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Coal Workers' Health Surveillance Program (CWHSP) Data Query System

The CWHSP is a federally mandated worker medical monitoring program for underground coal miners. Its intent is to prevent early coal workers' pneumoconiosis (CWP) from progressing to disabling disease. Eligible miners can obtain periodic chest radiographs. Miners found to have radiographic evidence of CWP are advised of this and are provided, by law, the opportunity to work in a 'low-dust' occupation in the mine. The program is operated by the National Institute for Occupational Safety and Health (NIOSH), which has maintained data from this program since its inception in 1970. The data can be queried to produce tables and maps using the interactive system below. The x-rays included in this system encompass x-rays from the Coal Workers' X-ray Surveillance Program (CWXSP) and the Enhanced Coal Workers' Health Surveillance Program (ECWHSP). The CWXSP also includes x-rays from the National Coal Study (also known as the National Study of Coal Workers' Pneumoconiosis) and the Miners' Choice Health Screening Program. New data will be added annually, and due to the dynamic nature of data collection, which includes error correction and the addition of missing information, query system data are subject to change. Further information about the program is available on the CWHSP home page.

The underlying data contain confidential information. In order to protect the privacy of individual miners, NIOSH cannot release the underlying data.

The query system uses the last x-ray available for an individual within the selected time period. This means that the number of x-rays for any selected time period will generally be less than the sum derived from separate queries undertaken for partial time periods included within the overall selected time period. For example, the total number of x-rays for a query of the 1970 – 79 period is less than the sum of the numbers for queries of 1970 – 74 and 1975 – 79 because, for the 1970 – 79 query, only the most recent x-ray was considered for those miners examined in both 1970 – 74 and 1975 – 79. The reason for this procedure is to ensure that findings for each individual are included only once in any selected time period.

This application generates tables of CWP prevalence (n and %), by severity categories and by cumulative severity categories, for subsets of CWHSP data defined by query-specified demographic and geographical criteria. Severity Categories are determined from an x-ray's final determination (based on multiple radiographic readings using a standardized algorithm) using the International Labour Office (ILO) large opacity category (A, B, or C) and small opacity profusion category (0, 1, 2, or 3). ILO category A, B, or C represents PMF (progressive massive fibrosis), the most severe form of CWP. ILO category 1, 2, and 3 represent CWP of lesser severities.

CWP Severity Categories:

  • PMF = evidence of the most severe form of CWP. PMF is complicated CWP.
  • 1, 2, and 3 = evidence of CWP, with severity increasing from ILO category 1 to 3.
  • 0 = No clear evidence of CWP

Cumulative CWP Severity Categories:

  • PMF = CWP Severity Category PMF
  • 3+ = CWP Severity Categories 3 and PMF
  • 2+ = CWP Severity Categories 2, 3, and PMF
  • 1+ = CWP Severity Categories 1, 2, 3, and PMF

Further information on how CWP is classified can be found at Chest Radiography.

Two figures are generated for each mapping query:

  • A map showing the number of examined miners in the query-specified Cumulative CWP Severity Category and query-specified geographic areas
  • A map showing the percentage of examined miners in the query-specified Cumulative CWP Severity Category and query-specified geographic areas

Certain restrictions have been placed on the queries to protect the privacy of individual miners. Data are not listed for any district, state, or county with less than 10 examined miners. County-level queries are only generated for all ages (15 and older) and all tenures (0 to 40+). Data are reported by 5-year periods (or multiples of 5) because the surveillance program runs in 5-year cycles. Data are reported by 10-year periods (or multiples of 10) when age or tenure subsets are queried at the state or district level. Queries by MSHA District, state, and/or county are not allowed for combined programs, mine types, employment status, or type of employer.

Maps of individual states will automatically default to county outlines. Maps of MSHA Districts are not available for miners' place of residence. Decreasing the viewport width of your browsers' window after generating a map will adversely affect the location of mouseover pop-ups.

A field with an asterisk (*) before it is a required field. All other fields are preselected with a default option.

CWHSP Data Query System Fields

Display Type:
Cumulative CWP Severity Category for maps:
Produce maps that may be viewed more easily by individuals with:
Overall or by state or county:
Overall or by county:
Geopolitical boundaries for the map:
Sort the Output:
Select MSHA District:
   MSHA assigns a mine to a district based on workload and proximity to a district field office. With this assignment, some of the mines fall outside the district boundary. To reflect the geographical location of the mine, NIOSH assigned districts according to the MSHA District map by state and county.
Mine Types (please note that all three Mine Types are selected by default):
Mine Types (select one):
Miners' Employment Status at Time of Participation:
Type of Employer:
Age or Tenure Selection Criteria:
Age Group (years):
Tenure Group (years):
Submit Query