Work-Related Lung Disease (WoRLD) Surveillance System

MORTALITY

Number of Deaths
In this report, the number of deaths for each occupational respiratory condition is the number of decedents for which the condition was coded as a cause of death on the entity axis in the National Center for Health Statistics (NCHS) multiple cause-of-death data files.  [Note: In prior editions of the Work-Related Lung Disease Surveillance (WoRLD) Report, the numbers of deaths were generally based on the numbers of decedents for which each condition was coded as a cause of death on the record axis. Changing to the entity axis multiple cause-of-death permits more complete ascertainment of the diseases of interest.]  See Detail Record Layout at http://www.cdc.gov/nchs/about/major/dvs/mcd/1998mcd.htm for a discussion of the appropriate uses, advantages, and disadvantages of the multiple cause-of-death code fields (entity axis and record axis).

In this report, percentages of deaths for the pneumoconioses, malignant mesothelioma, and hypersensitivity pneumonitis that NCHS coded as the underlying cause of death are listed by year.  Since 1999, deaths with underlying cause-of-death International Classification of Diseases (ICD)-10 code J65 (pneumoconiosis associated with tuberculosis) are included in the underlying cause-of-death tabulations when each specified type of pneumoconiosis is coded as a cause of death on the entity axis.  Similarly, deaths with underlying cause-of-death code J92.0 (pleural plaque with presence of asbestos) are included in asbestosis underlying cause-of-death tabulations.

The sum of individual pneumoconiosis (i.e., asbestosis, coal workers’ pneumoconiosis, silicosis, byssinosis, and unspecified/other pneumoconiosis) death totals may be greater than the total number of deaths for all pneumoconioses because some decedents have more than one type of pneumoconiosis listed on their death certificates.  The sum of individual malignant mesothelioma (i.e., pleura, peritoneum, other sites, and unspecified) death totals may be greater than the total number of deaths for all sites because some decedents have more than one type of malignant mesothelioma listed on their death certificates.  To avoid inadvertent disclosure of confidential data, county-level statistics in this report were computed for time periods that overlap with similar statistics published in the WoRLD Report 2002 by at least 5 years (e.g., 1985–1999 and 1995–2004), and omit data from counties having less than four deaths with the condition of interest.  Reported deaths are restricted to U.S. residents, 15 years or older, based on state of residence at death. Race is classified as white, black, and all others.  Industry and occupation classifications are described later in this appendix.

Crude Death Rates
To compute annual cause-specific crude death rates, the total number of decedents, 15 years and older, with a specified condition coded as a cause of death on the entity axis of the NCHS data files in a given year was divided by the population, 15 years and older, of the same geopolitical unit in the same year. Race- and sex-specific rates were computed from the appropriate subsets of the data.  Rates were calculated annually for each specified condition from 1968 through 2004, as well as for selected periods.   Crude death rates for all conditions except malignant mesothelioma, which has only been classified as a separate condition since 1999 (see Appendix C), were computed at the national, state, and county level for the multi-year period 1995–2004.  Malignant mesothelioma rates were computed for 1999–2004 at the national and state level, and for 2000–2004 at the county level.  For each time period, the average annual number of decedents, 15 years and older, with a specified condition was divided by the mid-year population (2002 for malignant mesothelioma; 2000 for all other conditions), 15 years and older, of the same geopolitical unit.

Comparability ratios (http://www.cdc.gov/nchs/datawh/statab/unpubd/comp.htm) were not applied to rates.  No adjustments were made to account for any potential variation in the classification of respiratory diseases and conditions across ICD revisions.

Age-Adjusted Death Rates
Age-adjusted death rates presented in this report were based on deaths with the condition of interest coded as a cause of death on the entity axis of the NCHS data files.  Rates were calculated annually for each specified condition from 1968 through 2004, as well as for selected periods.  For a given year, the age-adjusted rates represent the rates that would have been observed if the age-specific rates for specified age groups had occurred in a population with the same age distribution as that of the standard population.  To conform with current NCHS guidelines, the U.S. Year 2000 Standard Population was used as the standard (all editions prior to the WoRLD Report 2002  used the 1940 standard population). The specific age intervals used were 15–24, 25–34, 35–44, 45–54, 55–64, 65–74, 75–84, and 85 years and older.  Rates for the entire U.S. population and for each sex-race group were age-adjusted separately, using the same standard population.

Age-adjusted rates were computed by the direct method. First, the annual age-specific rates for the population of interest were calculated. The product of the age-specific rates and the number in the comparable age-specific group in the standard population equals the expected number of deaths per million population for each age group. The total expected numbers of deaths were then obtained by summing over all age groups. The total expected number of deaths was divided by the sum of the standard population and the resulting quotient was multiplied by 1,000,000 to produce the age-adjusted rate (per million).

Age-adjusted rates were computed at the national and state level for the multi-year period 1995–2004.  Rates were computed at the county level either for up to three 10-year periods (1975–1984, 1985–1994, and 1995–2004), or for a single 5-year period (2000–2004), depending on whether or not the condition of interest was discretely classified during those time periods (see Appendix C).  For each time period (1975–1984, 1985–1994, 1995–2004, and 2000–2004), age-specific rates first were computed by dividing the average annual number of deaths in each age group by the corresponding age-grouped, mid-year population (1980, 1990, 2000, and 2002, respectively) in the comparable geopolitical unit. Age-adjusted rates then were computed as described above.

Years of Potential Life Lost (YPLL)
YPLL were based on deaths with the condition of interest coded as a cause of death on the entity axis of the NCHS data files.  They were calculated using the method described by the Centers for Disease Control (CDC) (MMWR December 19, 1986/35(2S);1s-11s at http://www.cdc.gov/mmwr/preview/mmwrhtml/00001773.htm).  YPLL were calculated both to age 65 and to life expectancy. YPLL to age 65 may be considered as a loss of years from a traditional working life, while YPLL to life expectancy may be considered as a loss of years from the overall life span.  To compute YPLL to life expectancy, the number of deaths in each race/sex age group (the same age intervals used for computing age-adjusted rates) first was multiplied by the difference between the mid-point of the age group and life expectancy for that race/sex age group.  Life tables published annually by NCHS (http://www.cdc.gov/nchs/products/pubs/pubd/lftbls/life/1966.htm) were used to determine race/sex life-expectancies for white males, white females, black males, black females.  The overall U.S. population life expectancy was used for other male and other female.  To compute YPLL to age 65, the number of deaths in age groups 15–24 through 55–64 was multiplied by the difference between 65 years and the mid-point of each age group (e.g., 65 minus 20 years for the 15–24 age group).  These age-specific YPLLs then were summed over all age groups to obtain total YPLLs (to life expectancy, and to age 65) for each race/sex/year from 1995–2004.
 
State-specific YPLLs (to life expectancy) per death also were calculated for the period 1995–2004. To calculate this index, the total number of all race/sex deaths in each age group was multiplied by the corresponding U.S. population life expectancy, then summed over all age groups to obtain the total YPLL, and then divided by the total number of deaths for each state during this time period.

Rank Order
For each state, a rank order is presented for each of several mortality measures. Depending on the specific mortality measures, a rank order of "1" indicates the greatest number of deaths, highest death rate, or highest YPLL among all states in the U.S.

Most Frequently Recorded Industries/Occupations
In this report, the ten most frequently recorded Bureau of Census (BoC) industries and occupations with at least two decedents are listed for specified causes of death (from selected states and years in Appendix E). Where more than one industry/occupation was tied for tenth place, all those that were tied are listed.

Proportionate Mortality Ratio (PMR)
The data used for PMR analyses are a subset of the NCHS multiple cause-of-death files for which usual industry and occupation codes were available and met quality criteria set by NCHS (see Appendix E for a list of states and years for which data qualified).

The PMR is defined as the observed number of deaths with the condition of interest coded as a cause of death on the entity axis of the NCHS data files in a specified industry/occupation (from selected states and years in Appendix E), divided by the expected number of deaths with that condition. The expected number of deaths is the total number of deaths in the BoC industry or occupation of interest multiplied by a proportion defined as the number of cause-specific deaths for the condition of interest in all industries/occupations, divided by the total number of deaths in all industries/occupations; this includes deaths in retired, non-paid, homemaker, and unreported industries/occupations.  The PMRs in this report, and those published in the WoRLD Report 2002, were internally adjusted by five-year age groups (i.e., 15–19, 20–24, . . . 110–114, and 115 years and over), sex, and race (i.e., white, black, and all other).  Confidence intervals were calculated assuming Poisson distribution of the data.

A PMR greater than 1.0 indicates that there were more deaths associated with the condition in a specified occupation or industry than expected. This report includes only those industries/occupations with five or more decedents with the condition of interest and a lower 95% confidence limit exceeding 1.0 (in some instances the lower 95% confidence limit may equal 1.0 due to rounding).

MORBIDITY

Prevalence (Asthma, Chronic Obstructive Pulmonary Disease, and Smoking)
The estimated prevalence of asthma, chronic obstructive pulmonary disease (COPD), and cigarette smoking was based on the 1997–2004 National Health Interview Survey (NHIS) data (http://www.cdc.gov/nchs/products/elec_prods/subject/nhis.htm). Presence of 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?”  In this report we also included the prevalence for current asthma which 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?” COPD was defined as a “yes” response to either of the following questions: (1) “During the past 12 months, have you been told by a doctor or other health professional that you had chronic bronchitis?” or (2) “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 less 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.

Data on current industry and occupation were collected from all individuals who were employed during the week before the interview took place and were coded on the basis of the revised 1987 Standard Industrial (SIC) and Occupational Classification (SOC), respectively. Due to confidentiality reasons, the industry and occupation codes were regrouped into 2-digit codes for the public use data files. These recodes were based on industry and occupation groups and subgroups consistent with the existing SIC and SOC structures. These coding categories are provided in the NHIS sample adult file section and can be accessed on the website at http://www.cdc.gov/nchs/about/major/nhis/quest_data_related_1997_forward.htm.

Estimated prevalence rates of asthma, COPD and smoking status by gender, current industry and occupation were calculated using sample weights and adjustment for non-responses. For asthma and COPD cases, prevalences were also calculated by their smoking status. Cases with unknown or missing information were excluded from the denominator when calculating a weighted estimate for the prevalence of asthma.  SAS 9.1 software (SAS Institute Inc., Cary, NC) was used to analyze data and to calculate the estimated frequencies, variances, 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’ X-ray Surveillance Program (CWXSP) 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 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 reported by five-year periods, beginning in 1970, with the miners stratified by their underground coal mining tenure at the time of the examination. Tenure calculations were based upon the work histories reported by each miner at the time of the examination. For miners with more than one radiograph during a five-year period, only the most recent examination in that period was used.

Incidence Rates (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 BLS annual reports of occupational injuries and illnesses. 

Association of Occupational and Environmental Clinics (AOEC) Diagnoses and Hazards
In this report, the frequency distributions of work-related respiratory conditions diagnosed in AOEC clinics and the respiratory hazards associated with these respiratory diagnoses were tabulated from three summary reports prepared by AOEC for 1994–1996, 1997–2000, and 2001–2004. 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 NCHS. Estimated numbers were based on any mention of asbestosis, CWP, or silicosis from among the seven diagnosis codes provided in the data files for discharged patients age 15 years and older.

Work-Related Asthma (WRA): Surveillance Case Classification
In this report, Sentinel Event Notification System for Occupational Risks (SENSOR) WRA data is grouped based on case classification criteria into work-aggravated asthma (WAA) and new-onset asthma (NOA).  NOA is further classified as either reactive airways dysfunction syndrome (RADS) or occupational asthma and its sub-classifications (see Appendix G: Decision Logic for Work-Related Asthma). In some instances WRA cases may meet the requirements of the surveillance case definition for a confirmed case without sufficient information for classification.  These cases are noted as “unclassified.”

Work-Related Asthma (WRA): Reported Putative Exposures
In this report, putative agents associated with cases of WRA were grouped using established AOEC categories and sub-categories¹ or combined individual exposure codes (e.g., AOEC code 320.01 and 320.33 were combined into a single Indoor Air Pollutants category).  These categories contain agents of similar use or chemical nature.  A single case of WRA may be associated with up to three putative agents and as a result may be counted in more than one category.  The designation of agents as occupational asthmagens on the AOEC exposure code list is made according to a protocol (see Revised Protocol: Criteria for Designating Substances as Occupational Asthmagens on the AOEC List of Exposure Codes at http://www.aoec.org/content/Asthmagen_Protocol_4-9-05_revision.pdf).

EXPOSURE

Occupational Exposure Limits
Permissible Exposure Limits. The Occupational Safety and Health Administration (OSHA) and the Mine Safety and Health Administration (MSHA) each enforce regulations that establish the legal limits of workplace exposures to pneumoconiotic agents. These legal limits are described in this report as permissible exposure limits (PELs), although the regulations sometimes use the term “standard” or “exposure limit.”

Although OSHA has PELs for the maritime industry [29 CFR 1915], very few samples have been collected and are not reported here.

The OSHA PELs for several pneumoconiotic agents were changed on March 1, 1989, but a legal challenge to the modified OSHA PELs was upheld, and the modified OSHA PELs reverted to the previous OSHA PELs on March 23, 1993. Therefore, data for respirable quartz, selected pneumoconiotic agents, and all pneumoconiotic agents are reported for the three time periods: 1979–1988, 1989–1992, and 1993–2003. Some pneumoconiotic agents had a substance-specific OSHA PEL only from March 1, 1989 to March 22, 1993, including: aluminum as welding fumes, respirable dust of natural graphite, mica containing less than 1% crystalline silica, tin oxide, inorganic compounds of tin oxide, fused respirable silica dust, fibrous talc not containing tremolite, talc not containing asbestos, insoluble tungsten and compounds, and welding fumes (total particulate).

The MSHA metal/nonmetal mining PELs for pneumoconiotic agents were adopted from the 1973 edition of the American Conference of Governmental Industrial Hygienists (ACGIH®) publication entitled TLV®s Threshold Limit Values for Chemical Substances in Workroom Air Adopted by ACGIH for 1973.  MSHA has not adopted PELs for the following pneumoconiotic agents: tin oxide dust/fume, inorganic dusts of tin, insoluble tungsten dusts/fumes, and welding fumes (total particulate). In this report, a MSHA PEL of 10 milligrams per cubic meter (mg/m3) is used for welding fumes (total particulate) through 1993, but since then it has been MSHA policy not to collect samples for welding fumes.

OSHA and MSHA do not have PELs specific for crystalline silica. The PELs apply to respirable dust containing crystalline silica, and the allowable exposure to respirable dust is reduced as the crystalline silica content increases. The formulas for allowable exposure vary with the agency and the industry. In metal/nonmetal mining, the MSHA PEL is the same as the OSHA PEL for respirable dust containing at least 1% quartz:
 

However, OSHA adopted a PEL of 0.1 mg/m3 for quartz that was enforced from March 1, 1989 through March 22, 1993.

Since December 1972, the MSHA PEL for respirable coal mine dust has been 2 mg/m3 MRE² unless the quartz content of the respirable coal mine dust at the mine exceeds 5%.  When the quartz content of the respirable dust exceeds 5% in a coal mine sample, the MSHA PEL is reduced based on the following formula:

The OSHA PEL of 2 fibers per cubic centimeter (f/cc) for asbestos was reduced to 0.2 f/cc on July 21, 1986, and to 0.1 f/cc on October 11, 1994. Therefore, asbestos exposures are reported for three time periods: 1979–1986, 1987–1994, and 1994–2003. The MSHA PEL for asbestos has not changed from 2 f/cc since it was adopted.

The OSHA PELs for cotton dust (raw) vary by processing operation. They are:
•   1 mg/m3 for the cotton waste processing operations of waste recycling (sorting, blending, cleaning, and willowing) and garneting;
•   0.75 mg/m3 for textile slashing and weaving operations;
•   0.50 mg/m3 for textile mill waste house operations or for dust from “lower grade washed cotton” used during yarn manufacturing; and
•   0.20 mg/m3 for yarn manufacturing and cotton washing operations.

Reporting of cotton dust data began when the process-specific OSHA PELs became effective on March 27, 1980.

Recommended Exposure Limits. NIOSH develops and periodically revises recommended exposure limits (RELs) for hazardous substances or conditions in the workplace. The RELs are then published and transmitted to OSHA and MSHA for use in promulgating legal standards. The RELs for mineral dusts and chemical hazards, including pneumoconiotic agents, are published in the NIOSH Pocket Guide to Chemical Hazards (NIOSH Pub. No. 2005-149). The REL for coal mine dust was adopted in September 1995, while RELs for the other pneumoconiotic agents in this report were adopted before 1979, which is the first year OSHA and MSHA data are reported. The REL for beryllium and compounds is based on cancer, rather than pneumoconiotic effects. NIOSH has no full-shift RELs for the following pneumoconiotic agents: aluminum oxide, emery, synthetic graphite, rouge, fused respirable silica dust, titanium dioxide, and welding fumes (total particulate).

Data Selection
MSHA coal mine dust.  MSHA coal mine dust samples included in this report met all of the following criteria:
(1) obtained in the U.S. or one of its territories;
(2) designated by MSHA as valid;
(3) coded as “designated occupation,” “non-designated occupation,” “designated work position,” “non-designated work position” with valid occupation codes, or “designated area” other than “intake air”;
(4) not an optional operator sample.

MSHA Coal Mine Quartz. Coal mine quartz data included in this report were obtained from MSHA.  The MSHA Teradata Query System (often used by other investigators) only includes some specific samples sent from the Pittsburgh database for special analysis prompted by specific actions.  Coal mine quartz samples included in this report met all of the following criteria:
(1) obtained in the U.S. or one of its territories;
(2) designated by MSHA as valid;
(3) sample duration greater than zero;
(4) quartz content greater than or equal to zero;
(5) coded as “designated occupation,” “non-designated occupation,” “designated work position,” “non-designated work position” with valid occupation codes, or “designated area” other than “intake air”;
(6) not an optional operator sample.

MSHA Metal/Nonmetal Mine Data (MNMD). MSHA metal/nonmetal mine data (MNMD) included in this report met the following criteria:
(1) obtained in the U.S. or one of its territories;
(2) not duplicated by another record, as determined by a comparison of all data fields.

NIOSH staff edited the MNMD provided by MSHA to remove duplicate records and records with internal inconsistencies, similarly to the methods previously used by the U.S. Bureau of Mines for data presented in WoRLD Report editions published prior to 2002.

The respirable quartz exposure data in the Silicosis and Related Exposures section includes the following MSHA respirable dust contaminant codes: 121 (listed nuisance dust, respirable fraction, less than 1% silica), 131 (unlisted dust, respirable fraction, less than 1% silica), 521 (respirable dust, quartz fraction not analyzed), and 523 (quartz, respirable crystalline silica fraction, greater than or equal to 1% quartz).  Codes 121, 131, 521, and 523 are all respirable silica dust personal air samples.  The specific code is assigned based on the laboratory's analytical result, matched to the definition of the code.

OSHA Integrated Management Information System (IMIS). IMIS samples included in this report met all of the following criteria:
(1) the state code was one of the 50 U.S. states, Washington, DC, American Samoa, Guam, Puerto Rico, or the U.S. Virgin Islands;
(2) the sample type was “area” or “personal” (excludes: “bulk,” “wipe,” “screen,” “blood,” and “urine” samples);
(3) the exposure type was “time-weighted average,” or “not detected” (excludes: “ceiling,” “peak,” “dose,” “sound reading,” “not analyzed,” and “not valid”);
(4) the indicated OSHA PEL and units were applicable to the contaminant indicated by the substance code for the recorded date of sampling.

Data Analysis for MSHA and OSHA Samples
The reported number of samples for an agent was the total number of samples meeting the above criteria. The percent of samples exceeding the PEL for an agent category was calculated as the number of samples in that category with measured exposures exceeding the PEL enforced at the time the sample was collected, divided by the total number of samples for the agent, and finally multiplying by 100. The percent of samples exceeding the REL for an agent was calculated as the number of samples in that category with measured exposure exceeding the REL, divided by the total number of samples for the agent, and multiplying by 100.

Exposures are commonly log normally distributed, rather than normally distributed. For this reason geometric mean exposures are presented in this report. To calculate a geometric mean exposure, samples less than the minimum quantifiable concentration (MQC) were assigned a value, either the (MQC/2) or (MQC/√2), depending on the distribution of samples that were quantifiable.³  The analytical methods used to calculate the MQC for selected pneumoconiotic agents are presented in Appendix F. The calculation assumes a sample duration of 6 hours for cotton dust and 7 hours for other agents.

The OSHA and MSHA asbestos MQCs changed during the 1979–2003 period; therefore, appropriate MQCs were used for each time period.

The limit of detection of 10 micrograms was determined by the sensitivity of the balance. Results for cotton dust samples below the MQC (3.5% of all cotton dust samples) could not be assigned to a specific cotton dust processing operation and were not included in the Byssinosis and Related Exposures section.

The MSHA respirable coal mine quartz data are based on analyses of respirable coal mine dust samples. Not every respirable coal mine dust sample is analyzed for quartz. Therefore, in the Coal Workers' Pneumoconiosis and Related Exposures section, the percent of respirable coal mine dust samples exceeding the MSHA PEL were calculated using the MSHA PEL of 2 mg/m3 MRE for respirable coal mine dust containing no more than 5% quartz.

For the MSHA respirable coal mine quartz data, the quartz concentration is used in calculating the geometric means.  The quartz concentration is calculated using the formula:

In the Silicosis and Related Exposures section the geometric means of exposure to quartz are reported for OSHA samples. However, the reported percentage exceeding the PEL compares only the respirable dust samples containing at least 1% quartz to the PEL for respirable dust containing at least 1% quartz. The exception is from March 1, 1989 through March 22, 1993, when OSHA enforced a PEL of 0.1 mg/m3 for respirable quartz. During this period the percentage greater than the PEL compares the exposure to quartz to 0.1 mg/m3. 

Industries with Elevated PMRs and Most Frequently Recorded on Death Certificates
This report includes number of samples, geometric mean exposures, and percent of samples exceeding the PEL or REL by selected industries for exposure agents related to elevated occupational lung disease mortality. For asbestosis, CWP, silicosis, byssinosis, and all pneumoconiosis, separate tables present data for the ten most frequently recorded industries with five or more decedents and significantly elevated PMRs.  [Note: see industry/occupation titles below.]

STATE AND COUNTY DESIGNATIONS

The “number of states” displayed on maps in this report sums to 51 because the District of Columbia is included.  Counties in this report are coded according to the 1990 Federal Information Processing Standards (FIPS) Codes system. A small number of counties or county equivalents have split, merged with, or separated from surrounding or adjacent subdivisions (see Appendix H). Readers should be cautious in assessing geographic patterns and temporal trends for subdivisions that have split or merged.

INDUSTRY/OCCUPATION
CODES AND TITLES

Since 1993, the 1990 Bureau of Census (BoC) Index of Industries and Occupations classification system has been used for coding death certificate information on the NCHS multiple cause-of-death data files.  Most codes and titles in the 1990 system do not differ from the 1980 system.  All tables reporting BoC industry (CIC) and occupation (COC) codes and titles that are presented in the mortality and exposure sections of this report, except those listed in Appendix D, follow the 1980 BoC classification system.  For more information: Technical Appendix for 1998 at http://www.cdc.gov/nchs/about/major/dvs/mcd/1998mcd.htm and pages XI-XIV in U.S. Dept. Commerce  1992,  Alphabetical Index of Industries and Occupations,  Bureau of the Census, 1990 CPH-R-3.

NIOSH established the National Occupational Research Agenda (NORA) as a partnership program to stimulate innovative research and improved workplace practices (see http://www.cdc.gov/niosh/nora/default.html).  To assign CIC codes to NORA Sector Groups (see http://www.cdc.gov/niosh/nora/sector.html), the CIC codes were merged using crosswalks available at http://www.census.gov/hhes/www/ioindex/indcswk2k.pdf and http://www.census.gov/epcd/naics02/NAICS97toNAICS02.xls.  The CIC codes are listed by NORA Sector Group in Appendix I.

Industry/occupation titles ranked by estimated prevalence of asthma, COPD, and smoking, which are presented in the morbidity sections of this report, had been classified according to the 1995 SIC System and then regrouped by the NCHS.  Industry-specific incidence rates of the pneumoconioses and respiratory conditions due to toxic agents follow the 1987 SIC System. Tables summarizing temporal patterns of geometric mean exposures in selected sections (i.e., asbestos, silica, and pneumoconiotic agents) of this report also group industries by the 1987 SIC System.

The primary industries associated with silicosis and work-related asthma cases in the Sentinel Event Notification System for Occupational Risks (SENSOR) sections of this report are grouped by the 1987 SIC System.  However, the correspondent primary occupations are grouped by the 1990 BoC classification system (COC). In this report, industries/occupations associated with five or more silicosis or with 10 or more work-related asthma cases are listed. Industries/occupations associated with less than five silicosis or with less than 10 work-related asthma cases are aggregated in an "All other" category.