Observational study on occupational exposure of dairy farmers to formaldehyde.

OBJECTIVES: To provide insights into exposure of Dutch dairy farmers to formaldehyde derived from formalin footbaths used for cows. Dutch safety norms are set at a limit of 0.122 ppm during an 8-hour time-weighted average (TWA) and 0.407 ppm for a 15-min TWA. METHODS: At 20 farms formaldehyde air concentrations were determined using stationary active air sampling with impingers next to the footbath and in the milking parlour during footbath usage. Formalin footbath concentrations were tested and meteorological conditions were collected using a climate monitor to assess associations with formaldehyde concentrations. A structured interview inquired on potential exposure routes and exposure duration. RESULTS: Formaldehyde concentrations next to the footbath ranged from <0.003 to 0.316 ppm, with seven measurements exceeding the 8-hour TWA threshold. None of the measurements exceeded the 15-min TWA threshold at either location. Formaldehyde air concentrations in the milking parlour were generally lower, yet at two farms exceeded the 8-hour TWA limit during sampling. Self-reported exposure time of the dairy farmers to the formalin footbath never exceeded 15 min. Although due to the small sample size, no significant associations between most predictor variables and formaldehyde levels in the air were found, the direction of effects were as expected. CONCLUSIONS: The exposure of Dutch dairy farmers presumably falls within the established safety norms. Nonetheless, substantial levels of formaldehyde could be detected. This study further emphasises the importance of substitution of formalin in dairy practice and the relevance of informing dairy farmers on proper handling of formalin to reduce exposure.

A case of syncope in a villager with hypertrophic cardiomyopathy after hydrogen sulfide exposure by an unauthorized discharge of wastewater.

Background: Hydrogen sulfide is a toxic substance that humans can be exposed to occupationally, and cases of hydrogen sulfide poisoning of workers in industrial sites are commonly reported. However, there have been no cases of poisoning of the public due to an unauthorized discharge of wastewater, so it is important to describe this incident. Case presentation: In a small village in Jeollanam-do, Republic of Korea, accounts of a terrible stench had been reported. A 26-year-old man who lived and worked in a foul-smelling area was taken to the emergency room with a headache, dizziness, nausea, and repeated syncope. A subsequent police and Ministry of Environment investigation determined that the cause of the stench was the unauthorized discharge of 9 tons of wastewater containing hydrogen sulfide through a stormwater pipe while the villagers were sleeping. The patient had no previous medical history or experience of symptoms. Leukocytes and cardiac markers were elevated, an electrocardiogram indicated biatrial enlargement, left ventricular hypertrophy, and corrected QT interval prolongation. Myocardial hypertrophy was detected on a chest computed tomography scan, and hypertrophic cardiomyopathy was confirmed on echocardiography. After hospitalization, cardiac marker concentrations declined, symptoms improved, and the patient was discharged after 7 days of hospitalization. There was no recurrence of symptoms after discharge. Conclusions: We suspect that previously unrecognized heart disease manifested or was aggravated in this patient due to exposure to hydrogen sulfide. Attention should be paid to the possibility of unauthorized discharge of hydrogen sulfide, etc., in occasional local incidents and damage to public health. In the event of such an accident, it is necessary to have government guidelines in place to investigate health impact and follow-up clinical management of exposed residents.

Length of employment in workplaces handling hazardous chemicals and risk of cancer among Japanese men.

OBJECTIVES: In Japan, the risk of developing cancer among workers employed in workplaces where chemical substances are handled is unclear. This study aimed to assess the association between cancer risk and employment in workplaces handling hazardous chemicals. METHODS: The Inpatient Clinico-Occupational Survey of the Rosai Hospital Group data of 120 278 male patients with incident cancer and 217 605 hospital controls matched for 5-year age group, hospital (34 hospitals) and year of admission (2005-2019) were analysed. Cancer risk in relation to lifetime employment in workplaces using regulated chemicals was assessed while controlling for age, region and year of diagnosis, smoking, alcohol consumption and occupation. Further analysis stratified by smoking history was performed to examine interaction effects. RESULTS: In the longest group of employment in tertiles, ORs were increased for all cancers (OR=1.13; 95% CI: 1.07 to 1.19) and lung (OR=1.82; 95% CI: 1.56 to 2.13), oesophageal (OR=1.73; 95% CI: 1.18 to 2.55), pancreatic (OR=2.03; 95% CI: 1.40 to 2.94) and bladder (OR=1.40; 95% CI: 1.12 to 1.74) cancers. Employment of 1+ years was associated with risk for lung cancer; 11+ years for pancreatic and bladder cancers; and 21+ years for all cancers and oesophageal cancer. These positive relationships were particularly obvious among patients with a history of smoking; however, no significant interaction between smoking and length of employment was observed. CONCLUSIONS: There is a high risk of cancer among workers, especially smokers, employed in workplaces handling regulated chemicals in Japan. Thus, future measures for chemical management in workplaces are needed to prevent avoidable cancers.

Occupational risk factors and exposure-response relationships for airway disease among health workers exposed to cleaning agents in tertiary hospitals.

OBJECTIVES: This study investigated occupational risk factors and exposure-response relationships for airway disease among health workers (HWs) exposed to cleaning agents in two tertiary hospitals in South Africa and Tanzania. METHODS: In this cross-sectional study, 697 participants completed questionnaire interviews while 654 underwent fractional exhaled nitric oxide (FeNO) testing. Asthma Symptom Score (ASS) was computed based on the sum of answers to five questions on asthma-related symptoms in the past 12 months. For exposure-response analyses, cleaning agent-related self-reported exposure variables were categorised into three levels (cleaning product not used; use of a cleaning product for up to 99 min per week and use of a cleaning product for ≥100 min per week). RESULTS: Asthma-related outcomes (ASS and FeNO) demonstrated positive associations with medical instrument cleaning agents (orthophthalaldehyde and enzymatic cleaners) and tasks (instruments precleaning and changing sterilisation solutions) as well as patient care activities (disinfection prior to procedures and disinfecting wounds). A particularly pronounced dose-response relationship was observed between work-related ocular-nasal symptoms and medical instrument cleaning agents (orthophthalaldehyde, glutaraldehyde, enzymatic cleaners, alcohols and bleach) (OR range: 2.37-4.56) and tasks (OR range: 2.92-4.44). A strong association was also observed between ASS and use of sprays for fixed surface cleaning (mean ratio 2.81; 95% CI 1.41 to 5.59). CONCLUSIONS: Specific agents for medical instrument disinfection for example, orthophthalaldehyde and enzymatic cleaners, patient care activities and use of sprays are important occupational risk factors for airway disease among HWs.

The Effect of Prior Mental Health on Persistent Physical Symptoms after Exposure to a Chemical Disaster.

A styrene monomer (SM) oil vapor leak occurred at a chemical plant in Seosan, South Korea on 17 May 2019. A bad odor developed, and many residents complained of various symptoms and visited nearby medical institutions. We analyzed the demographic and clinical characteristics of patients treated at local hospitals and clinics for symptoms related to SM exposure, and identified factors affecting symptom persistence in any organ. Data were collected by the main Seosan office, and 1201 (33.0%) subjects agreed to participate in this study. We used the Assessment of Chemical Exposure toolkit of the Agency for Toxic Substances and Disease Registry. Logistic regression was performed to determine whether mental health symptoms prior to the accident were risk factors for symptom persistence. The strongest risk factor for persistence of at least one symptom in any organ was a preexisting mental health symptom (odds ratio [OR] = 5.47, 95% confidence interval [CI]: 2.57-11.65). Persistent symptoms of the nervous (OR = 1.54), musculoskeletal (OR = 1.92), and gastrointestinal (OR = 1.45) systems were observed. Prior mental health symptoms are risk factors for persistent physical symptoms after a chemical disaster. After a disaster, management of individuals with preaccident mental symptoms or disease is needed.

Exposure to an accidental trichlorosilane spill: three case reports.

Chlorosilane is a hazardous chemical compound which is used as a raw material in the production of silicone. Despite strict restrictions, accidental spillage of chlorosilane is often reported. However, human exposure was rarely reported in the past decades and the effect on humans is barely known. We report cases of human exposure to an accidental trichlorosilane spill. Three middle aged male industrial workers visited our emergency department after exposure to trichlorosilane. They presented with shortness of breath and burns on multiple sites. Chest radiograph and laboratory studies were performed. None of the reports showed serious results and were discharged after conservative management.

Occupational exposures to pesticides and other chemicals: a New Zealand motor neuron disease case-control study.

OBJECTIVES: To assess associations between occupational exposures to pesticides and other chemicals and motor neuron disease (MND). METHODS: A population-based case-control study that included 319 MND cases (64% male/36% female) recruited through the New Zealand MND Association complemented with hospital discharge data, and 604 controls identified from the Electoral Roll. For each job held, a questionnaire collected information on 11 exposure categories (dust, fibres, tobacco smoke, fumes, gas, fumigants, oils/solvents, acids/alkalis, pesticides, other chemicals and animals/animal products). ORs were estimated using logistic regression adjusting for age, sex, ethnicity, socioeconomic status, education, smoking, alcohol consumption, physical activities, head/spine injury and other occupational exposures. RESULTS: Two exposure categories were associated with increased MND risks: pesticides (OR 1.70, 95% CI 1.17 to 2.48) and fumigants (OR 3.98, 95% CI 1.81 to 8.76), with risks increasing with longer exposure duration (p<0.01). Associations were also observed for: methyl bromide (OR 5.28, 95% CI 1.63 to 17.15), organochlorine insecticides (OR 3.28, 95% CI 1.18 to 9.07), organophosphate insecticides (OR 3.11, 95% CI 1.40 to 6.94), pyrethroid insecticides (OR 6.38, 95% CI 1.13 to 35.96), inorganic (copper) fungicides (OR 4.66, 95% CI 1.53 to 14.19), petrol/diesel fuel (OR 2.24, 95% CI 1.27 to 3.93) and unspecified solvents (OR 1.91, 95% CI 1.22 to 2.99). In women, exposure to textile fibres (OR 2.49, 95% CI 1.13 to 5.50), disinfectants (OR 9.66, 95% CI 1.29 to 72.44) and cleaning products (OR 3.53, 95% CI 1.64 to 7.59) were also associated with MND; this was not observed in men (OR 0.80, 95% CI 0.44 to 1.48; OR 0.72, 95% CI 0.29 to 1.84; OR 0.57, 95% CI 0.21 to 1.56, respectively). CONCLUSIONS: This study adds to the evidence that pesticides, especially insecticides, fungicides, and fumigants, are risk factors for MND.

Insufficient respiratory hazard identification in the safety data sheets for cleaning and disinfection products used in healthcare organisations across England and Wales.

BACKGROUND: Exposure to cleaning and disinfection products has been associated with respiratory disorders such as asthma in cleaning and healthcare workers. Safety data sheets (SDSs) provide information on hazardous chemicals that are present in products to help users with risk assessment and implement appropriate control measures. However, they have potential limitations in identifying respiratory hazards due to a lack of regulatory test methods for respiratory sensitisation and irritation of chemicals. METHODS: SDSs were first used to identify chemicals on the database as respiratory sensitisers and irritants. A quantitative structure-activity relationship (QSAR) model and an asthmagen list established by the Association of Occupational and Environmental Clinics (AOEC) were used to identify potential respiratory sensitisers and irritants (by the AOEC list only) in the cleaning and disinfection products. RESULTS: From a total of 459 cleaning and disinfection products used in healthcare organisations across England and Wales, 35 respiratory sensitisers not labelled as such on the SDS were identified by QSAR or AOEC. Only 2% of cleaning and disinfection products contained at least one respiratory sensitiser as identified by their SDSs; this was increased to 37.7% of products when the QSAR or the AOEC list was used. CONCLUSIONS: A significantly higher proportion of cleaning products contain respiratory hazardous chemicals, particularly respiratory sensitisers than would be expected from the information provided by SDSs alone. Cleaners and healthcare workers may, therefore, be insufficiently protected.

Application of calcium nebulization for mass exposure to an accidental hydrofluoric acid spill.

PURPOSE: To determine the long-term prevalence and characteristics of acute hydrofluoric acid (HF) exposure in 2223 patients during the first 30 months after a mass-casualty exposure, and to confirm the antidotal effect of nebulized calcium on inhalation burns caused by HF. METHODS: This observational cohort study included patients after an HF spill in the Republic of Korea on September 27, 2012; registered patients were followed until April 2015. We assessed toxic effects, distance from spill, degree of acute poisoning, and the effect of nebulized calcium in HF-exposed individuals. RESULTS: Overall, 2223 patients received emergency management or antidote therapy for 20 days. Seventy-four of 134 patients with dermal toxicity received calcium-lidocaine gel, and 368 individuals with bronchial irritation signs received calcium gluconate via nebulizer nCG. A total 377 ampoules 786 g of calcium gluconate were used in the nCG formulation. Calcium administration did not cause adverse reactions during the observation period. Long-term cohort observation showed that 120 patients (120/2233, 5.4%) returned to medical facilities for management of HF-related symptoms within 1 month; 18 persons (18/1660, 1.1%) returned 1-3 months later with chronic cough and respiratory symptoms; and 3 patients (3/1660, 0.2%) underwent medical treatment due to upper-airway toxic symptoms more than 2 years after HF exposure. CONCLUSION: Respiratory toxicity after mass exposure to an HF spill was successfully treated by calcium nebulizer. Based on our experience, detoxification processes and the amounts of antidote stocked are important when planning for future chemical disasters at the community level.

Characteristics of mass casualty chemical incidents: a case series

OBJECTIVE: The aim of this study was to evaluate the characteristics of the emergency medical services (EMS) response and clinical information on mass casualty chemical incidents in Korea. METHODS: This retrospective observational study analyzed the integrated data of the EMS rescue records and EMS-treated severe trauma registry from January 2012 to December 2013. Two databases were integrated using the unique accident identification number. Chemical incidents were defined by an in-depth review of the EMS rescue records according to a previous study. Mass casualty incidents were defined as more than 6 injured individuals. The rescue, EMS, and hospital variables of mass casualty chemical incidents were analyzed. RESULTS: A total of 8 mass casualty chemical incidents and 73 patients were included. The mean responded rescue vehicles and EMS vehicles were 2.4 and 3.5, respectively. The 4 incidents were an oil spill due to traffic accidents and most patients suffered minor trauma. A carbon monoxide leak caused the largest number of patients (23 people). The explosion caused by flammable polyethylene leaks showed the highest severity. In that explosion, the mortality rate was 40% and 8 patients had a disability at discharge. CONCLUSION: This study evaluated the characteristics of the EMS response and clinical information on mass casualty chemical incidents in Korea.

Medical Response to a Vinyl Chloride Release From a Train Derailment: New Jersey, 2012.

OBJECTIVE: The objective of this investigation was to examine the health impact of and medical response to a mass casualty chemical incident caused by a vinyl chloride release. METHODS: Key staff at area hospitals were interviewed about communication during the response, the number of patients treated and care required, and lessons learned. Clinical information related to the incident and medical history were abstracted from hospital charts. RESULTS: Hospital interviews identified a desire for more thorough and timely incident-specific information and an under-utilization of regionally available resources. Two hundred fifty-six hospital visits (96.2%) were at the facility closest to the site of the derailment. Of 237 initial visits at which the patient was examined by a physician, 231 patients (97.5%) were treated in the emergency department (ED) and 6 patients (2.5%) were admitted; 5 admitted patients (83.3%) had preexisting medical conditions. Thirteen of 14 asymptomatic ED patients were children under the age of 10 years. One hundred forty-five patients (62.8%) discharged from the ED were diagnosed solely with exposure to vinyl chloride. CONCLUSIONS: Continuous emergency response planning might facilitate communication and better distribution of patient surge across hospitals. Individuals with multiple medical conditions and parents and caretakers of children may serve as target groups for risk communication following acute chemical releases. (Disaster Med Public Health Preparedness. 2017;11:538-544).

Characteristics of Emergency Medical Service Provider Responded Chemical, Biological, Radiological, and Nuclear Incidents: Pilot Analysis of National Emergency Medical Service Rescue Records

PURPOSE: The aim of this study was to evaluate the characteristics of Emergency Medical Service (EMS) provider responded chemical, biological, radiological, and nuclear (CBRN) incidents in Korea. METHODS: Nationwide EMS rescue records from Jan 2012 to Dec 2014 were analyzed. All EMS rescue records were integrated according to the unique accident ID. Cases related to animal rescue, hive removal, and suicide-related were excluded. CBRN-associated keywords were extracted by literature review and pilot survey. In-depth review of cases containing CBRN-associated keywords in the activity summary were conducted by trained emergency medical technicians, and predefined information was abstracted. Descriptive analyses were performed to characterize the EMS provider responded CBRN incidents. RESULTS: A total of 1,571,293 cases were included, and 1,335,205 cases had a unique accident ID; 515,417 cases were excluded because of their association with animal rescue, hive removal, and suicide attempts; 19,663 cases contained CBRN-associated keywords in the activity summary, and in-depth review identified 1,862 cases as CBRN incidents. Among them 1,856 cases were chemical incidents, and 6 cases were radiological incidents; 144 cases were resulted to victims. In chemical incidents, ammonia, hydrogen chloride, sulfuric acid, hydrogen fluoride, and nitric acid were the top 5 toxic substances. In chemical incidents with victims, the proportion of explosion/implosion, and suffocation in sealed space was more prevalent than chemical incidents without victims. Median scene time of all CBRN incidents was 41 minutes (interquartile range 18.0-57.0). CONCLUSION: We evaluated the characteristics of CBRN incidents responded by EMS in Korea.

Physician Emergency Preparedness: A National Poll of Physicians.

OBJECTIVE: To provide a more comprehensive view than previously available of US physician preparedness for public health emergencies, this study examined physicians' assessments of their preparedness, training, participation in institutional activities, information practices, and experiences with patient education. Four kinds of public health emergencies were considered: natural disasters, major airborne infections, major foodborne illness outbreaks, and chemical, biological, radiological, nuclear, or explosives (CBRNE) incidents. METHODS: Between October 19, 2011, and January 11, 2012, researchers conducted a national poll among 1603 practicing physicians in a range of specialties in hospital and nonhospital settings. RESULTS: More than one-half of physicians felt prepared to handle a natural disaster, a major outbreak of an airborne infection, or a major foodborne illness outbreak, whereas one-third (34%) felt prepared to handle a CBRNE incident. About one-half of physicians (55%) had participated in training or a conference related to emergencies in the past 2 years. Sizable fractions of physicians were unaware of emergency response tools in their care setting. For example, nearly one-half in hospitals (44%) did not know whether their care setting had an emergency response plan, and less than one-quarter had participated in a drill using such a plan in the past 2 years. Less than one-third (31%) of physicians had signed up to receive alerts in the case of future emergencies. One in 10 reported sharing emergency information with patients at least "sometimes." CONCLUSIONS: Significant gaps remain in physician preparedness for public health emergencies, as well as in related training and participation in institutional activities. New efforts, with a focus on possible collaborations between public health institutions and health system leaders combined with effective use of online resources, are needed to bring more physicians on board and to develop relevant and useful key tools. New approaches, including those that rely on different types of care providers, may be needed to enhance patient education regarding emergency preparedness.

Medical Surge Capacity in Atlanta-Area Hospitals in Response to Tanker Truck Chemical Releases.

OBJECTIVE: We designed and conducted a regional full-scale exercise in 2007 to test the ability of Atlanta-area hospitals and community partners to respond to a terrorist attack involving the coordinated release of 2 dangerous chemicals (toluene diisocyanate and parathion) that were being transported through the area by tanker truck. METHODS: The exercise was designed to facilitate the activation of hospital emergency response plans and to test applicable triage, decontamination, and communications protocols. Plume modeling was conducted by using the Defense Threat Reduction Agency's (DTRA) Hazard Prediction and Assessment Capability (HPAC) V4 program. The scenario went through multiple iterations as exercise planners sought to reduce total injuries to a manageable, but stressful, level for Atlanta's health care infrastructure. RESULTS: Atlanta-area hospitals rapidly performed multiple casualty triage and were able to take in a surge of victims from the simulated attack. However, health care facilities were reticent to push the perceived manageable numbers of victims, and scenarios were modified significantly to lower the magnitude of the simulated attack. Additional coordination with community response partners and incident command training is recommended. Security at health care facilities and decontamination of arriving victims are two areas that will require continued review. CONCLUSION: Atlanta-area hospitals participated in an innovative regional exercise that pushed facilities beyond traditional scopes of practice and brought together numerous health care community response partners. Using lessons learned from this exercise coupled with subsequent real-world events and training exercises, participants have significantly enhanced preparedness levels and increased the metropolitan region's medical surge capacity in the case of a multiple casualty disaster.

A Clinical Analysis of Patients Who Visited Emergency Department due to Chemical Incident Occurred at Industrial Place: A Retrospective Study

PURPOSE: The purpose of this study is to understand what kinds of chemical substances have been used annually and to investigate incidents that occurred due to chemical hazard release and to analyze statistically clinically chemical injury patients who visited one regional emergency medical center in Gumi city with documented references review. METHODS: Annual chemical waste emission quantity (Kg/Year) (Cwep) was reproduced using national web site data governed by the Ministry of Environment and 5 years (from 1 .Jan. 2010 to 31. Dec. 2014) of medical records of chemical injury patients who visited our emergency department were reviewed retrospectively. By applying exclusion criteria, 446 patients of 460 patients were selected. RESULTS: Dichloromethane, Toluene, Trichloroethylene, and Xylene were always included within Top 5 of Cweq. Six cases of chemical incidents were reported and in 3 of 6 cases involving Hydrogen fluoride were included during the study period. Male gender and twenties were the most prevalent group. Injury evoking chemicals were Hydrogen fluoride, unknown, complex chemicals (over 2 substances) in sequence. The most frequent site of wounds and injuries was the respiratory tract. Gas among status, intoxication among diagnosis, and discharge among disposition was most numerous in each group. CONCLUSION: There have been no uniform clinical protocols for chemical wounds and injuries due to various kinds of chemicophysical properties and ignorance of antidotes. Therefore conduct of a multicenter cohort study and experiments for ruling out chemicals according to chemicophysical priority as well as development of antidotes and clinical protocols for chemical injury patients is needed.

Acute health effects of accidental chlorine gas exposure.

OBJECTIVES: This study was conducted to report the course of an accidental release of chlorine gas that occurred in a factory in Gumi-si, South Korea, on March 5, 2013. We describe the analysis results of 2 patients hospitalized because of chlorine-induced acute health problems, as well as the clinical features of 209 non-hospitalized patients. METHODS: We analyzed the medical records of the 2 hospitalized patients admitted to the hospital, as well as the medical records and self-report questionnaires of 209 non-hospitalized patients completed during outpatient treatment. RESULTS: Immediately after the exposure, the 2 hospitalized patients developed acute asthma-like symptoms such as cough and dyspnea, and showed restrictive and combined pattern ventilatory defects on the pulmonary function test. The case 1 showed asthma-like symptoms over six months and diurnal variability in peak expiratory flow rate was 56.7%. In case 2, his FEV1 after treatment (93%) increased by 25% compared to initial FEV1 (68%). Both cases were diagnosed as chlorine-induced reactive airways dysfunction syndrome (RADS) on the basis of these clinical features. The most frequent chief complaints of the 209 non-hospitalized patients were headache (22.7%), followed by eye irritation (18.2%), nausea (11.2%), and sore throat (10.8%), with asymptomatic patients accounting for 36.5%. The multiple-response analysis of individual symptom revealed headache (42.4%) to be the most frequent symptom, followed by eye irritation (30.5%), sore throat (30.0%), cough (29.6%), nausea (27.6%), and dizziness (27.3%). CONCLUSIONS: The 2 patients hospitalized after exposure to chlorine gas at the leakage site showed a clinical course corresponding to RADS. All of the 209 non-hospitalized patients only complained of symptoms of the upper airways and mucous membrane irritation.

Acute health effects of accidental chlorine gas exposure

OBJECTIVES: This study was conducted to report the course of an accidental release of chlorine gas that occurred in a factory in Gumi-si, South Korea, on March 5, 2013. We describe the analysis results of 2 patients hospitalized because of chlorine-induced acute health problems, as well as the clinical features of 209 non-hospitalized patients. METHODS: We analyzed the medical records of the 2 hospitalized patients admitted to the hospital, as well as the medical records and self-report questionnaires of 209 non-hospitalized patients completed during outpatient treatment. RESULTS: Immediately after the exposure, the 2 hospitalized patients developed acute asthma-like symptoms such as cough and dyspnea, and showed restrictive and combined pattern ventilatory defects on the pulmonary function test. The case 1 showed asthma-like symptoms over six months and diurnal variability in peak expiratory flow rate was 56.7%. In case 2, his FEV1 after treatment (93%) increased by 25% compared to initial FEV1 (68%). Both cases were diagnosed as chlorine-induced reactive airways dysfunction syndrome (RADS) on the basis of these clinical features. The most frequent chief complaints of the 209 non-hospitalized patients were headache (22.7%), followed by eye irritation (18.2%), nausea (11.2%), and sore throat (10.8%), with asymptomatic patients accounting for 36.5%. The multiple-response analysis of individual symptom revealed headache (42.4%) to be the most frequent symptom, followed by eye irritation (30.5%), sore throat (30.0%), cough (29.6%), nausea (27.6%), and dizziness (27.3%). CONCLUSIONS: The 2 patients hospitalized after exposure to chlorine gas at the leakage site showed a clinical course corresponding to RADS. All of the 209 non-hospitalized patients only complained of symptoms of the upper airways and mucous membrane irritation.