Surveillance of acute nonfatal occupational inhalation injuries treated in US hospital emergency departments, 2014-2017.

BACKGROUND: Acute nonfatal occupational inhalation injuries are caused by exposures to airborne toxicants and contaminants in the workplace. A 1990s study found that US emergency department (ED)-based inhalation injury rates were higher than those seen in the United Kingdom and Canada. This study examines 4 years of hospital ED data to estimate current rates of occupational inhalation injuries. METHODS: Data from the National Electronic Injury Surveillance System Occupational Supplement were used to identify nonfatal occupational inhalation injuries treated in US hospital EDs from 2014 to 2017. A workplace inhalation injury was defined as any worker treated in an ED as a result of inhaling a harmful substance at work. RESULTS: From 2014 to 2017, there were an estimated 2.2 occupational inhalation injuries per 10,000 full-time equivalents (FTE) (95% confidence interval [CI]: 1.6-2.8) treated in EDs, a rate nearly four times that found in Bureau of Labor Statistics data. Although men incurred 60% (95% CI: 56%-64%) of the injuries, the overall injury rates for men and women were similar at 2.3 (95% CI: 1.7-2.9) and 2.1 (95% CI: 1.4-2.7) per 10,000 FTE, respectively. By age group, workers less than 25 years of age were at greater risk of injury at 4.1 injuries per 10,000 FTE (95% CI: 2.8-5.3). CONCLUSIONS: These results illustrate the burden of nonfatal occupational inhalation injuries, providing an understanding of how injuries are distributed based on demographics. While inhalation injury rates have declined over the last two decades, additional research is needed to determine whether interventions have reduced risk, or if the availability of alternate sources of medical treatment is a factor.

Medical claims paid by workers' compensation insurance among US Medicare beneficiaries, 1999-2016.

BACKGROUND: Workers' compensation claims among Medicare beneficiaries have not been described previously. To examine the healthcare burden of work-related injury and illness among Medicare beneficiaries, we assessed the characteristics, healthcare utilization, and financial costs among Medicare beneficiaries with claims for which workers' compensation was the primary payer. METHODS: We extracted final action fee-for-service Medicare claims from 1999 to 2016 where workers' compensation had primary responsibility for claim payment and beneficiary, claim type, diagnoses, and cost information from these claims. RESULTS: During 1999-2016, workers' compensation was the primary payer for 2,010,200 claims among 330,491 Medicare beneficiaries, and 58.7% of these beneficiaries had more than one claim. Carrier claims submitted by noninstitutional providers constituted the majority (94.5%) of claims. Diagnosis codes indicated 19.4% of claims were related to diseases of the musculoskeletal system and connective tissue and 12.9% were related to disease of the circulatory system. Workers' compensation insurance paid $880.4 million for these claims while Medicare paid $269.7 million and beneficiaries paid $37.4 million. CONCLUSIONS: Workers' compensation paid 74% of the total amount to providers for these work-related medical claims among Medicare beneficiaries. Claim diagnoses were similar to those of all workers' compensation claims in the United States. Describing these work-related claims helps identify the healthcare burden due to occupational injury and illness among Medicare beneficiaries resulting from employment and identifies a need for more comprehensive collection and surveillance of work-related medical claims.

Surveillance for Silicosis Deaths Among Persons Aged 15-44 Years - United States, 1999-2015.

Silicosis is usually a disease of long latency affecting mostly older workers; therefore, silicosis deaths in young adults (aged 15-44 years) suggests acute or accelerated disease.* To understand the circumstances surrounding silicosis deaths among young persons, CDC analyzed the underlying and contributing causes† of death using multiple cause-of-death data (1999-2015) and industry and occupation information abstracted from death certificates (1999-2013). During 1999-2015, among 55 pneumoconiosis deaths of young adults with International Classification of Diseases, Tenth Revision (ICD-10) code J62 (pneumoconiosis due to dust containing silica),§ 38 (69%) had code J62.8 (pneumoconiosis due to other dust containing silica), and 17 (31%) had code J62.0 (pneumoconiosis due to talc dust) listed on their death certificate. Decedents whose cause of death code was J62.8 most frequently worked in the manufacturing and construction industries and production occupations where silica exposure is known to occur. Among the 17 decedents who had death certificates listing code J62.0 as cause of death, 13 had certificates with an underlying or a contributing cause of death code listed that indicated multiple drug use or drug overdose. In addition, 13 of the 17 death certificates listing code J62.0 as cause of death had information on decedent's industry and occupation; among the 13 decedents, none worked in talc exposure-associated jobs, suggesting that their talc exposure was nonoccupational. Examining detailed information on causes of death (including external causes) and industry and occupation of decedents is essential for identifying silicosis deaths associated with occupational exposures and reducing misclassification of silicosis mortality.

Introduction to the Summary of Notifiable Noninfectious Conditions and Disease Outbreaks - United States.

With this 2016 Summary of Notifiable Noninfectious Conditions and Disease Outbreaks - United States, CDC is publishing official statistics for the occurrence of nationally notifiable noninfectious conditions and disease outbreaks for the second time in the same volume of MMWR as the annual Summary of Notifiable Infectious Diseases and Conditions (1). As was the case for the 2015 Summary of Notifiable Noninfectious Conditions and Disease Outbreaks (2), this joint publication is the result of a request by the Council of State and Territorial Epidemiologists (CSTE) to provide readers with information on all nationally notifiable conditions and disease outbreaks in a single publication.

Surveillance for Silicosis - Michigan and New Jersey, 2003-2011.

CDC's National Institute for Occupational Safety and Health (NIOSH), state health departments, and other state entities maintain a state-based surveillance program of confirmed silicosis cases. Data on confirmed cases are collected and compiled by state entities and submitted to CDC. This report summarizes information for cases of silicosis that were reported to CDC for 2003-2011 by Michigan and New Jersey, the only states that continue to provide data voluntarily to NIOSH. The data for this report were final as of January 8, 2015. Data are presented in tabular form on the number and distribution of cases of silicosis by year (Table 1), duration of employment in occupations with potential exposure to dust containing respirable crystalline silica (Table 2), industry (Table 3), and occupation (Table 4). The number of cases by year is presented graphically (Figure). This report is a part of the Summary of Notifiable Noninfectious Conditions and Disease Outbreaks - United States, which encompasses various surveillance years but is being published in 2016 (1). The Summary of Notifiable Noninfectious Conditions and Disease Outbreaks appears in the same volume of MMWR as the annual Summary of Notifiable Infectious Diseases (2).

Notes from the Field: Update: Silicosis Mortality - United States, 1999-2013.

Silicosis is a potentially fatal but preventable occupational lung disease caused by inhaling respirable crystalline silica (silica). Chronic silicosis, the most common form, occurs after exposure to relatively low silica concentrations for >10 years. Accelerated silicosis occurs after 5-10 years of exposure to higher silica levels, and acute silicosis can occur after only weeks or months of exposure to extremely high silica concentrations. New national mortality data for silicosis have become available since a previous report on silicosis surveillance was published earlier this year. CDC reviewed multiple cause-of-death mortality files from the National Center for Health Statistics to analyze deaths from silicosis (International Classification of Diseases, 10th Revision diagnosis code J62: a pneumoconiosis due to dust containing silica) reported during 1999-2013. Each record lists one underlying cause of death (the disease or injury that initiated the chain of events that led directly and inevitably to death), and up to 20 contributing causes of death (other significant conditions contributing to death but not resulting in underlying cause). Available death certificates from 35 states were reviewed for the period 2004-2006 to identify occupations associated with silicosis among decedents aged 15-44 years. Results indicate that despite substantial progress in eliminating silicosis, silicosis deaths continue to occur. Of particular concern are silicosis deaths in young adults (aged 15-44 years). These young deaths likely reflect higher exposures than those causing chronic silicosis mortality in older persons, some of sufficient magnitude to cause severe disease and death after relatively short periods of exposure. A total of 12 such deaths occurred during 2011-2013, with nine that had silicosis listed as the underlying cause of death.

Is childhood asthma associated with educational level and longest-held occupation?

Children with asthma can experience chronic morbidity that may interfere with education and career progression. The authors investigated retrospectively whether a history of childhood asthma is associated with educational level and longest-held occupation, by gender. Cross-sectional analysis included a nationally representative sample of 10,452 adults aged ≥20 years who participated in the US National Health and Nutrition Examination Survey (2001-2004). Logistic regression was used to assess associations between a childhood-asthma history and educational level, employment, and longest-held occupation. An estimated 6.9% of men and 5.8% of women had a childhood-asthma history. Persons with a childhood-asthma history tended to have a higher educational level than those with no asthma history. Among those who ever worked, and after adjustment for age and race/ethnicity, men with a childhood-asthma history were more likely to work in health-diagnosing occupations, other professional occupations, and as cooks; women with a childhood-asthma history were more likely to work in management-related, entertainment-related, and health service occupations. Compared with those with no asthma history, persons with a childhood-asthma history tended to achieve a higher educational level and, if they worked, were more likely to work in particular occupations.

The Diesel Exhaust in Miners Study: V. Evaluation of the Exposure Assessment Methods.

Exposure to respirable elemental carbon (REC), a component of diesel exhaust (DE), was assessed for an epidemiologic study investigating the association between DE and mortality, particularly from lung cancer, among miners at eight mining facilities from the date of dieselization (1947-1967) through 1997. To provide insight into the quality of the estimates for use in the epidemiologic analyses, several approaches were taken to evaluate the exposure assessment process and the quality of the estimates. An analysis of variance was conducted to evaluate the variability of 1998-2001 REC measurements within and between exposure groups of underground jobs. Estimates for the surface exposure groups were evaluated to determine if the arithmetic means (AMs) of the REC measurements increased with increased proximity to, or use of, diesel-powered equipment, which was the basis on which the surface groups were formed. Estimates of carbon monoxide (CO) (another component of DE) air concentrations in 1976-1977, derived from models developed to predict estimated historical exposures, were compared to 1976-1977 CO measurement data that had not been used in the model development. Alternative sets of estimates were developed to investigate the robustness of various model assumptions. These estimates were based on prediction models using: (i) REC medians rather AMs, (ii) a different CO:REC proportionality than a 1:1 relation, and (iii) 5-year averages of historical CO measurements rather than modeled historical CO measurements and DE-related determinants. The analysis of variance found that in three of the facilities, most of the between-group variability in the underground measurements was explained by the use of job titles. There was relatively little between-group variability in the other facilities. The estimated REC AMs for the surface exposure groups rose overall from 1 to 5 µg m(-3) as proximity to, and use of, diesel equipment increased. The alternative estimates overall were highly correlated (∼0.9) with the primary set of estimates. The median of the relative differences between the 1976-1977 CO measurement means and the 1976-1977 estimates for six facilities was 29%. Comparison of estimated CO air concentrations from the facility-specific prediction models with historical CO measurement data found an overall agreement similar to that observed in other epidemiologic studies. Other evaluations of components of the exposure assessment process found moderate to excellent agreement. Thus, the overall evidence suggests that the estimates were likely accurate representations of historical personal exposure levels to DE and are useful for epidemiologic analyses.

The diesel exhaust in miners study: I. Overview of the exposure assessment process.

This report provides an overview of the exposure assessment process for an epidemiologic study that investigated mortality, with a special focus on lung cancer, associated with diesel exhaust (DE) exposure among miners. Details of several components are provided in four other reports. A major challenge for this study was the development of quantitative estimates of historical exposures to DE. There is no single standard method for assessing the totality of DE, so respirable elemental carbon (REC), a component of DE, was selected as the primary surrogate in this study. Air monitoring surveys at seven of the eight study mining facilities were conducted between 1998 and 2001 and provided reference personal REC exposure levels and measurements for other agents and DE components in the mining environment. (The eighth facility had closed permanently prior to the surveys.) Exposure estimates were developed for mining facility/department/job/year combinations. A hierarchical grouping strategy was developed for assigning exposure levels to underground jobs [based on job titles, on the amount of time spent in various areas of the underground mine, and on similar carbon monoxide (CO, another DE component) concentrations] and to surface jobs (based on the use of, or proximity to, diesel-powered equipment). Time trends in air concentrations for underground jobs were estimated from mining facility-specific prediction models using diesel equipment horsepower, total air flow rates exhausted from the underground mines, and, because there were no historical REC measurements, historical measurements of CO. Exposures to potentially confounding agents, i.e. respirable dust, silica, radon, asbestos, and non-diesel sources of polycyclic aromatic hydrocarbons, also were assessed. Accuracy and reliability of the estimated REC exposures levels were evaluated by comparison with several smaller datasets and by development of alternative time trend models. During 1998-2001, the average measured REC exposure level by facility ranged from 40 to 384 µg m⁻³ for the underground workers and from 2 to 6 µg m⁻³ for the surface workers. For one prevalent underground job, 'miner operator', the maximum annual REC exposure estimate by facility ranged up to 685% greater than the corresponding 1998-2001 value. A comparison of the historical CO estimates from the time trend models with 1976-1977 CO measurements not used in the modeling found an overall median relative difference of 29%. Other comparisons showed similar levels of agreement. The assessment process indicated large differences in REC exposure levels over time and across the underground operations. Method evaluations indicated that the final estimates were consistent with those from alternative time trend models and demonstrated moderate to high agreement with external data.

Cleaning Products and Work-Related Asthma, 10 Year Update.

OBJECTIVE: To describe the frequency of work-related asthma (WRA) and characteristics of individuals with exposure to cleaning products 1998 to 2012, compared with 1993 to 1997. METHODS: Cases of WRA from products used for cleaning or disinfecting surfaces were identified from California, Massachusetts, Michigan (1998 to 2012), New Jersey (1998 to 2011), and New York (2009 to 2012). RESULTS: There were 1199 (12.4%) cleaning product cases among all 9667 WRA cases; 77.8% women, 62.1% white non-Hispanic, and average age of 43 years. The highest percentages worked in healthcare (41.1%), and were building cleaners (20.3%), or registered nurses (14.1%). CONCLUSIONS: The percentage of WRA cases from exposure to cleaning products from 1998 to 2012 was unchanged from 1993 to 1997 indicating that continued and additional prevention efforts are needed to reduce unnecessary use, identify safer products, and implement safer work processes.

Medicare Claims Paid by the Federal Black Lung Benefits Program: US Medicare Beneficiaries, 1999 to 2016.

OBJECTIVE: To establish the burden of totally disabling respiratory impairment among coal miners, we identified the healthcare utilization and cost for Medicare claims where the Federal Black Lung Program (FBLP) was the primary payer. METHODS: We extracted FBLP claims from 1999 to 2016 institutional Medicare data along with beneficiary, comorbidity, and claim cost information. Healthcare utilization was evaluated and compared to the 2016 Medicare population. RESULTS: The FBLP was the primary payer on 75,690 claims from 19,700 beneficiaries and paid an increasing percentage of the total paid to providers annually. Claims decreased from 1999 to 2016 but cost per claim increased. Beneficiaries were hospitalized and visited the ER for respiratory and cardiovascular conditions. CONCLUSIONS: Medicare beneficiaries with FBLP primary payer claims have higher healthcare utilization and comorbidities compared with Medicare enrollees, indicative of increased financial and healthcare burden.

Farm work-related asthma among US primary farm operators.

The objective of this study was to estimate the prevalence of current asthma and the proportion of current asthma that is related to work on the farm among primary farm operators. The 2011 Farm and Ranch Safety Survey data were used to produce estimates and prevalence odds ratios. An estimated 5.1% of farm operators had asthma. Of these, 15.4% had farm work-related asthma. Among operators with farm work-related asthma, 54.8% (95% confidence interval [CI]: 41.8%-68.2%) had an asthma attack in the prior 12 months and 33.3% (95% CI: 21.2%-45.4%) had an asthma attack that occurred while doing farm work. Of those who had an asthma attack that occurred while doing farm work, 65.0% associated their asthma attack with plant/tree materials. This study provides updated information on asthma and the proportion of current asthma that is related to work on the farm and identifies certain groups of farm operators that might benefit from workplace asthma prevention intervention.

Cis-4-[(18)F]fluoro-L-proline PET imaging of pulmonary fibrosis in a rabbit model.

UNLABELLED: A fluorinated analog of proline amino acid, cis-4-[(18)F]fluoro-L-proline (FP), was tested for potential use in PET for detection and evaluation of pulmonary response to respirable crystalline silica. The purpose of the study was to determine whether PET imaging with FP is sensitive for detection of pulmonary fibrosis. METHODS: Experimental silicosis was produced in rabbits by airway instillation of 300 mg respirable silica in 0.9% sterile saline; control rabbits received only saline. After 1, 2, 4, or 5 mo, animals were injected with 37 MBq (1 mCi) FP, and imaged in sets of 2 to 3 in a PET scanner using a dynamic scanning protocol over a 3-h period. Each imaging set contained at least 1 control rabbit. FP uptake in each lung was scored from 0 to 5 (PET score) by consensus of 3 readers blinded to animals' exposure status. Animals were humanely killed 2 d after the last imaging, and tissue sections from each lung lobe were graded from 0 to 5 by histopathology examination (histopathology score) for severity and distribution of fibrosis. RESULTS: Silicotic animals had significantly higher (P < 0.05) PET scores at each time point than did control animals. Repeated-measures ANOVA showed significant differences in PET scores between silicotic and control animals for the total lung field, but there were no statistically significant time trends for either group. Presence of fibrosis (i.e., histopathology score > 1) showed a significant association with elevated PET score (i.e., PET score > 1) using Fisher's exact test (P < 0.05). PET scores also showed excellent predictive ability, as all animals (18/18) with fibrosis also had elevated PET scores, and 95% (18/19) of animals with PET scores > 1 showed evidence of fibrosis. Localization of activity to specific lung areas was less exact, perhaps due in part to the small animal size for the resolution of the clinical PET imager used. PET scores were elevated (>1) for 67% (10/15) of silicotic right lungs and 75% (12/16) of silicotic left lungs; fibrosis scores > 1 were measured in 91% (10/11) of right lungs with PET scores > 1, and in 92% (12/13) of such left lungs. CONCLUSION: The FP tracer provided sensitive and specific identification of silicotic animals in early stages of the disease. This suggests that FP PET imaging has the potential sensitivity to detect active fibrosis in silicosis and other lung diseases. Additional studies are needed to determine the specificity of the FP tracer for fibrosis versus inflammatory processes.

Respirator use among U.S. farm operators: evidence from the 2006 Farm and Ranch Safety Survey.

The objective of this study was to estimate the national prevalence of respirator use among primary farm operators in the United States. The authors analyzed the 2006 Farm and Ranch Safety Survey data collected for 12,278 actively farming primary farm operators. Weighted prevalence and adjusted prevalence ratios (PRs) of respirator use were calculated by farm operator characteristics, farm characteristics, and selected exposures/hazards. Of the estimated 2.1 million farm operators, 37.2% used a respirator on their farm. Respirator use prevalence was significantly higher among operators aged 16-34 years than those aged ≥65 years (46.9% vs. 30.0%; PR = 1.6); male than female operators (39.0% vs. 24.4%; PR = 1.6); operators managing crop farms than operators managing livestock farms (40.9% vs. 33.7%; PR = 1.2); and operators managing farms with value of sales ≥$100,000 than operators managing farms with value of sales ≤$9999 (57.4% vs. 31.4%; PR = 1.8). Of the operators who used a respirator, 69.9% used while working in a dusty environment, 22.6% used while applying/handling pesticides, and 30.4% used while doing other farm-related activities. These results show that an estimated one third of operators used respirators in 2006, and respirator use is most frequent among operators working in a dusty environment. Additional research identifying specific exposures for which respirators or dust masks are used, barriers to respirator or dust mask use, motivators for wearing respirators, and opportunities to increase the use of respiratory protection among farm operators, particularly on smaller farms, is needed.

The Diesel Exhaust in Miners study: a cohort mortality study with emphasis on lung cancer.

BACKGROUND: Current information points to an association between diesel exhaust exposure and lung cancer and other mortality outcomes, but uncertainties remain. METHODS: We undertook a cohort mortality study of 12 315 workers exposed to diesel exhaust at eight US non-metal mining facilities. Historical measurements and surrogate exposure data, along with study industrial hygiene measurements, were used to derive retrospective quantitative estimates of respirable elemental carbon (REC) exposure for each worker. Standardized mortality ratios and internally adjusted Cox proportional hazard models were used to evaluate REC exposure-associated risk. Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death. RESULTS: Standardized mortality ratios for lung cancer (1.26, 95% confidence interval [CI] = 1.09 to 1.44), esophageal cancer (1.83, 95% CI = 1.16 to 2.75), and pneumoconiosis (12.20, 95% CI = 6.82 to 20.12) were elevated in the complete cohort compared with state-based mortality rates, but all-cause, bladder cancer, heart disease, and chronic obstructive pulmonary disease mortality were not. Differences in risk by worker location (ever-underground vs surface only) initially obscured a positive diesel exhaust exposure-response relationship with lung cancer in the complete cohort, although it became apparent after adjustment for worker location. The hazard ratios (HRs) for lung cancer mortality increased with increasing 15-year lagged cumulative REC exposure for ever-underground workers with 5 or more years of tenure to a maximum in the 640 to less than 1280 µg/m(3)-y category compared with the reference category (0 to <20 µg/m(3)-y; 30 deaths compared with eight deaths of the total of 93; HR = 5.01, 95% CI = 1.97 to 12.76) but declined at higher exposures. Average REC intensity hazard ratios rose to a plateau around 32 µg/m(3). Elevated hazard ratios and evidence of exposure-response were also seen for surface workers. The association between diesel exhaust exposure and lung cancer risk remained after inclusion of other work-related potentially confounding exposures in the models and were robust to alternative approaches to exposure derivation. CONCLUSIONS: The study findings provide further evidence that exposure to diesel exhaust increases risk of mortality from lung cancer and have important public health implications.

The Diesel Exhaust in Miners study: a nested case-control study of lung cancer and diesel exhaust.

BACKGROUND: Most studies of the association between diesel exhaust exposure and lung cancer suggest a modest, but consistent, increased risk. However, to our knowledge, no study to date has had quantitative data on historical diesel exposure coupled with adequate sample size to evaluate the exposure-response relationship between diesel exhaust and lung cancer. Our purpose was to evaluate the relationship between quantitative estimates of exposure to diesel exhaust and lung cancer mortality after adjustment for smoking and other potential confounders. METHODS: We conducted a nested case-control study in a cohort of 12 315 workers in eight non-metal mining facilities, which included 198 lung cancer deaths and 562 incidence density-sampled control subjects. For each case subject, we selected up to four control subjects, individually matched on mining facility, sex, race/ethnicity, and birth year (within 5 years), from all workers who were alive before the day the case subject died. We estimated diesel exhaust exposure, represented by respirable elemental carbon (REC), by job and year, for each subject, based on an extensive retrospective exposure assessment at each mining facility. We conducted both categorical and continuous regression analyses adjusted for cigarette smoking and other potential confounding variables (eg, history of employment in high-risk occupations for lung cancer and a history of respiratory disease) to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death (case subjects)/reference date (control subjects). All statistical tests were two-sided. RESULTS: We observed statistically significant increasing trends in lung cancer risk with increasing cumulative REC and average REC intensity. Cumulative REC, lagged 15 years, yielded a statistically significant positive gradient in lung cancer risk overall (P (trend) = .001); among heavily exposed workers (ie, above the median of the top quartile [REC ≥ 1005 µg/m(3)-y]), risk was approximately three times greater (OR = 3.20, 95% CI = 1.33 to 7.69) than that among workers in the lowest quartile of exposure. Among never smokers, odd ratios were 1.0, 1.47 (95% CI = 0.29 to 7.50), and 7.30 (95% CI = 1.46 to 36.57) for workers with 15-year lagged cumulative REC tertiles of less than 8, 8 to less than 304, and 304 µg/m(3)-y or more, respectively. We also observed an interaction between smoking and 15-year lagged cumulative REC (P (interaction) = .086) such that the effect of each of these exposures was attenuated in the presence of high levels of the other. CONCLUSION: Our findings provide further evidence that diesel exhaust exposure may cause lung cancer in humans and may represent a potential public health burden.

Physician recognition of work-related asthma among US farm operators.

BACKGROUND AND OBJECTIVES: The occupational history of every adult patient with asthma provides information critical to the proper diagnosis and effective prevention of work-related asthma. This study determined the proportion of farm operators that reported an asthma attack while doing farm work that required the use of an inhaler or other medical treatment but who had not been told by a doctor, nurse, or other health professional that their asthma was related to work on the farm. METHODS: Asthma and asthma attack prevalences were estimated using data on a nationally representative sample of 12,278 active farm operators who participated in the 2006 Farm and Ranch Safety Survey. RESULTS: An estimated 4.9% of operators reported current asthma. Of these, an estimated 24.8% had been told that their asthma was related to work on the farm. Of those not so informed, 21.6% reported an asthma attack at work in the 12 months prior to the interview. CONCLUSIONS: A large proportion of farm operators who had not been told that their asthma was related to work on the farm experienced an asthma attack that occurred while doing farm work. These results suggest the need for improving clinicians' occupational health practices and clinician-patient communication.