervention and 13 control sites). Intervention components included an education session, Fitbit, text messages, and cab workout equipment. Participants completed questionnaires at baseline and 6-months follow-up. Semi-structured focus groups/interviews were conducted with drivers (n = 19) and managers (n = 18) from each site, after completion of the final follow-up health assessment (16-18 months post-randomisation). Questionnaires and interviews collected information on fidelity, dose, context, implementation, barriers, sustainability, and contamination. RESULTS: Questionnaire and interview data from intervention participants indicated favourable attitudes towards SHIFT, specifically towards the Fitbit with a high proportion of drivers reporting regularly using it (89.1%). 79.2% of intervention participants attended the education session, which was deemed useful for facilitating improvements in knowledge and behaviour change, dietary changes were predominantly recalled. Despite not being part of the intervention, participants reported that feedback from the health assessments motivated them to change aspects of their lifestyle (intervention = 91.1%, control = 67.5%). The cab workout equipment was used less and spoken unfavourably of in the interviews. The main barriers to a healthy lifestyle at work were reported as long hours and irregular shift patterns. The most suggested improvement for the intervention was more frequent contact with drivers. Managers were positive about the objectives of SHIFT, however almost all mentioned the challenges related to implementation, specifically in smaller sites. CONCLUSIONS: Overall, SHIFT was predominantly implemented as intended, with minimal discrepancies seen between the delivery and protocol. Having said this, transport sites each have distinct characteristics, which may require adaptations to individual settings to encourage participation. Managers and drivers reported enthusiasm and necessity for SHIFT to be included in future Certificate of Professional Competence training. TRIAL REGISTRATION: ISRCTN10483894 (date registered: 01/03/2017).

Upgrading Emission Standards Inadvertently Increased OH Reactivity from Light-Duty Diesel Truck Exhaust in China: Evidence from Direct LP-LIF Measurement.

Vehicular exhaust is an important source of reactive gases responsible for the formation of ozone and secondary organic aerosols (SOAs) in the atmosphere. Although significant efforts have been made to characterize the chemical compounds associated with vehicular exhaust, there is still a wealth of compounds that are unable to be detected, posing uncertainties in estimating their contribution to atmospheric reactivity. In this study, by improving laser-induced fluorescence techniques, we achieved the first-ever direct measurement of the total OH reactivity (TOR) from light-duty diesel truck (LDDT) exhaust with different emission standards. We found that the TOR from the LDDT exhaust was 80-130 times the TOR from the gasoline exhaust measured in Japan. Unexpectedly, we discovered increased TOR emissions along with upgrading emission standards, possibly as a collective result of high combustion temperature in the engine and the oxidation catalysts in the exhaust after-treatment that favor production of highly oxidized organics in the stricter emission standard. Most of these oxidized organics are unable to be speciated by routine measurements, resulting in the missing OH reactivity increasing rapidly from 1.91% for China III to 42.0% for China V LDDT. Upgrading the emission standard failed to reduce the TOR from LDDT exhaust, which may inadvertently promote the contribution of LDDT to the formation of ozone and SOA pollution in China.