US Occupational Safety Research Articles

CFD modeling of reactive species air cleaner applications in a classroom

Due to increasing concerns related to airborne virus spread indoors, more reactive species air cleaners are being utilized in classrooms. Reactive species generated by air cleaners decompose airborne pathogens chemically, decreasing the risk of infection. Due to the high reactivity of these oxidants, reactive species may be distributed nonuniformly in indoor environments, as are viral aerosols emitted by infectors. Heterogeneous distributions of reactive species may cause spatially non-uniform removal rates of viral aerosols. However, there is little information regarding spatial distributions of either reactive species or viral aerosols in ventilated classrooms. Thus, the objective of this study was to investigate spatial distributions of reactive species and infectious aerosols and to examine how operating conditions of air cleaners affect viral aerosol removal rates. A CFD model simulated the operation of a reactive species air cleaner generating hydrogen peroxide (H2O2) in a mechanically ventilated 237 m3 classroom with nine occupants. The reactive species air cleaner showed a 3–20 times higher equivalent air change rate to a HEPA filter air cleaner with the same inlet and outlet flows. During the operation of reactive species air cleaners, elevated viral aerosol concentration was confined to regions near infectors. This was due to the high reactivity of reactive species, decreasing the infection probability of receptors from 3.2 % to 0.1 % with a 1-hour exposure time. As the room average concentration of reactive species increased from 15.6 to 50.4 ppb, both below the US Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 1000 ppb, the room average infection probability decreased from 0.3 % to 0.1 %. Due to the residence times of reactive species, the location of reactive species air cleaners affected the inactivation rate of viral aerosol, resulting in a 24 % variation of concentration difference of infectious aerosol with air cleaner locations.

Contextualizing injury severity from occupational accident reports using an optimized deep learning prediction model.

This study introduced a novel approach for predicting occupational injury severity by leveraging deep learning-based text classification techniques to analyze unstructured narratives. Unlike conventional methods that rely on structured data, our approach recognizes the richness of information within injury narrative descriptions with the aim of extracting valuable insights for improved occupational injury severity assessment. Natural language processing (NLP) techniques were harnessed to preprocess the occupational injury narratives obtained from the US Occupational Safety and Health Administration (OSHA) from January 2015 to June 2023. The methodology involved meticulous preprocessing of textual narratives to standardize text and eliminate noise, followed by the innovative integration of Term Frequency-Inverse Document Frequency (TF-IDF) and Global Vector (GloVe) word embeddings for effective text representation. The proposed predictive model adopts a novel Bidirectional Long Short-Term Memory (Bi-LSTM) architecture and is further refined through model optimization, including random search hyperparameters and in-depth feature importance analysis. The optimized Bi-LSTM model has been compared and validated against other machine learning classifiers which are naïve Bayes, support vector machine, random forest, decision trees, and K-nearest neighbor. The proposed optimized Bi-LSTM models' superior predictability, boasted an accuracy of 0.95 for hospitalization and 0.98 for amputation cases with faster model processing times. Interestingly, the feature importance analysis revealed predictive keywords related to the causal factors of occupational injuries thereby providing valuable insights to enhance model interpretability. Our proposed optimized Bi-LSTM model offers safety and health practitioners an effective tool to empower workplace safety proactive measures, thereby contributing to business productivity and sustainability. This study lays the foundation for further exploration of predictive analytics in the occupational safety and health domain.

Improving Regulatory Effectiveness through Better Targeting: Evidence from OSHA

We study how a regulator can best target inspections. Our case study is a US Occupational Safety and Health Administration (OSHA) program that randomly allocated some inspections. On average, each inspection led to 2.4 (9 percent) fewer serious injuries over the next 5 years. Using new machine learning methods, we find that OSHA could have averted as much as twice as many injuries by targeting inspections to workplaces with the highest expected averted injuries and nearly as many by targeting the highest expected level of injuries. Either approach would have generated up to $850 million in social value over the decade we examine. (JEL C63, J28, J81, K32, L51)

A methodology for occupational exposure assessment of organic pollutants emitted through aerosols from recycling of e‐waste

AbstractEmission of airborne particulate matter is produced by the industrial processes of metal extraction from electronic waste (e‐waste). These aerosols can transport organic contaminants, such as polyaromatic hydrocarbons (PAHs) and polybrominated biphenyls. These pollutants are proven to have long‐term effects on workers' health. In this work, we characterize aerosol particles and dust deposited from a recycling process of printed circuit boards in a recycling plant. This study also explores the significance of the secondary aerosol sources, and their importance, as an additional burden compared to primary sources. A Scanning Mobility Particles Counter and Sizer (SMPCS) was used to measure the size distributions of ultrafine particles. A Micro‐Orifice Uniform Deposition Impactor (MOUDI) collected aerosol particle samples for chemical analysis. All plant compartments checked are subject to high particulate matter concentrations during work hours. Concentrations of organic pollutants in the machinery compartments do not pose a short or long‐term health risk according to US Occupational Safety and Health Administration (OHSA). The application of the model presented in this work revealed that the accumulation of contaminants in other compartments should be considered in an occupational exposure assessment because it can present an equally important burden to workers’ health.

Improving Hazardous Material Incident Preparedness for Emergency Medicine Physician Trainees: A Quality Improvement Project

Introduction:Hazardous materials (HazMat) training is not a requirement for accreditation of US Emergency Medicine (EM) residencies, nor for EM board certification by the American Board of Emergency Medicine (ABEM). However, the US Occupational Safety and Health Administration (OSHA) requires hospitals train all personnel expected to deal with contaminated patients. This QI project aimed to develop an EM physician-specific HazMat course and evaluate the physician comfort level with HazMat personal protective equipment (PPE) donning and doffing, triage, procedural skills, and decontamination.Method:A four-hour “HazMat for Docs” course was designed at a large urban academic trauma center and offered to second-year EM residents. Additionally, we performed a quantitative survey of a cohort of 72 current and recently graduated EM residents (classes 2019-2024), some of whom had taken the course in person. Our primary outcome was to measure improvement in comfort level with essential HazMat tasks after completing the course. Our secondary outcome was to evaluate the current or recently graduated EM physician's overall comfort levels with managing a HazMat incident, as well as HazMat skills and knowledge retention.Results:A total of 53 responses (73.6%) were obtained. 45.3% of the respondents were male and 54.7% female. 37.8% of the respondents were recent EM graduates, with 20.8% PGY-4, 13.2% PGY-3, 15.1% PGY-2, 13.2% PGY-1. 16/53 (30.2%) had prior EMS experience. EM Physicians were most comfortable with donning and doffing PPE (4.92 on a 7-point scale) and least comfortable with decontamination procedures (2.98/7). After completing the HazMat course, EM physicians increased their comfort level with HazMat decontamination procedures by 8.6% and with organizing a multi-disciplinary ED HazMat response by 10.5%.Conclusion:EM Physician comfort levels with HazMat procedures are low. Increased training aimed at improving physician knowledge, preparedness, and comfort level for such events is necessary and can be accomplished through a short course.

CO2 Pipeline risk assessment and comparison for the midcontinent United States

A comprehensive quantitative risk assessment for the construction and operation of CO2 transportation networks considered for the Midcontinent United States was conducted. The results showed risks associated with CO2 pipelines were significantly less than those of other pipeline types. The assessment used four conceptual pipelines of different lengths to discuss risks operators may see. The assessment evaluated the risk associated with construction and operation using data from the US Occupational Safety Health Administration to determine the risk of injury or death for pipeline workers and data from the US Pipeline and Hazardous Materials Safety Administration for CO2, natural gas distribution, natural gas transmission/gathering, and non-CO2 hazardous liquid pipelines to develop quantitative likelihood and severity values leading to risk values. The data for the assessment covered incidents from 2010 to 2017 for CO2 pipelines. The average risk for construction and 30 years of operation for four CO2 pipeline configurations ranging between 79 and 1,546 miles in length was found. The construction and operational risk averaged between $1,400,521 (approximately $0.02/tonne of CO2) for the shorter pipeline (79 miles) and $27,481,939 (approximately $0.10/tonne of CO2) for a longer pipeline (1,546 miles). The largest risks of fatality for CO2 pipelines comes from vehicle transport. The largest operational risk to the pipeline was due to leakage. Public pipeline opposition is also a significant risk; it was not quantified but is addressed.

Paradigm of sustainable process safety management for industrial revolution 4.0: A circular economy and sustainability perspective

AbstractThe integration of process safety management (PSM) in the transition towards a circular economy (CE) has received increased attention and consideration across a number of disciplines in the recent industrial revolution 4.0. However, questions have been raised about the conventional PSM systems lacking sustainability consideration. The purpose of this study is to introduce an emerging paradigm of sustainable process safety management (SPSM) for the industrial revolution 4.0 from the CE and sustainability point of view. By assessing the US Occupational Safety and Health Administration (OSHA) 1910 and available global PSM frameworks, this study has identified areas of improvement for corporations and presented an SPSM framework from the social, economic, and environmental perspectives in a CE. The proposed framework makes a contribution that connects the sustainability and CE perspective with the PSM and provides a basis for the future sustainable process safety guidelines for policymakers, practitioners, and industries. Additionally, this study proposed a paradigm umbrella that connects to the PSM by focusing on social, economic, and environmental pillars from sustainability that are relevant and applicable for the industrial revolution 4.0. Furthermore, it engraves a trail of imminent research possibilities in adopting an integrated sustainable PSM framework in a CE.

Evaluation of Aerosol Particle Leak and Standard Surgical Mask Fit With 3 Elastomeric Harness Designs

This comparative effectiveness study evaluates aerosol particle leak and standard surgical mask fit with 3 elastomeric harness designs tested on mannequin heads and human participants using US Occupational Safety and Health Administration N95 fit factor requirements.

Reactions

OPINION Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2021, 99 (27), p 5July 26, 2021Cite this:C&EN 99, 27, 5▸ Letters to the editor.Alien life detectorAs a 50-plus year member of the American Chemical Society, I still enjoy reading C&EN every week. Occasionally, I see an article that captures my attention, and I get an urge to convert it into poetic form. Here is one based on the report on an alien life detector by Katharine Sanderson (C&EN, May 31, 2021, page 9).Molecules can form by chance or evolution.In their complexity, each method should differ.And that was the basis for a solution.That has all the earmarks of a sniffer.So ’twas Lee Cronin’s group at Glasgow U.Who established a new recognition technique.And, let us say, that between me and you.It is one that is truly unique.A complexity score algorithm they first devised.For any given molecular species.And a Molecular Assembly number that is based on size.Became the centerpiece of their new thesis.For big biological molecules have many bonds.Compared with those that are inorganic.And a large MA number, therefore, corresponds.To those that are bio-organic.Now, Tandem Mass Spec. is the method they use.And the experimental variable is its second stage.If there is a large number of peaks they will choose.To say it must come from a biological cage.They have tested the theory on samples galore.Both bio-organic and inorganic, too.And above an MA threshold was an evolutionary score.Which gave good correlation, it is true.Much more work, though, has yet to be done.To increase sensitivity at low concentration.For there are few molecules between here and the sun.Or in outer space since the act of creation.So, if the MA algorithm can be retooled.And applied to infrared spectroscopy data.Then extrasolar planetary molecules.Could be identified as Alien Life matter!Andrew Roxburgh McGhieWilmington, DelawareLisa JonesThank you for your recent story on professor Lisa Jones’s decision to withdraw her name from consideration for a faculty position at the University of North Carolina at Chapel Hill after the disturbing action by the board in denying tenure to Pulitzer Prize–winning journalist Nikole Hannah-Jones (C&EN, June 14, 2021, page 7). It is inspiring to see professor Jones put her commitment to the values of diversity, equity, and inclusion into action, calling out this apparent example of racial bias. C&EN writer Melba Newsome did a great job in reporting the story, adding comments from chemistry faculty members at UNC who shared their concerns about the impact of the Hannah-Jones tenure case on their efforts to recruit faculty of color.Randy HealdFort Scott, KansasOSHA and chemical safetyThank you for the interestingarticle regarding the US Occupational Safety and Health Administration (OSHA) and comments by David Michaels about the organization that he once headed (C&EN, June 28, 2021, page 26). The formation of OSHA in 1970 was an important turning point in worker health and safety. I enrolled in my chemistry major in 1952 at what is now the University of Massachusetts Lowell. Laboratory ventilation back then was a joke. We were exposed to asbestos, mercury, benzene, and a great assortment of chemicals that today are off limits in undergraduate labs. I am happy to still be alive!My first real exposure to lab safety was as an employee of DuPont in Wilmington, Delaware. Safety was stressed from day 1, including group safety meetings. When I eventually left to join the faculty at the University of Wisconsin–Eau Claire, I was given the job as chair of the chemistry department’s Safety Committee. That was quite a challenge for academic chemists with no industrial backgrounds. Luckily I survived to enjoy retirement!Allen A. DenioNewark, Delaware. CorrectionsJuly 5/12, 2021, page 20: The feature story on nitrous oxide incorrectly says that Ascend Performance Materials uses just selective catalytic reduction to destroy nitrogen oxides at its adipic acid plant near Pensacola, Florida. It uses both selective catalytic reduction and thermal reduction.July 5/12, 2021, page 26: The cover story about developing new American Sign Language signs for scientific terms has the wrong date of the photograph of Daniel Lundberg. It was taken in 2015, not 2019. The article also has an incorrect title for Paula Christopher. Christopher is a program manager at the Office of Diversity, Equity, Inclusion, and Respect at the American Chemical Society, not a program manager of diversity planning and strategy.

Thermal Condition and Air Quality Investigation in Commercial Airliner Cabins

Cabin air quality and thermal conditions have a direct impact on passenger and flight crew’s health and comfort. In this study, in-cabin thermal environment and particulate matter (PM) exposures were investigated in four China domestic flights. The mean and standard deviation of the in-cabin carbon dioxide (CO2) concentrations in two tested flights are 1440 ± 111 ppm. The measured maximum in-cabin carbon monoxide (CO) concentration is 1.2 ppm, which is under the US Occupational Safety and Health Administration (OSHA) permissible exposure limit of 10 ppm. The tested relative humidity ranges from 13.8% to 67.0% with an average of 31.7%. The cabin pressure change rates at the end of the climbing stages and the beginning of the descending stages are close to 10 hPa·min−1, which might induce the uncomfortable feeling of passengers and crew members. PM mass concentrations were measured on four flights. The results show that PM concentrations decreased after the aircraft cabin door closed and were affected by severe turbulences. The highest in-cabin PM concentrations were observed in the oldest aircraft with an age of 13.2 years, and the waiting phase in this aircraft generated the highest exposures.

Nothing lasts forever: Items missing from your preventative maintenance system

AbstractDue to the number of serious Process Safety incidents that have occurred from the implementation of the Process Safety Management Standard, US Occupational Safety and Health Administration has implemented National Emphasis Programs to audit process safety compliance at refineries and chemical processing plants. Both the Refinery and the Chemical National Emphasis programs identified Mechanical Integrity as the element with the largest number of compliance gaps. An overview of the techniques used to identify the scope of an Asset Integrity System will be provided. Learning from incidents, including outside the Chemical Processing Industry, that have occurred will be reviewed to illustrate the importance of smaller, often overlooked, items that became root causes of incidents. The goal of this paper is to provide the reader with guidance on identification, determination of inspection frequency, documentation and deficiency resolution of critical equipment that not only satisfies the regulatory requirements but also includes all items, including small, often overlooked items.

Assessing the effect of beard hair lengths on face masks used as personal protective equipment during the COVID-19 pandemic.

BackgroundGlobally, a large percentage of men keep a beard at least occasionally. Workplace regulations prohibit beards with N95 respirators, but there is little information on the effect of beards with face masks worn by the public for protection against SARS-CoV-2.Methods and findingsWe examined the fitted filtration efficiency (FFE) of five commonly worn protective face masks as a function of beard length following the US Occupational Safety and Health Administration Quantitative Fit Test: N95 (respirator), KF94 and KN95, surgical/procedure, and cloth masks. A comparison using N95 respirators was carried out in shaven and bearded men. A detailed examination was conducted for beard lengths between 0 and 10 mm (0.5 mm increments). The effect of an exercise band covering the beard on FFE was also tested. Although N95 respirators showed considerable variability among bearded men, they had the highest FFE for beard lengths up to 10 mm. KF94 and KN95 masks lost up to 40% of their FFE. Procedure and cotton masks had poor performance even on bare skin (10–30% FFE) that did not change appreciably with beard length. Marked performance improvements were observed with an exercise band worn over the beard.ConclusionsThough variable, N95 respirators offer the best respiratory protection for bearded men. While KF94 and KN95 FFE is compromised considerably by increasing beard length, they proved better options than procedure and cotton face masks. A simple exercise band improves FFE for face masks commonly used by bearded men during the COVID-19 pandemic.

Evaluation of hydrogen peroxide and ozone residue levels on N95 masks following chemical decontamination

BackgroundHydrogen peroxide and ozone have been used as chemical decontamination agents for N95 masks during supply shortages. If left behind on the masks, the residues of both chemicals represent a potential health hazard by skin contact and respiratory exposure.AimCharacterization of hydrogen peroxide and ozone residues on mask surfaces after chemical decontamination.MethodsVarious N95 masks were decontaminated using two commercial systems employing either aerosol spray or vaporization of hydrogen peroxide in the presence of ozone. Following the decontamination, the masks were aired out to eliminate moisture and potential chemical residues. The residual hydrogen peroxide and ozone were monitored in the gas phase above the mask surface, and hydrogen peroxide residue directly on mask surfaces using a colorimetric assay.FindingsAfter decontamination, hydrogen peroxide and ozone were detectable in the gas phase in the vicinity of masks even after 5 h of aeration. Hydrogen peroxide was also detected on all studied masks, and levels up to 56 mg per mask were observed after 0.5 h of aeration. All residues gradually decreased with aeration, likely due to decomposition and vaporization.ConclusionHydrogen peroxide and ozone were present on N95 masks after decontamination. With appropriate aeration, the gaseous residue levels in the vicinity of the masks decreased to permissible levels as defined by the US Occupational Safety and Health Administration. Reliable assays to monitor these residues are necessary to ensure the safety of the mask users.

Migrant Worker Safety, Occupational Health Equity, and Labor Trafficking

The US Occupational Safety and Health (OSH) Act of 1970 has helped reduce workplace fatalities and injuries. However, fatalities in migrant workers have disproportionately increased. This editorial discusses 1) how inequitably beneficial this health law has been for migrant workers 2) the unique occupational health risks labor trafficked migrants face 3) the role public health can play in addressing the needs of labor-trafficked migrant workers. Physical and emotional hazards, intrinsic to the notably dangerous occupations, are disproportionately felt by migrant workers due to systemic barriers including but not limited to economic hardship and coercion, language barriers, fear of legal repercussions, lack of protective equipment, racism and xenophobia. Labor trafficked workers also face additional significant occupational health risks and barriers to accessing medical care. Our recommendations to protect labor trafficked migrant workers involve improvements in research, policy, medical education, and health care delivery

Evaluation of Cloth Masks and Modified Procedure Masks as Personal Protective Equipment for the Public During the COVID-19 Pandemic

During the coronavirus disease 2019 (COVID-19) pandemic, the general public has been advised to wear masks or improvised face coverings to limit transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, there has been considerable confusion and disagreement regarding the degree to which masks protect the wearer from airborne particles. To evaluate the fitted filtration efficiency (FFE) of various consumer-grade and improvised face masks, as well as several popular modifications of medical procedure masks that are intended to improve mask fit or comfort. For this study conducted in a research laboratory between June and August 2020, 7 consumer-grade masks and 5 medical procedure mask modifications were fitted on an adult male volunteer, and FFE measurements were collected during a series of repeated movements of the torso, head, and facial muscles as outlined by the US Occupational Safety and Health Administration Quantitative Fit Testing Protocol. The consumer-grade masks tested included (1) a 2-layer nylon mask with ear loops that was tested with an optional aluminum nose bridge and filter insert in place, (2) a cotton bandana folded diagonally once (ie, "bandit" style) or in a (3) multilayer rectangle according to the instructions presented by the US Surgeon General, (4) a single-layer polyester/nylon mask with ties, (5) a polypropylene mask with fixed ear loops, (6) a single-layer polyester gaiter/neck cover balaclava bandana, and (7) a 3-layer cotton mask with ear loops. Medical procedure mask modifications included (1) tying the mask's ear loops and tucking in the side pleats, (2) fastening ear loops behind the head with 3-dimensional-printed ear guards, (3) fastening ear loops behind the head with a claw-type hair clip, (4) enhancing the mask/face seal with rubber bands over the mask, and (5) enhancing the mask/face seal with a band of nylon hosiery over the fitted mask. The primary study outcome was the measured FFE of common consumer-grade and improvised face masks, as well as several popular modifications of medical procedure masks. The mean (SD) FFE of consumer grade masks tested on 1 adult male with no beard ranged from 79.0% (4.3%) to 26.5% (10.5%), with the 2-layer nylon mask having the highest FFE. Unmodified medical procedure masks with ear loops had a mean (SD) FFE of 38.5% (11.2%). All modifications evaluated in this study increased procedure mask FFE (range [SD], 60.3% [11.1%] to 80.2% [3.1%]), with a nylon hosiery sleeve placed over the procedure mask producing the greatest improvement. While modifications to improve medical procedure mask fit can enhance the filtering capability and reduce inhalation of airborne particles, this study demonstrates that the FFEs of consumer-grade masks available to the public are, in many cases, nearly equivalent to or better than their non-N95 respirator medical mask counterparts.

Current understanding and future directions for an occupational infectious disease standard

The coronavirus disease 2019 pandemic has demonstrated a need for an infectious disease standard that will promote a safe and healthy work environment and assure business continuity. The current pandemic has revealed gaps in workplace preparedness and employee protections to microbial exposures. Federal and state government agencies have responded by providing interim guidelines and stop-gap measures that continue to evolve and vary in approach and required controls. This interim and inconsistent approach has resulted in confusion on the part of businesses as they work toward reopening during the pandemic and uncertainty as to the efficacy of required or suggested controls. Moving forward, the US Occupational Safety and Health Administration, with guidance from the US National Institute for Occupational Safety and Health, should establish consistent and effective strategies through a nationwide standard to address the potential microbial exposures in the workplace. Such a standard will require effective worker protections from infectious diseases and assure business continuity.

Decontamination and Reuse of N95 Respirators with Hydrogen Peroxide Vapor to Address Worldwide Personal Protective Equipment Shortages During the SARS-CoV-2 (COVID-19) Pandemic.

Decontamination and Reuse of N95 Respirators with Hydrogen Peroxide Vapor to Address Worldwide Personal Protective Equipment Shortages During the SARS-CoV-2 (COVID-19) Pandemic.

Extraction and analysis of construction safety hazard factors from open data

Construction is one of the most injury prone industries worldwide. Concerns of health and safety of the employees in construction sites have been a vastly discussed topic for decades. In many countries, companies are required to report safety incidents by using catastrophe investigating report in their workplaces to relevant authorities whereby such data is made publicly available under the open data policy. These open datasets may be well structured or may require further preparation in order to be usable. Some datasets are in the form of reports, which require qualitative, textual analysis to extract insightful information. The purpose of this study is to extract safety hazard factors from an open dataset obtained from the US Occupational Health and Safety Administration, and to further analyse such factors using statistical analysis techniques. For each reported case, text analysis was carried out with the narrative data field describing the circumstances leading to safety incidents to extract safety hazard factors. These hazard factors were categorized into human factors, technical factors, external environmental factors, organizational factors and other factors. The results showed that hazards related to human factors are most common. Descriptive statistics also showed that the most frequent nature of accident was fractures and most frequently occurring accident event was falls to the lower levels. Such information can help to provide insights into the accidents occurred and how relevant authorities may devise strategies to improve construction site safety.

Occupational Co-exposures to Multiple Chemical Agents from Workplace Measurements by the US Occupational Safety and Health Administration.

The occupational environment represents an important source of exposures to multiplehazards for workers' health. Although it is recognized that mixtures of agents may have differenteffects on health compared to their individual effects, studies generally focus on the assessment ofindividual exposures. Our objective was to identify occupational co-exposures occurring in the United States using the multi-industry occupational exposure databank of the Occupational Safety and Health Administration (OSHA). Using OSHA's Integrated Management Information System (IMIS), measurement data from workplace inspections occurring from 1979 to 2015 were examined. We defined a workplace situation (WS) by grouping measurements that occurred within a company, within the same occupation (i.e. job title) within 1 year. All agents present in each WS were listed and the resulting databank was analyzed with the Spectrosome approach, a methodology inspired by network science, to determine global patterns of co-exposures. The presence of an agent in a WS was defined either as detected, or measured above 20% of a relevant occupational exposure limit (OEL). Among the 334 648 detected exposure measurements of 105 distinct agents collected from 14 513 US companies, we identified 125 551 WSs, with 31% involving co-exposure. Fifty-eight agents were detected with others in >50% of WSs, 29 with a proportion >80%. Two clusters were highlighted, one for solvents and one for metals. Toluene, xylene, acetone, hexone, 2-butanone, and N-butyl acetate formed the basis of the solvent cluster. The main agents of the metal cluster were zinc, iron, lead, copper, manganese, nickel, cadmium, and chromium. 68 556 WS were included in the analyses based on levels of exposure above 20% of their OEL, with 12.4% of co-exposure. In this analysis, while the metal cluster remained, only the combinations of toluene with xylene or 2-butanone were frequently observed among solvents. An online web application allows the examination of industry specific patterns. We identified frequent co-exposure situations in the IMIS databank. Using the spectrome approach, we revealed global combination patterns and the agents most often implicated. Future work should endeavor to explore the toxicological effects of prevalent combinations of exposures on workers' health to prioritize research and prevention efforts.

Improving Regulatory Effectiveness Through Better Targeting: Evidence from OSHA

We study how a regulator can best target inspections. Our case study is a US Occupational Safety and Health Administration (OSHA) program that randomly allocated some inspections. On average, each inspection averted 2.4 serious injuries (9%) over the next five years. We use new machine learning methods to estimate the effects of counterfactual targeting rules. OSHA could have averted over twice as many injuries by targeting the highest expected averted injuries and nearly as many by targeting the highest expected level of injuries. Either approach would have generated over $1 billion in social value over the decade we examine.