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Thursday, 17 March 2011 18:14

Development and Application of an Occupational Injury and Illness Classification System

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Systems of workplace injury and illness surveillance constitute a critical resource for management and reduction of occupational injuries and illnesses. They provide essential data which can be used to identify workplace problems, develop corrective strategies and thus prevent future injuries and illnesses. To accomplish these goals effectively, surveillance systems must be constructed which capture the characteristics of workplace injuries in considerable detail. To be of maximum value, such a system should be able to provide answers to such questions as which workplaces are the most hazardous, which injuries produce the most time lost from work and even what part of the body is injured most frequently.

This article describes the development of an exhaustive classification system by the Bureau of Labor Statistics of the United States Department of Labor (BLS). The system was developed to meet the needs of a variety of constituencies: state and federal policy analysts, safety and health researchers, employers, employee organizations, safety professionals, the insurance industry and others involved in promoting safety and health in the workplace.

Background

For a number of years, the BLS has collected three basic types of information concerning an occupational injury or illness:

  • industry, geographic location of the incident and any associated lost workdays
  • characteristics of the affected employee, such as age, gender and occupation
  • how the incident or exposure occurred, the objects or substances involved, the nature of the injury or illness and part of the body affected.

 

The previous classification system, though useful, was somewhat limited and did not fully meet the needs described above. In 1989 it was decided that a revision of the existing system was in order that would best suit the needs of the varied users.

The Classification System

A BLS task force was organized in September 1989 to establish requirements for a system that would “accurately describe the nature of the occupational safety and health problem” (OSHA 1970). This team worked in consultation with safety and health specialists from the public and private sectors, with the goal of developing a revamped and expanded classification system.

Several criteria were established governing the individual code structures. The system must have a hierarchical arrangement to allow maximum flexibility for varied users of occupational injury and illness data. The system should be, to the extent possible, compatible with the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) of the WHO (1977). The system should meet the needs of other government agencies involved in the safety and health arena. Finally, the system must be responsive to the differing traits of nonfatal and fatal cases.

Drafts of the case characteristic classification structures were produced and released for comment in 1989 and again in 1990. The system included nature of injury or illness, part of body affected, source of injury or illness, event or exposure structures and secondary source. Comments were received and incorporated from bureau staff, state agencies, Occupational Safety and Health Administration, Employment Standards Administration and NIOSH, after which the system was ready for an onsite test.

Pilot testing of the structures for compiling data for nonfatal injuries and illnesses, as well as the operational application in the Census of Fatal Occupational Injuries, was conducted in four states. Test results were analysed and revisions completed by the fall of 1991.

The final 1992 version of the classification system consists of five case characteristic code structures, an occupational code structure and an industry code structure. The Standard Industrial Classification Manual is used to classify industry (OMB 1987), and the Bureau of the Census Alphabetical Index of Occupations for coding occupation (Bureau of the Census 1992). The BLS Occupational Injury and Illness Classification System (1992) is used to code the following five characteristics:

  • nature of injury or illness
  • part of body affected
  • event or exposure
  • source of injury or illness
  • secondary source of injury or illness.

Besides numerical codes that represent specific conditions or circumstances, each code structure includes aids to assist in identification and selection of the proper code. These aids include: definitions, rules of selection, descriptive paragraphs, alphabetical listings and edit criteria for each of the structures. The rules of selection offer guidance to choose the appropriate code uniformly when two or more code selections are possible. The descriptive paragraphs provide additional information about the codes such as what is included or excluded in a particular code. For instance, the code for eye includes the eyeball, the lens, the retina and the eyelashes. The alphabetical listings can be used to quickly find the numerical code for a specific characteristic, such as medical terminology or specialized machinery. Finally, edit criteria are quality-assurance tools that can be used to determine which code combinations are incorrect prior to final selection.

Nature of injury or illness codes

The nature of injury or illness code structure describes the principal physical characteristic of the worker’s injury or illness. This code serves as the basis for all other case classifications. Once the nature of injury or illness has been identified, the remaining four classifications represent the circumstances associated with that particular outcome. The classification structure for nature of injury of illness contains seven divisions:

  • traumatic injuries and disorders
  • systemic diseases or disorders
  • infectious and parasitic diseases
  • neoplasms, tumours and cancer
  • symptoms, signs and ill-defined conditions
  • other conditions or disorders
  • multiple diseases, conditions or disorders.

 

Before finalizing this structure, two similar classifications systems were evaluated for possible adoption or emulation. Because the American National Standards Institute (ANSI) Z16.2 standard (ANSI 1963) was developed for use in accident prevention, it does not contain a sufficient number of illness categories for many agencies to accomplish their missions.

The ICD-9-CM, designed for classifying morbidity and mortality information and used by a large portion of the medical community, provides the required detailed codes for illnesses. However, technical knowledge and training requirements for users and compilers of these statistics made this system prohibitive.

The final structure arrived at is a hybrid which combines the application method and rules of selection from the ANSI Z16.2 with the basic divisional organization from the ICD-9-CM. With few exceptions, divisions in the BLS structure can be directly mapped to the ICD-9-CM. For example, the BLS division identifying infectious and parasitic diseases maps directly to Chapter 1, Infectious and Parasitic Diseases, of the ICD-9-CM.

The first division in the BLS nature of injury or illness structure classifies traumatic injuries and disorders, effects of external agents and poisoning, and corresponds to Chapter 17 of the ICD-9-CM. Outcomes in this division are generally the result of a single incident, event or exposure, and include conditions such as fractures, bruises, cuts and burns. In the occupational environment, this division accounts for the great majority of reported cases.

Several situations required careful consideration when establishing rules to select codes in this division. Review of fatality cases revealed difficulties in coding certain types of fatal injuries. For example, fatal fractures usually involve direct or indirect mortal damage to a vital organ, such as the brain or spinal column. Specific coding categories and instructions were required to note the mortal damage associated with these types of injuries.

Gunshot wounds constitute a separate category with special instructions for those instances in which such wounds also resulted in amputations or paralysis. In keeping with an overall philosophy of coding the most serious injury, paralysis and amputations take precedence over less serious damage from a gunshot wound.

Responses to questions on employer reporting forms concerning what happened to the injured or ill worker do not always adequately describe the injury or illness. If the source document indicates only that the employee “hurt his back”, it is not appropriate to assume this is a sprain, strain, dorsopathy or any other specific condition. To solve the problem, individual codes were established for non-specific descriptions of injury or illness like “sore,” “hurt” and “pain”.

Finally, this division has a section of codes to classify the most frequently occurring combinations of conditions that result from the same incident. For example, a worker may suffer both scratches and bruises from a single incident.

Five of the remaining divisions of this classification structure were devoted to identification of occupational diseases and disorders. These sections present codes for specific conditions that are of paramount interest to the safety and health community. In recent years, a growing number of diseases and disorders have been linked to the work environment but were seldom represented in the existing classification structures. The structure has a vastly expanded list of specific diseases and disorders such as carpal tunnel syndrome, Legionnaire’s disease, tendonitis and tuberculosis.

Part of body affected

The part of body affected classification structure specifies the part of the body which was directly affected by the injury or illness. When linked with the nature of injury or illness code, it provides a more complete picture of the damage incurred: amputated finger, lung cancer, fractured jaw. This structure consists of eight divisions:

  • head
  • neck, including throat
  • trunk
  • upper extremities
  • lower extremities
  • body systems
  • multiple body parts
  • other body parts.

 

Three issues surfaced during evaluation of redesign options for this theoretically simple and straightforward piece of the classification system. The first was the merit of coding external location (arm, trunk, leg) of the injury or illness versus the affected internal site (heart, lungs, brain).

Test results indicated that coding the internal part of body affected was appropriate for diseases and disorders, but extremely confusing when applied to many traumatic injuries such as cuts or bruises. The BLS developed a policy of coding the external location for most traumatic injuries and coding internal locations, where appropriate, for diseases.

The second issue was how to handle diseases that affect more than one body system simultaneously. For instance, hypothermia, a condition of low body temperature due to exposure to the cold, can affect the nervous and endocrine systems. Because it is difficult for nonmedical personnel to determine which is the appropriate choice, this could lead to a tremendous amount of research time with no clear resolution. Therefore, the BLS system was designed with a single entry, body systems, that categorizes one or more body systems.

Adding detail to identify typical combinations of parts in the upper extremities and the lower extremities was the third major enhancement to this code structure. These combinations, such as hand and wrist, proved to be supportable by the source documents.

Event or exposure

The event or exposure code structure describes the manner in which the injury or illness was inflicted or produced. The following eight divisions were created to identify the primary method of injury or exposure to a harmful substance or situation:

  • contact with objects and equipment
  • falls
  • bodily reaction and exertion
  • exposure to harmful substances or environments
  • transportation accidents
  • fires and explosions
  • assaults and violent acts
  • other events or exposures.

Injury-producing incidents are frequently composed of a series of events. To illustrate, consider what occurs in a traffic accident: A car hits a guard-rail, crosses the median strip and collides with a truck. The driver has several injuries from striking parts of the car and being struck by broken glass. If the micro-events—such as hitting the windshield or being struck by flying glass—were coded, the overall fact that the person was in a traffic accident could be missed.

In these multiple event instances, the BLS designated several occurrences to be considered primary events and to take precedence over other micro-events associated with them. These primary events included:

  • assaults and violent acts
  • transportation accidents
  • fires
  • explosions.

An order of precedence was established within these groups as well because they frequently overlap—for example, a highway accident can involve a fire. This order of precedence is the order which they appear in the above list. Assaults and violent acts were assigned first precedence. Codes within this division generally describe the type of violence, while the weapon is addressed in the source code. Transportation accidents are next in precedence, followed by fires and explosions.

These last two events, fires and explosions, are combined in a single division. Because the two often occur simultaneously, an order of precedence between the two had to be established. In accordance with the ICD-9 Supplementary Classification of External Causes, fires were given precedence over explosions (USPHS 1989).

Selection of codes for inclusion in this structure was influenced by the emergence of non-contact disorders that are associated with the activities and ergonomics of the job. These cases typically involve nerve, muscle or ligament damage brought about by exertion, repetitive motion and even simple body motions such as when the worker’s back “goes out” when reaching over to pick up an item. Carpal tunnel syndrome is now widely recognized to be tied to repetitive actions such as key entry, typing, cutting actions and even operating a cash register. The division bodily reaction and exertion identifies these non-contact, or non-impact, incidents.

The event division “exposure to harmful substances or environments” distinguishes the specific method of exposure to toxic or harmful substances: inhalation, skin contact, ingestion or injection. A separate category to identify the transmission of an infectious agent through a needle stick was developed. Also included in this division are other non-impact incidents in which the worker was harmed by electric power or by environmental conditions, such as extreme cold.

Contact with objects and equipment and falls are the divisions that will capture most impact events that injure workers.

Source of injury or illness

The source of injury or illness classification code identifies the object, substance, bodily motion or exposure which directly produced or inflicted the injury or illness. If a worker is cut on the head by a falling brick, the brick is the source of injury. There is a direct relationship between the source and the nature of the injury or illness. If a worker slips on oil and falls to the floor, breaking an elbow, the fracture is produced by hitting the floor, so the floor is source of injury. This code system contains ten divisions:

  • chemicals and chemical products
  • containers
  • furniture and fixtures
  • machinery
  • parts and materials
  • persons, plants, animals and minerals
  • structures and surfaces
  • tools, instruments and equipment
  • vehicles
  • other sources.

The general definitions and coding concepts for the new BLS Source Classification Structure were carried over from the ANSI Z16.2 classification system. However, the task of developing a more complete and hierarchical code listing was initially daunting, since virtually any item or substance in the world can qualify as a source of injury or illness. Not only can everything in the world qualify as source, so can pieces or parts of everything in the world. To add to the difficulty, all candidates for inclusion in the source codes had to be grouped into only ten divisional categories.

Examination of historical data on work injuries and illness identified areas where the previous code structure was inadequate or out of date. The machinery and tools sections needed expansion and updating. There was no code for computers. Newer technology had made the list of power tools obsolete, and many items listed as nonpowered tools were now almost always powered: screwdrivers, hammers and so on. There was a demand from users to expand and update the list of chemicals in the new structure. The US Occupational Safety and Health Administration requested expanded detail for a variety of items, including several types of scaffolds, forklifts and construction and logging machines.

The most difficult aspect of developing the source structure was organizing the items required for inclusion into distinct divisions and groups within the division. To add to the difficulty, the source code categories had to be mutually exclusive. But no matter what categories were developed, there were many items that logically fit in two or more divisions. For example, there was general agreement that there should be separate categories for vehicles and for machines. However, reviewers disagreed about whether certain equipment such as road pavers or forklifts, belonged with machines or vehicles.

Another area of debate developed on how to group the machines within the machinery division. The options included associating machines with a process or an industry (for example, agricultural or garden machines), grouping them by function (printing machines, heating and cooling machinery) or by type of object processed (metal working, woodworking machines). Unable to find a single solution which was workable for all types of machines, the BLS compromised with a listing that uses an industry function for some groups (agricultural machines, construction and logging machines), general function for other groups (material handling machines, office machines), and some material-specific functional groupings (metalworking, woodworking). Where the possibility of overlap occurred, such as a woodworking machine used for construction work, the structure defined the category to which it belonged, to keep the codes mutually exclusive.

Special codes were added to capture information on injuries and illnesses occurring in the health care industry, which has emerged as one of the largest employment sectors in the United States, and one with serious safety and health problems. As an example, many of the participating state agencies recommended inclusion of a code for patients and residents of health care facilities, since nurses and health aides can be hurt while trying to lift, move or otherwise care for their patients.

Secondary source of injury or illness

The BLS and other data users recognized that the occupational injury and illness source classification structure captures the object that produced the injury or illness but sometimes fails to identify other important contributors to the event. In the previous system, for example, if a worker was struck by a piece of wood that flew off a jammed saw, the wood was the source of injury; the fact that a power saw was involved was lost. If a worker was burned by fire, the flame was selected as the source of injury; one could not also identify the source of the fire.

To make up for this potential loss of information, the BLS developed a secondary source of injury or illness which “identifies the object, substance, or person that generated the source or injury or illness or that contributed to the event or exposure”. Within the specific rules of selection for this code, the emphasis is on identifying the machines, tools, equipment or other energy-generating substances (such as flammable liquids) that are not identified through source classification. In the first example noted above, the power saw would be the secondary source, since it threw out the piece of wood. In the latter example, the substance that ignited (grease, gasoline and so on) would be named as the secondary source.

Implementation Requirements: Review, Verification and Validation

Establishing a comprehensive classification system is only one step in assuring that accurate information concerning workplace injuries and illnesses is captured and available for use. It is important that workers in the field understand how to apply the coding system accurately, uniformly and according to the system design.

The first step in quality assurance was to thoroughly train those who will be assigning the classification system codes. Beginning, intermediate and advanced courses were developed to assist in uniform coding techniques. A small group of trainers was charged with delivering these courses to concerned personnel throughout the United States.

Electronic edit checks were devised to assist in the review, verification and validation process for the case characteristic and demographic estimates. Criteria of what can and cannot be combined were identified and an automated system to identify those combinations as errors was put into place. This system has over 550 groups of cross check which verify that the incoming data meet quality checks. For example, a case that identified carpal tunnel syndrome as affecting the knee would be deemed an error. This automated system also identifies invalid codes, that is, codes that do not exist in the classification structure.

Clearly, these edit checks cannot be sufficiently stringent to capture all suspect data. The data should be examined for overall reasonableness. For example, over the years of collecting similar data for the part of body, nearly 25% of the cases named the back as the affected area. This gave review staff a benchmark for validating data. A review of cross tabulations for overall sensibility also gives insight into how well the classification system was applied. Finally, special rare events, such as work-related tuberculosis, should be validated. One important element of a comprehensive validation system could involve recontacting the employer to insure the accuracy of the source document, although this requires additional resources.

Examples

Selected examples from each of the four illness and injury classification coding systems are shown in table 1 in order to illustrate the level of detail and the resulting richness of the final system. The power of the system as a whole is demonstrated in table 2, which shows a variety of characteristics that were tabulated for one set of related injury types—falls. In addition to total falls, the data are further subdivided into falls on the same level, falls to a lower level and jumping to a lower level. It can be seen, for instance, that falls were most likely to occur to workers age 25 to 34 years old, to operators, fabricators and labourers, to workers in the manufacturing industries and to workers with less than five years of service to their current employer (data not shown). The accident was most often associated with work on a floor or ground surface, and the subsequent injury was most likely to be a sprain or strain affecting the back, resulting in the worker spending more than one month away from work.

 


Table 1. Nature of injury or illness code—Examples

 

Nature of injury or illness code-Examples

0* Traumatic Injuries and Disorders

08*                                    Multiple traumatic injuries and disorders

080                              Multiple traumatic injuries and disorders, unspecified

081                              Cuts, abrasions, bruises

082                              Sprains and bruises

083                              Fractures and burns

084                              Fractures and other injuries

085                              Burns and other injuries

086                              Intracranial injuries and injuries to internal organs

089                              Other combinations of traumatic injuries and disorders, n.e.c.

Event or exposure code-Examples

1* Falls

11*                                   Fall to lower level

113                              Fall from ladder

114                              Fall from piled or stacked material

115*                            Fall from roof

1150                  Fall from roof, unspecified

1151                  Fall through existing roof opening

1152                  Fall through roof surface

1153                  Fall through skylight

1154                  Fall from roof edge

1159                  Fall from roof, n.e.c.

116                    Fall from scaffold, staging

117                    Fall from building girders or other structural steel

118                    Fall from nonmoving vehicle

119                    Fall to lower level, n.e.c.

Source of injury or illness code-Examples

7*Tools, instruments and equipment

72*                                     Handtools-powered

722*                              Cutting handtools, powered

7220                   Cutting handtools, powered, unspecified

7221                   Chainsaws, powered

7222                   Chisels, powered

7223                    Knives, powered

7224                    Saws, powered, except chainsaws

7229                    Cutting handtools, powered, n.e.c.

723*                               Striking and nailing handtools, powered

7230                    Striking handtools, powered, unspecified

7231                    Hammers, powered

7232                    Jackhammers, powered

7233                    Punches, powered

Part of body affected code-Examples

2* Trunk

23*                                   Back, including spine, spinal cord

230                              Back, including spine, spinal cord, unspecified

231                              Lumbar region

232                              Thoracic region

233                              Sacral region

234                              Coccygeal region

238                              Multiple back regions

239                              Back, including spine, spinal cord, n.e.c.

* = division, major group, or group titles; n.e.c. = not elsewhere classified.


 

Table 2. Number and percentage of nonfatal occupational injuries and illnesses with days away from work involving falls, by selected worker and case characteristics, US 19931

Characteristic

All events

All falls

Fall to lower level

Jump to lower level

Fall on same level

 

Number

%

Number

%

Number

%

Number

%

Number

%

Total

2,252,591

100.0

370,112

100.0

111,266

100.0

9,433

100.0

244,115

100.0

Sex:

Men

1,490,418

66.2

219,199

59.2

84,868

76.3

8,697

92.2

121,903

49.9

Women

735,570

32.7

148,041

40.0

25,700

23.1

645

6.8

120,156

49.2

Age:

14 to 15 years

889

0.0

246

0.1

118

0.1

84

0.0

16 to 19 years

95,791

4.3

15,908

4.3

3,170

2.8

260

2.8

12,253

5.0

20 to 24 years

319,708

14.2

43,543

11.8

12,840

11.5

1,380

14.6

28,763

11.8

25 to 34 years

724,355

32.2

104,244

28.2

34,191

30.7

3,641

38.6

64,374

26.4

35 to 44 years

566,429

25.1

87,516

23.6

27,880

25.1

2,361

25.0

56,042

23.0

45 to 54 years

323,503

14.4

64,214

17.3

18,665

16.8

1,191

12.6

43,729

17.9

55 to 64 years

148,249

6.6

37,792

10.2

9,886

8.9

470

5.0

27,034

11.1

65 years and over

21,604

1.0

8,062

2.2

1,511

1.4

24

0.3

6,457

2.6

Occupation:

Managerial and professional

123,596

5.5

26,391

7.1

6,364

5.7

269

2.9

19,338

7.9

Technical, sales and 
administrative support

344,402

15.3

67,253

18.2

16,485

14.8

853

9.0

49,227

20.2

Service

414,135

18.4

85,004

23.0

13,512

12.1

574

6.1

70,121

28.7

Farming, forestry and fishing

59,050

2.6

9,979

2.7

4,197

3.8

356

3.8

5,245

2.1

Precision production, craft 
and repair

366,112

16.3

57,254

15.5

27,805

25.0

1,887

20.0

26,577

10.9

Operators, fabricators and 
labourers

925,515

41.1

122,005

33.0

42,074

37.8

5,431

57.6

72,286

29.6

Nature of injuries, illness:

Sprains, strains

959,163

42.6

133,538

36.1

38,636

34.7

5,558

58.9

87,152

35.7

Fractures

136,478

6.1

55,335

15.0

21,052

18.9

1,247

13.2

32,425

13.3

Cuts, lacerations punctures

202,464

9.0

10,431

2.8

2,350

2.1

111

1.2

7,774

3.2

Bruises, contusions

211,179

9.4

66,627

18.0

17,173

15.4

705

7.5

48,062

19.7

Multiple injuries

73,181

3.2

32,281

8.7

11,313

10.2

372

3.9

20,295

8.3

With fractures

13,379

0.6

4,893

1.3

2,554

2.3

26

0.3

2,250

0.9

With sprains

26,969

1.2

15,991

4.3

4,463

4.0

116

1.2

11,309

4.6

Soreness, Pain

127,555

5.7

20,855

5.6

5,614

5.0

529

5.6

14,442

5.9

Back pain

58,385

2.6

8,421

2.3

2,587

2.3

214

2.3

5,520

2.3

All other

411,799

18.3

50,604

13.7

15,012

13.5

897

9.5

33,655

13.8

Part of body affected:

Head

155,504

6.9

13,880

3.8

2,994

2.7

61

0.6

10,705

4.4

Eye

88,329

3.9

314

0.1

50

0.0

11

0.1

237

0.1

Neck

40,704

1.8

3,205

0.9

1,097

1.0

81

0.9

1,996

0.8

Trunk

869,447

38.6

118,369

32.0

33,984

30.5

1,921

20.4

80,796

33.1

Back

615,010

27.3

72,290

19.5

20,325

18.3

1,523

16.1

49,461

20.3

Shoulder

105,881

4.7

16,186

4.4

4,700

4.2

89

0.9

11,154

4.6

Source of injury illness:

Chemicals, chemical 
products

43,411

1.9

22

0.0

16

0.0

Containers

330,285

14.7

7,133

1.9

994

0.9

224

2.4

5,763

2.4

Furniture, fixtures

88,813

3.9

7,338

2.0

881

0.8

104

1.1

6,229

2.6

Machinery

154,083

6.8

4,981

1.3

729

0.7

128

14

4,035

1.7

Parts and materials

249,077

11.1

6,185

1.7

1,016

0.9

255

2.7

4,793

2.0

Worker motion or position

331,994

14.7

Floor, ground surfaces

340,159

15.1

318,176

86.0

98,207

88.3

7,705

81.7

208,765

85.5

Handtools

105,478

4.7

727

0.2

77

0.1

41

0.4

600

0.2

Vehicles

157,360

7.0

9,789

2.6

3,049

2.7

553

5.9

6,084

2.5

Health care patient

99,390

4.4

177

0.0

43

0.0

8

0.1

90

0.0

All other

83,813

3.7

15,584

4.2

6,263

5.6

414

4.4

7,741

3.2

Industry division:

Agriculture, forestry and 
fishing2

44,826

2.0

8,096

2.2

3,636

3.3

301

3.2

3,985

1.6

Mining3

21,090

0.9

3,763

1.0

1,757

1.6

102

1.1

1,874

0.8

Construction

204,769

9.1

41,787

11.3

23,748

21.3

1,821

19.3

15,464

6.3

Manufacturing

583,841

25.9

63,566

17.2

17,693

15.9

2,161

22.9

42,790

17.5

Transportation and public 
utilities3

232,999

10.3

38,452

10.4

14,095

12.7

1,797

19.0

21,757

8.9

Wholesale trade

160,934

7.1

22,677

6.1

8,119

7.3

1,180

12.5

12,859

5.3

Retail trade

408,590

18.1

78,800

21.3

15,945

14.3

1,052

11.1

60,906

24.9

Finance, insurance and 
real estate

60,159

2.7

14,769

4.0

5,353

4.8

112

1.2

9,167

3.8

Services

535,386

23.8

98,201

26.5

20,920

18.8

907

9.6

75,313

30.9

Number of days away from work:

Cases involving 1 day

366,054

16.3

48,550

13.1

12,450

11.2

1,136

12.0

34,319

14.1

Cases involving 2 days

291,760

13.0

42,912

11.6

11,934

10.7

1,153

12.2

29,197

12.0

Cases involving 3-5 days

467,001

20.7

72,156

19.5

20,167

18.1

1,770

18.8

49,329

20.2

Cases involving 6-10 days

301,941

13.4

45,375

12.3

13,240

11.9

1,267

13.4

30,171

12.4

Cases involving 11-20 days

256,319

11.4

44,228

11.9

13,182

11.8

1,072

11.4

29,411

12.0

Cases involving 21-30 days

142,301

6.3

25,884

7.0

8,557

7.7

654

6.9

16,359

6.7

Cases involving 31 or more 
days

427,215

19.0

91,008

24.6

31,737

28.5

2,381

25.2

55,329

22.7

Median days away from work

6 days

 

7 days

 

10 days

 

8 days

 

7 days

 

 1 Days away from work cases include those which result in days away from work with or without restricted work activity.

2 Excludes farms with fewer than 11 employees.

3 Data conforming to OSHA definitions for mining operators in coal, metal, and nonmetal mining and for employers in railroad transportation are provided to BLS by the Mine Safety and Health Administration, U.S. Department of Labor; the Federal Railroad Administration and U.S. Department of Transportation. Independent mining contractors are excluded from the coal, metal, and nonmetal mining industries.

NOTE: Because of rounding and data exclusion of nonclassifiable responses, data may not sum to the totals. Dashes indicate data that do not meet publication guidelines. The survey estimates of occupational injuries and illnesses are based on a scientifically selected sample of employers. The sample used was one of many possible samples, each of which could have produced different estimates. The relative standard error is a measure of the variation in the sample estimates across all possible samples that could have been selected. The percent relative standard errors for the estimates included here range from less than 1 per cent to 58 per cent.
Survey of Occupational Injuries and Illnesses, Bureau of Labor Statistics, US Department of Labor, April 1995.


 

It is clear that data such as these can have an important impact upon development of programmes for work-related accident and disease prevention. Even so, they do not indicate which occupations or industries are the most hazardous, since some very dangerous occupations may have small numbers of workers. Determination of levels of risk associated with particular occupations and industries is explained in the accompanying article “Risk analysis of nonfatal workplace injuries and illnesses”.

 

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