Methods: Morbidity
Prevalence (Lifetime Asthma, Current Asthma, Asthma Attack, Chronic Obstructive Pulmonary Disease, Cigarette Smoking Status, Any Tobacco Use, Smokeless Tobacco Use, and Dual Tobacco Use)
The estimated annual average prevalence of lifetime asthma, current asthma, asthma attack, chronic obstructive pulmonary disease, cigarette smoking status, any tobacco use, smokeless tobacco use, and dual tobacco use was based on the public-use National Health Interview Survey (NHIS) for adults aged ≥18 years, from the National Center for Health Statistics (NCHS), (http://www.cdc.gov/nchs/nhis.htm).
Lifetime asthma was defined as a "yes" response to the question "Have you ever been told by a doctor or other health professional that you had asthma?" Current asthma was defined as a "yes" response to the questions "Have you ever been told by a doctor or other health professional that you had asthma?"" and "Do you still have asthma?" Asthma attack was defined as a "yes" response to the question "During the past 12 months, have you had an episode of asthma or an asthma attack?"
Chronic obstructive pulmonary disease (COPD) was defined as a "yes" response to one or both of the following questions: "During the past 12 months, have you been told by a doctor or other health professional that you had chronic bronchitis?" or "Have you ever been told by a doctor or other health professional that you had emphysema?"
Cigarette smoking status was classified in three groups: nonsmokers, former smokers, and current smokers. Nonsmokers were defined as those who smoked fewer than 100 cigarettes during their entire life. Former smokers were defined as those who smoked at least 100 cigarettes in their entire life and do not currently smoke. Current smokers were defined as those who smoked at least 100 cigarettes in their entire life and are currently smoking every day or some days.
Smokeless tobacco users were defined as adults who responded "yes" to the questions "Have you ever used chewing tobacco, such as Redman, Levi Garrett, or Beech-Nut even one time?" and "Do you now use chewing tobacco every day/some days/not at all?" Any tobacco users were defined as adults who responded "yes" to the questions "Do you use snuff or chewing tobacco or cigar or cigarettes?" and "Do you now use snuff, chewing tobacco or smoking cigars or smoking cigarettes every day/some days/not at all?" Dual tobacco users were defined as adults who responded "yes" to the questions "Do you currently use cigarettes and smokeless tobacco products?" and "Do you now use cigarettes and smokeless tobacco products every day/some days/not at all?"
Working adults were defined as those who responded "yes" to one of three options about their working status: 1) "working at a job or business," or 2) "with a job or business but not at work," or 3) "working, but not for pay, at a family-owned job or business" and were not retired or laid off during the week before the survey interview. Information on current industry and occupation was collected from all individuals who were employed during the week before the survey interview. The NHIS public-use data files containing 2-digit industry and occupation recodes were used. The NCHS 2-digit industry and occupation recodes were derived from the 4-digit codes based on the NAICS and SOC codes received from the U.S. Census Bureau. Further detailed information on the NCHS industry and occupation coding can be accessed on the NCHS website, ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Datasets/NHIS/2004_2009_IO_note_to_users.pdf. The details of the industry and occupation categories created by NCHS can be accessed on pages 333–336 at ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/Dataset_Documentation/NHIS/2011/samadult_layout.pdf.
Estimated annual average prevalences of lifetime asthma, current asthma, asthma attack, COPD, cigarette smoking status, smokeless tobacco use, any tobacco use, and dual tobacco use by current industry, current occupation and sex were calculated. The NCHS provided a sample weight variable (WTFA_SA) for each survey year to weight the data to be nationally representative. For lifetime asthma, current asthma, asthma attack, COPD, and cigarette smoking status 8 years of data (2004–2011) were used and an average sample weight was applied. For any tobacco use, smokeless tobacco use, and dual tobacco use the 2010 NHIS data was used and the sample weight for that year was applied. Survey respondents with unknown or missing information were excluded from the denominator when calculating prevalences. SAS® software (SAS Institute Inc., Cary, NC) was used to analyze the data and to calculate the estimated frequencies and prevalences with corresponding 95% confidence intervals.
Prevalence (Coal Workers' Pneumoconiosis)
Prevalence of coal workers' pneumoconiosis (CWP) is reported by tenure and time period. The Coal Workers' Health Surveillance Program (CWHSP) defines radiographic evidence of CWP in chest x-rays as the presence of either small opacities with a profusion category greater than or equal to International Labour Office (ILO) category 1/0, large opacities (i.e., larger than one centimeter in diameter), or both. Administrative and regulatory guidelines have varied over the life of the program. The prevalence of CWP is presented by underground coal mining tenure of miners who participated in the surveys. Tenure calculations were based upon the work histories reported by each miner at the time of the examination. For presentations by five-year periods, only the most recent examination in that period was used for miners with more than one radiograph.
Incidence (Occupational Respiratory Illnesses)
Estimated numbers of work-related respiratory illness (with days away from work) and incidence rates of occupational respiratory conditions due to toxic agents were generally abstracted from the Bureau Labor Statistics annual reports of occupational injuries and illnesses.
Association of Occupational and Environmental Clinics Diagnoses and Hazards
The frequency distributions of work-related respiratory conditions diagnosed in the Association of Occupational and Environmental Clinics (AOEC) and the respiratory hazards associated with these respiratory diagnoses were tabulated from summary reports prepared by AOEC. For hazards other than asbestos, only the top two are listed and the number in parentheses represents the number of diagnoses associated with that reported hazard. The list of the most frequently associated respiratory hazards (excluding asbestos) is a partial listing of all occupational hazards associated with the work-related respiratory conditions. All remaining occupational hazards are aggregated in an "All other" category.
Discharges from Short-Stay Non-federal Hospitals (Asbestosis, Coal Workers' Pneumoconiosis, Silicosis)
Estimated numbers of discharges from short-stay non-federal hospitals were tabulated from the National Hospital Discharge Survey (NHDS) data files provided by the National Center for Health Statistics. Estimated numbers were based on any mention of asbestosis, coal workers' pneumoconiosis, or silicosis from among the seven diagnosis codes provided in the data files for discharged patients who were of age 15 years and older.