HETA 97-0260-2716

Avondale Shipyards

New Orleans, Louisiana

Max Kiefer

Doug Trout

Marjorie E. Wallace

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports

This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.

Additional HHE reports are available at http://www.cdc.gov/niosh/hhe/reports
ii

PREFACE

The Hazard Evaluations and Technical Assistance Branch of NIOSH conducts field investigations of possible

health hazards in the workplace. These investigations are conducted under the authority of Section 20(a)(6)

of the Occupational Safety and Health Act of 1970, 29 U.S.C. 669(a)(6) which authorizes the Secretary of

Health and Human Services, following a written request from any employer or authorized representative of

employees, to determine whether any substance normally found in the place of employment has potentially

toxic effects in such concentrations as used or found.

The Hazard Evaluations and Technical Assistance Branch also provides, upon request, technical and

consultative assistance to Federal, State, and local agencies; labor; industry; and other groups or individuals

to control occupational health hazards and to prevent related trauma and disease. Mention of company names

or products does not constitute endorsement by the National Institute for Occupational Safety and Health.

ACKNOWLEDGMENTS AND AVAILABILITY OF REPORT

This report was prepared by Max Kiefer and Doug Trout of the Hazard Evaluations and Technical Assistance

Branch, Division of Surveillance, Hazard Evaluations and Field Studies (DSHEFS), and Marjorie E. Wallace

of the Engineering and Control Technology Branch, Division of Physical Sciences and Engineering. Field

assistance was provided by Dave Sylvain, Janie Gittleman, and Sue Ting. Analytical support was provided

by DPSE/ACS. Desktop publishing was performed by Pat Lovell and Nichole Herbert. Review and

preparation for printing was performed by Penny Arthur.

Copies of this report have been sent to employee and management representatives at Avondale and the

OSHA Regional Office. This report is not copyrighted and may be freely reproduced. Single copies will

be available for a period of three years from the date of this report. To expedite your request, include a

self–addressed mailing label along with your written request to:

NIOSH Publications Office

4676 Columbia Parkway

Cincinnati, Ohio 45226

800-356-4674

After this time, copies may be purchased from the National Technical Information Service (NTIS) at

5825 Port Royal Road, Springfield, Virginia 22161. Information regarding the NTIS stock number may be

obtained from the NIOSH Publications Office at the Cincinnati address.

For the purpose of informing affected employees, copies of this report shall be

posted by the employer in a prominent place accessible to the employees for a

period of 30 calendar days.
iii

Health Hazard Evaluation Report 97-0260-2716

Avondale Shipyards

Avondale, Louisiana

November 1998

Max Kiefer

Doug Trout

Marjorie E. Wallace

SUMMARY

On July 9, 1997, the National Institute for Occupational Safety and Health (NIOSH) received a request from the

Machinist Union, New Orleans Metal Trades Council, for a health hazard evaluation (HHE) at the Avondale

Shipyards facility in Avondale, Louisiana. The request indicated that some shipyard employees have experienced

health problems possibly associated with workplace exposures. Potential exposures listed on the request were dust

from sandblasting, welding fumes, contaminants from burning paint, and various solvents associated with

fiberglass work. Reported health effects included breathing problems and nose bleeding.

On August 27, 1997, NIOSH investigators conducted an initial site visit at the Avondale Shipyard to review the

processes and work practices in a large fabrication building referred to as the Factory and the abrasive blasting

building (Shot House). Company environmental monitoring data, the Avondale medical surveillance program for

personnel in the arsenic and lead program, and company accident logs were reviewed. On October 22, 1997,

personal breathing zone (PBZ) air sampling was conducted during the day shift to assess worker exposure to

welding fume in the factory. Bulk samples of both new and recycled grit used in the Shot House were collected

to determine metal composition. During the night shift on October 22 and 23, PBZ samples were collected in the

Shot House to evaluate worker exposure to contaminants generated during abrasive blasting of ship parts. 

Only passive general ventilation had been installed in the Factory. The highest measured welding fume particulate

concentration (55 milligrams per cubic meter [mg/m3

]) was from a worker welding in a confined area (inside an

Inner Bottom Unit) for approximately 1.5 hours. NIOSH recommends controlling exposure to welding fume to

the lowest feasible concentration and meeting the exposure limit for each welding fume constituent. The other four

time-weighted average (TWA) welding fume particulate concentrations ranged from 3.15 mg/m3

 to 19.1 mg/m3.

Measured lead concentrations in the Factory ranged from 0.003 mg/m3

 to 0.010 mg/m3 and were all below the

Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 0.05 mg/m3

. Arsenic

was not detected in any of the samples collected in the Factory.

All workers evaluated in the Shot House wore supplied-air abrasive blasting respirators equipped with a vortex

tube for cooling. The Shot House decontamination trailer had a sound design and, if used properly, should help

reduce the potential for workers to “take home” contaminants such as lead. All measured exposures to iron and

manganese outside the workers’ abrasive blast hoods in the Shot House exceeded the NIOSH recommended

exposure limit (REL) (5.0 mg/m3

 for iron, 1.0 mg/m3 for manganese). Except for one measurement that was

between the analytical limit of detection (LOD) and the limit of quantification (LOQ), all metal concentrations

from samples collected inside the abrasive blast hood were below NIOSH RELs. Assessment of respirator 
iv

performance in the Shot House found that the abrasive blast hoods were performing well. The company’s

biological monitoring of workers in the Shot House includes measurement of total urinary arsenic; this alone is not

an adequate method of assessing workplace arsenic exposure as it does not exclude non-toxic organic arsenic

compounds found in seafood.

Air samples collected outside the abrasive blast hood in the Shot House contain large inertia-driven (rebound)

abrasive grit particles. In samples collected during this evaluation, the large particles contributed over 95% of the

total particulate, iron, and manganese content. Significant levels of lead or arsenic were not detected in the Factory.

The limited medical component of this HHE does not allow NIOSH investigators to draw conclusions concerning

the potential occupational exposures which could account for the respiratory complaints reported in the HHE

request. Concentrations of air contaminants (welding fume in the Factory, total particulate and metals in the Shot

House) higher than those documented in our survey and/or improper use of respiratory protection among exposed

workers are factors that could potentially contribute to respiratory health effects among these workers. Welding

flash burns were the most commonly recorded injury in the Factory, and there is a need to ensure that appropriate

shielding is used to reduce the potential for exposure, of both workers and others in the area, to the welding arc.

Monitored exposures to welding fume components exceeded applicable guidelines in the Factory; with

one exception, respiratory protection worn by Factory welders was sufficiently protective. Measured

exposure during welding in a confined area, even when forced-air ventilation was provided, indicates that

a higher level of respiratory protection is warranted until engineering or work practice controls are

implemented. The source of lead and arsenic contamination in the Shot House is likely the steel grit used

as the abrasive blasting agent. The controls in place during abrasive blasting appeared to adequately

protect workers. Current sampling methodology for abrasive blasting overestimates worker exposure to

lead and other contaminants because non-inhalable abrasive grit enters the filter cassette. Sampling inside

the abrasive blast hood provides a more representative estimate of worker exposure. Recommendations

to help control exposure to welding fume in the Factory are provided in this report.

Keywords: SIC 3731 (Ship Building and Repairing). Abrasive blasting, air sampling, lead, arsenic, welding fume,

ventilation.
TABLE OF CONTENTS

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Acknowledgments and Availability of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Introduction ......................................................................... 1

Background ......................................................................... 1

Factory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Shot House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Methods ........................................................................... 2

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Initial Site Visit ................................................................ 2

Follow-up Site Visit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Welding Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Abrasive Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Bulk Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Evaluation Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Welding Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Abrasive Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Lead . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Industrial Hygiene ................................................................. 8

Factory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Workplace Observations ..................................................... 8

Air Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Shot House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Air Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Respirator Efficacy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Bulk Sampling Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Medical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Records Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Lead Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Welding in the Factory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Safety and Health Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Appendix A: Sampling and Analytical Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Welding Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Abrasive Blasting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Bulk Samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Appendix B: Control of Welding Fume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Movable Hoods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Fume Extraction Guns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Other Welding Fume Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Health Hazard Evaluation Report No. 97-0260-2716 Page 1

INTRODUCTION

In response to a request for a health hazard

evaluation (HHE) received on July 9, 1997, from the

Machinist Union, New Orleans Metal Trades

Council, the National Institute for Occupational

Safety and Health (NIOSH) conducted an initial site

visit on August 27, 1997, and a follow-up survey on

October 21-23, 1997, at the Avondale Shipyards in

Avondale, Louisiana. Dust from sandblasting,

welding fumes, contaminants from burning paint,

and various solvents associated with fiberglass work

were potential exposures listed on the request.

Health problems reported in the request included

breathing problems and nose bleeds. An interim

report describing the actions taken by NIOSH during

the initial site visit, and providing preliminary

findings and recommendations, was issued on

September 23, 1997.

BACKGROUND

Avondale Shipyards encompasses approximately

100 acres on the west bank of the Mississippi river

outside of New Orleans, Louisiana. The shipyard

has been in operation for approximately 60 years and

employs 6000 workers. Most work is completed on

two shifts (7:00 a.m. - 3:30 p.m., 3 p.m. - 11:00

p.m.), with a “skeleton” crew working the 3rd shift

(11:00 p.m. - 7:00 a.m.). The majority of the work at

the shipyard entails construction of naval vessels,

with a smaller component engaged in commercial

vessel construction. Although some ship repair

occurs, most of the work at the shipyard is new

construction. The shipyard has two large floating

dry docks, various production shops and assembly

areas, machine shops, and engineering design

centers.

Factory

The Factory is a 400,000 ft2 facility with four

production lines that add structural components to

plate steel. Prior to the construction of the facility in

1995, these activities were conducted outdoors

without covering. The building is equipped with

large cranes and hydraulic lifts and has a ceiling

height of approximately 65 ft. The northeast side of

the building is connected to the plate shop, and the

other sides have large open panels. Only new

construction occurs in this facility, with the major

activities entailing welding and ship fitting. A red or

gray water-based primer is applied to some of the

metal components for anti-corrosion purposes. No

other painting or fiberglass work occurs in the

factory. Depending on the workload, there can be

from 350 to 500 workers over three shifts assigned to

the factory. The welders are not at fixed locations

and must frequently move about the work area.

There are approximately 35 welding stations per

production line. Welding operations occur in the

Factory area where subsections, subassemblies, and

units are constructed. 

Assembly advances through four separate

departments referred to as Fabrication, Web, CPSU,

and Unit. At the beginning of the process flow, large

steel plates are fabricated into parts for subsections.

These subsections are then joined to fabricate a

larger subassembly. At the final stage of the process

flow, the subassemblies are combined to form large

units. The units are then moved out of the Factory,

inspected and blasted in the Shot House, and then

transported to be joined on board the ship. The

Factory produces approximately 18 units per week.

As work progresses, the sections become more

complex, and welding in confined areas occurs more

frequently.

The primary purpose of constructing the factory was

to provide shade and shelter from adverse weather

conditions. Only passive ventilation was designed in

the factory (ridge vent), and there are no existing

provisions for local or general mechanical exhaust.

According to Avondale Safety and Health

department personnel, welders utilize half-mask airpurifying respirators when working in open areas.

For some specific welding activities (carbon arc

process) in more confined areas, or when there is no

forced air ventilation, employees are required to use

supplied air respirators. Reported employee

concerns include the presence of a haze/smoke in the
Page 2 Health Hazard Evaluation Report No. 97-0260-2716

factory from a build-up of welding emissions, and

inadequate lighting during the night shifts.

To address employee concerns of exposure to

welding emissions, Avondale contracted for an

industrial hygiene evaluation to assess general and

personal exposures in the factory. The evaluation

was conducted over a six-month time frame to

encompass seasonal changes. This survey found that

exposures to various welding-related contaminants

(manganese, total particulate) exceeded permissible

exposure limits during certain welding tasks in semiconfined areas. As a result of this survey, Avondale

safety and health personnel have been investigating

providing mechanical ventilation to reduce

contaminant levels in the factory. 

Shot House

After the assembled ship parts leave the factory, they

are transported to the Blast and Paint building (Shot

House) located on the north side of the factory.

Approximately 50 employees work in this enclosed

building, where abrasive blasting is conducted on the

second shift to remove the primer and prepare the

steel surfaces for painting. Steel shot, or grit,

delivered from two blast pots on each side of the

Shot House is used as the blasting agent; dry blasting

is utilized (no vacuum-assisted or wet blasting). The

building is equipped with forced air ventilation and

a dust collection system. A blast grit recovery

system utilizing floor grates and a conveyor is

present, where used shot is collected and then

separated in the recovery system based on size (fine

and coarse reject); grit meeting the size criteria is

reused. Because of the complexity of the ship parts,

workers must frequently conduct abrasive blasting in

confined areas.

As a result of a company industrial hygiene

investigation that identified worker exposures to lead

and arsenic exceeding Occupational Safety and

Health Administration (OSHA) permissible

exposure limits (PELs), the Shot House has been

designated a regulated area as described in the

OSHA comprehensive standards for lead (29 CFR

1910.1025) and arsenic (29 CFR 1910.1018).

Because only new mild steel coated with waterbased, “lead-free” primers undergo abrasive blasting

in this facility, the presence of lead and arsenic was

an unexpected finding and the source had not been

determined. Analysis of welding fume during the

process step prior to abrasive blasting (Factory

Assembly) by Avondale did not identify the presence

of lead or arsenic. Personnel assigned to, or who

may have a need to work in this facility, participate

in the lead and arsenic program. This program

includes exposure assessment (air sampling,

biological monitoring), training, personal protective

equipment (PPE), etc. A decontamination trailer

(lockers, showers, “clean” and “dirty” side) has been

installed adjacent to the Shot House, and each

worker is provided two sets of clothing per day.

Work clothing is laundered by a contractor.

METHODS

General

Upon receipt of the HHE request, additional

information regarding the reported health problems

and suspect environmental contaminants was

obtained from the requestor. Specific areas of

concern identified by the HHE requestor were the

Factory and the abrasive blasting operation.

Discussions were held with Avondale safety and

health personnel to obtain process and job

descriptions for operations in these areas. During

these discussions, Avondale representatives

indicated that additional ventilation controls and

evaluation techniques were being considered for

certain activities involving the lead program.

Initial Site Visit

On August 27, 1997, NIOSH conducted an initial

site visit at the Avondale Shipyards facility. The

purposes of this site visit were to identify areas

where a NIOSH evaluation would be productive and

to define the scope of any future activities. To

accomplish this objective, efforts were focused on

the following:
Health Hazard Evaluation Report No. 97-0260-2716 Page 3

C Company lead and arsenic program (medical

surveillance, environmental monitoring,

controls)

C (OSHA) Log and Summary of Occupational

Injuries and Illnesses (Form 200) for 1997

C Activities involving welding/torch cutting in the

Factory

C Abrasive blasting activities and procedures

During this site visit, a walkthrough inspection was

conducted of the Factory, the Shot House, and the

decontamination facilities for personnel in the lead

and arsenic program. Avondale representatives

provided an overview of the shipyard industrial

hygiene and safety program and a copy of a report

from a recent (March 1995) comprehensive safety

and health program evaluation prepared by the

OSHA Director of Maritime Standards. 

Follow-up Site Visit

On October 21-23, 1997, NIOSH investigators

conducted a follow-up site visit at the Avondale

facility. During this site visit, personal breathing

zone (PBZ) air samples were collected to evaluate

worker exposure to welding fume in the factory and

contaminants generated during abrasive blasting

operations in the Shot House. A detailed review of

welding activities was conducted to better

understand the welding tasks in the factory and to

allow NIOSH to offer specific ventilation or work

practice controls recommendations. PPE practices

were also reviewed during this survey. Bulk samples

of both new and used abrasive blasting grit were

obtained for metal analysis. The biologic

monitoring results for employees participating in

Avondale’s lead and arsenic exposure programs for

the period 1995 to the present were reviewed. Along

with the biologic monitoring data, Avondale also

provided environmental sampling results for arsenic

and lead performed in the Shot House. 

Welding Fume

Full-shift welding fume exposures were measured on

five welders during the first shift (7:00 a.m. - 3:30

p.m.) on October 22. To prevent overloading,

sample filter cassettes were replaced with new ones

during the lunch period. The morning sampling

period ran from 7:00 a.m. - 12:00 p.m., and the

afternoon sampling period was from 12:30 p.m. -

3:30 p.m.. Two of the welders sampled worked on

the same unit in the Unit Department, one welder

worked along Platen 20 in the CPSU Department,

and one welder worked along Platen 40. A fifth

welder was sampled for part of the afternoon while

he worked in a confined space (Inner Bottom) inside

one of the units. 

Abrasive Blasting

PBZ air samples were collected from 11 abrasive

blasters during the second shift on October 22 and 23

in the Shot House. For each abrasive blaster

monitored, air samples were collected both inside

and outside the abrasive blasting hood. Additionally,

each abrasive blaster wore a “passive” monitor to

determine the extent of rebound, or inertia-driven,

shot that entered the sampling cassette. The sample

collected outside the abrasive blaster’s hood, and the

passive sample, were further analyzed by removing

the larger size particulate fraction (loose bulk) from

the filter cassette and analyzing this portion

separately. This monitoring strategy was employed

to help determine the extent to which large (believed

to be non-inhalable) particles of blasting materials

affect the sampling results.

All PBZ samples (both welding and abrasive

blasting) were analyzed gravimetrically to determine

the total particulate concentration, and chemically, to

determine the concentration of the following metals:

lead, arsenic, iron, manganese, copper, and

chromium. 
Page 4 Health Hazard Evaluation Report No. 97-0260-2716

Bulk Samples

Eight bulk samples of new and recycled shot were

collected in duplicate from the Shot House for metal

analysis to help determine the source of lead and

arsenic previously detected in air samples collected

by Avondale. Steel grit samples were collected from

both grit pots (north and south side) servicing the

Shot House, from the coarse and fine reject

collectors, and from inside the Shot House floor. All

air samples were placed on hold until the bulk

sampling results became available, to ensure that

appropriate elemental analysis was conducted.

The analytical methodology used for the air and bulk

samples is described in Appendix A.

EVALUATION CRITERIA

As a guide to the evaluation of the hazards posed by

workplace exposures, NIOSH field staff employ

environmental evaluation criteria for the assessment

of a number of chemical and physical agents. These

criteria are intended to suggest levels of exposure to

which most workers may be exposed up to 10 hours

per day, 40 hours per week for a working lifetime

without experiencing adverse health effects. It is,

however, important to note that not all workers will

be protected from adverse health effects even though

their exposures are maintained below these levels. A

small percentage may experience adverse health

effects because of individual susceptibility, a

pre-existing medical condition, and/or a

hypersensitivity (allergy). In addition, some

hazardous substances may act in combination with

other workplace exposures, the general environment,

or with medications or personal habits of the worker

to produce health effects even if the occupational

exposures are controlled at the level set by the

criterion. These combined effects are often not

considered in the evaluation criteria. Also, some

substances are absorbed by direct contact with the

skin and mucous membranes, and thus potentially

increase the overall exposure. Finally, evaluation

criteria may change over the years as new

information on the toxic effects of an agent become

available.

The primary sources of environmental evaluation

criteria for the workplace are: (1) NIOSH

Recommended Exposure Limits (RELs)1

, (2) the

American Conference of Governmental Industrial

Hygienists' (ACGIH®) Threshold Limit Values

(TLVs®)2

, and (3) the U.S. Department of Labor,

OSHA PELs3

. In July 1992, the 11th Circuit Court

of Appeals vacated the 1989 OSHA PEL Air

Contaminants Standard. OSHA is currently

enforcing the 1971 standards which are listed as

transitional values in the current Code of Federal

Regulations; however, some states operating their

own OSHA-approved job safety and health

programs continue to enforce the 1989 limits.

NIOSH encourages employers to follow the 1989

OSHA limits, the NIOSH RELs, the ACGIH TLVs,

or whichever are the more protective criterion. The

OSHA PELs reflect the feasibility of controlling

exposures in various industries where the agents are

used, whereas NIOSH RELs are based primarily on

concerns relating to the prevention of occupational

disease. It should be noted when reviewing this

report that employers are legally required to meet

those levels specified by an OSHA standard and that

the OSHA PELs included in this report reflect the

1971 values.

A time-weighted average (TWA) exposure refers to

the average airborne concentration of a substance

during a normal 8- to 10-hour workday. Some

substances have recommended short-term exposure

limits (STEL) or ceiling values which are intended to

supplement the TWA where there are recognized

toxic effects from higher exposures over the

short-term.

Welding Hazards

The effect of welding fumes on an individual’s

health can vary depending on such factors as the

length and intensity of the exposure and the specific

metals involved. The content of welding fumes

depends on the base metal being welded, the welding

process and parameters (such as voltage and
Health Hazard Evaluation Report No. 97-0260-2716 Page 5

amperage), the composition of the consumable

welding electrode or wire, the shielding gas, and any

surface coatings or contaminants on the base metal.

It has been suggested that as much as 95% of the

welding fume actually originates from the melting of

the electrode or wire.4

 The flux coating (or core) of

the electrode/wire may contain up to 30 organic and

inorganic compounds. The primary purpose of the

flux is to release a shielding gas to insulate the weld

puddle from air, thereby protecting against

oxidation.5

 The size of welding fume particulate is

highly variable and ranges in diameter from less than

1-micrometer (:m) (not visible) to 50-:m (seen as

smoke).6

 

In general, welding fume constituents may include

minerals, such as silica and fluorides, and metals,

such as arsenic, beryllium, cadmium, chromium,

cobalt, nickel, copper, iron, lead, magnesium,

manganese, molybdenum, tin, vanadium, and

zinc.6,7,8 Low-carbon steel, or mild steel, is

distinguished from other steels by a carbon content

of less than 0.30%. This type of steel consists

mainly of iron, carbon, and manganese, but may also

contain phosphorus, sulphur, and silicon. Most toxic

metals, such as nickel and chromium which are

present in stainless steel, are not present in low

carbon steel.

A PEL for total welding fumes has not been

established by OSHA; however, PELs have been set

for individual welding fume constituents (e.g., iron,

manganese), and the PEL for total particulates not

otherwise regulated is 15 milligrams per cubic meter

(mg/m3

) as an 8-hour TWA.9 The ACGIH has

established a TLV of 5 mg/m3

 TWA for welding

fumes. The ACGIH suggests that “conclusions

based on total fume concentration are generally

adequate if no toxic elements are present in the

welding rod, metal, or metal coating and if

conditions are not conducive to the formation of

toxic gases.”2 The ACGIH also recommends that arc

welding fumes be tested frequently to determine

whether exposure levels are exceeded for individual

constituents.2

 NIOSH has concluded that it is not

possible to establish an exposure limit for total

welding emissions since the composition of welding

fumes and gases vary greatly, and the welding

constituents may interact to produce adverse health

effects. Therefore, NIOSH recommends controlling

total welding fume to the lowest feasible

concentration (LFC) and meeting the exposure limit

for each welding fume constituent.10 The potential

health effects and NIOSH RELs for the metals

measured in the environmental samples during this

survey are shown in the following table. Evaluation

criteria for lead and arsenic are presented separately.

Element NIOSH REL

(mg/m3

)

Principle Health Effects11

Chromium 0.5* skin and mucous membrane

irritation, possible lung cancer

Iron 5 benign pneumoconiosis

(siderosis)

Manganese 1 TWA

3 STEL

central nervous system effects,

pneumonitis, headaches

Copper 0.1 (fume)

1 (dust/mist)

upper respiratory irritation,

metal fume fever

* = Chromium can occur in various oxidation states. Certain hexavalent

chromium compounds (chromic acid and chromates) have been shown to

be carcinogenic. NIOSH recommends controlling exposure to the LFC for

these compounds. Hexavalent chromium compounds have been detected

in stainless steel welding processes.7

In addition to welding particulate (known as fume),

many other potential health hazards exist for

welders. Welding operations can produce gaseous

emissions such as ozone, carbon monoxide, nitrogen

dioxide, and phosgene (formed from chlorinated

solvent decomposition).6,7,8 Welders can also be

exposed to hazardous levels of ultraviolet light from

the welding arc if welding screens or other

precautions are not used. Ergonomic problems are

also a consideration due to various contorted

positions welders assume for some welding tasks. 

A detailed review of control options for reducing

exposure to welding fume is provided in

Appendix B.

Abrasive Blasting

Abrasive blasting entails using pneumatic or

hydraulic pressure or centrifugal force to direct a
Page 6 Health Hazard Evaluation Report No. 97-0260-2716

blast of abrasive material (wet or dry) against a

surface to clean, remove burrs, or develop a surface

finish. Abrasive blasting is used in a variety of

industries, and there are a wide variety of blasting

techniques, involving both handheld or automatic

equipment.12 A large number of metallic and nonmetallic abrasives are commonly used. Because

large quantities of dust are generated, abrasive

blasting is usually conducted in exhausted

enclosures, often equipped with air pollution control

devices and abrasive recycling systems. In the

United States, the use of sand containing high

concentrations of free silica as an abrasive blasting

agent continues to present a major hazard to

workers.12,13 Workers conducting abrasive blasting

are exposed to both safety (rebound shot, high

pressure, etc.) and health (high levels of dust from

abrasives and material being blasted) hazards, and a

number of precautions are necessary to ensure

adequate protection. OSHA has established

regulatory requirements for ventilation, enclosures,

and PPE during abrasive blasting. Airline

respirators specifically designed for abrasive

blasting (Type “CE” supplied-air) are required for

work inside of blast-cleaning rooms. These

respirators are of rugged construction and equipped

with coverings to provide head, neck and upper body

protection from rebounding abrasive blasting

material.14

Assessing exposure during abrasive blasting for

compliance purposes requires collecting the sample

outside the abrasive blast hood. These efforts to

monitor worker exposure during abrasive blasting

within enclosures often result in measuring

concentrations far exceeding recommended limits.15

This is because of the high dust concentrations

generated in an abrasive blasting environment and

the potential for rebound shot to affect the sampling

results. The larger rebound shot enters the sampling

cassette and, even though it is not “inhalable,”

contributes, disproportionately, to the measured PBZ

exposure.

Arsenic

Arsenic is a naturally occurring element which can

form a variety of inorganic and organic compounds,

which have different toxicities. Various arsenic

compounds are also found in some foods (e.g.,

certain marine species may contain very high

concentrations of non-toxic organic arsenic).11,16,17

Most (68%) industrial use for arsenic is for

pesticides (wood preservatives primarily). Other

uses include agricultural chemicals (23%), glass

(4%) and non-ferrous alloy (3%) manufacturing.19

Arsenic is found in most fossil fuels and in cigarette

smoke. The natural arsenic content of soil varies

between 0.1 and 80 parts per million, (ppm).17 In

general, soluble inorganic arsenic compounds

(arsenic combined with oxygen, chlorine, or sulfur)

are considered to be the principal toxic species.

Conversely, most organic arsenic compounds have

relatively low toxicity.17,18

Inorganic arsenic compounds may cause adverse

health effects following exposure via inhalation,

ingestion, or dermal contact. Acute exposure to

inorganic arsenic can cause nausea, vomiting,

diarrhea, weakness, loss of appetite, cough, and

headache. Chronic exposure can result in weakness,

nausea, vomiting, skin and eye irritation,

hyperpigmentation, dermatitis, and numbness and

weakness in the legs and feet.11 Peripheral vascular

disease ("Blackfoot disease") has been reported to

occur in association with chronic arsenic exposure

from contaminated drinking water and among wine

makers exposed to arsenical pesticides.17

There is clear evidence that chronic oral exposure to

elevated levels of arsenic increases the risk of skin

cancer. Inhalation of certain arsenic compounds can

also result in lung cancer.17,18 NIOSH considers

arsenic a potential occupational carcinogen,

recommends controlling occupational exposures to

the lowest feasible concentration, and has established

an REL of 2 micrograms per cubic meter (μg/m3

) as

a 15-minute ceiling limit.1
Health Hazard Evaluation Report No. 97-0260-2716 Page 7

The OSHA arsenic standard (29 CFR 1910.1018)

requires a medical surveillance program for workers

exposed to arsenic in the workplace. In 1996, OSHA

issued a memorandum stating that sputum cytology

(part of the OSHA medical surveillance program) is

not appropriate in the surveillance of arsenic-exposed

workers and that worksites not performing sputum

cytology would not be issued citations

(Memorandum from OSHA Directorate of

Compliance Programs, August 1996).

Determination of urinary arsenic is not included in

the standard, although biologic monitoring for

arsenic is available as a means of assessing exposure

to arsenic compounds. Analysis for total arsenic

may be heavily influenced by organic arsenic

compounds found in seafood.11 Biologic monitoring

for occupational exposure to arsenic is best

conducted by analyzing inorganic arsenic and its

metabolites, monomethylarsonic acid and cacodylic

acid, as these compounds represent only inorganic

arsenic exposure.

Detection of arsenic in urine is an indication of a

recent exposure only (within a few days); arsenic is

rapidly excreted in urine and has a biological halflife of only one or two days. Normal values of total

arsenic in urine vary from 13 to 46 :g/L.19 The

ACGIH biological exposure index (BEI) for

occupational exposure to arsenic (including

inorganic arsenic and methylated metabolites) is

50 micrograms per gram creatinine (ug/g creat) in

urine samples taken at the end of a workweek.2

Lead

Lead is a bluish-gray heavy metal with no

characteristic taste or smell and is ubiquitous in U.S.

urban environments due to the widespread use of

lead compounds in industry, gasoline, and paints

during the past century. Absorbed lead accumulates

in the body in the soft tissues and bones. Lead is

stored in bones for decades, and may cause health

effects long after exposure as it is slowly released in

the body. 

Lead can enter the body by inhalation or ingestion

and can adversely affect numerous body systems.

Skin absorption does not occur except for certain

organo-lead compounds such as tetraethyl lead.

Although lead is a naturally occurring element, most

exposures to lead occur from human activities.20

Inhalation is considered to be the most important

occupational exposure route. Lead is a systemic

poison that serves no useful function after absorption

in the body, the health consequences of which can

occur after periods of exposure as short as days or as

long as several years.21 Once absorbed, lead is

excreted from the body very slowly. Absorbed lead

can damage the kidneys, peripheral and central

nervous systems, and the blood forming organs

(bone marrow).11 These effects may be felt as

weakness, tiredness, irritability, digestive

disturbances, high blood pressure, kidney damage,

mental deficiency, or slowed reaction times.

Damage to the central nervous system in general,

and the brain (encephalopathy) in particular, is one

of the most severe forms of lead poisoning.11,21

Chronic lead exposure is associated with infertility

and with fetal damage in pregnant women.11

Although the hazards of lead have been known for

some time, occupational exposure to lead is still a

significant problem in some industries (battery

reclamation, radiator repair, construction). In 1990,

the U.S. Public Health Service established a national

goal to eliminate worker exposures resulting in

blood lead (PbB) concentrations greater than

25 micrograms per deciliter (:g/dl).22

Avondale is governed by the OSHA Maritime Lead

Standard (CFR 1915.1025), which is identical to the

General Industry Lead Standard (CFR 1910.1025).

The standard establishes a PEL for airborne lead of

50 :g/m3

, and an action level of 30 :g/m3.

23,21 The

portion of the lead standard dealing with biologic

monitoring calls for employees exposed above the

action level to have available to them measurement

of PbB and zinc protoporphyrin (ZPP) every six

months after initial testing is done. PbB levels

greater than 40 micrograms (μg) per 100 grams

(μg/100g [1 μg/100g = 1 μg/dl]) call for increased

testing frequency, and PbB levels above 50 ug/100g

call for removal from exposure until the PbB level
Page 8 Health Hazard Evaluation Report No. 97-0260-2716

falls below 40 μg/100g. The measurement of ZPP in

the blood is used in monitoring employees as a

measure of longer-term biologic effect of lead

exposure.11,2 Measurements of ZPP of greater than 50

μg/dl have been used as an indication of excess lead

exposure.11,24 However, the ZPP test is felt to be an

insensitive and non-specific test for lower-level

occupational exposure.2

A review of the correlation of airborne lead levels

and PbB levels suggests there is no good way to

correlate airborne lead exposures with subsequent

PbB levels.25

RESULTS

Industrial Hygiene

According to Avondale representatives, silica has not

been used as an abrasive blasting agent since 1972,

and there is currently no fiberglass work at the

shipyard. All fiberglass work (including the use of

related chemicals acetone and styrene) was

completed in May 1997, when the last of four Navy

Minehunter vessels was refurbished. 

Factory

Workplace Observations

All welding observed was on carbon steel;

approximately 65% of the welding operations in the

Factory, and 90% of the work in the Unit

Department, were flux cored arc welding (FCAW).

During FCAW, a consumable wire (0.052" diameter

Dualshield T-1 & T-2 Flux Core, ESAB Group,

Inc.) is continuously fed through a welding gun. The

wire is hollow and filled with a flux core composed

of various metals or minerals that promote the weld

process by removing impurities and preventing

oxidation. Shielding gas (carbon dioxide) is

supplied at the gun tip to prevent oxidation of the

base metal during the FCAW process. 

The remainder of the welders in the Factory

primarily use the shielded metal arc welding

(SMAW or “stick welding”) process. For example,

tacking of the tie-downs (or cloverleafs) onto grids in

the Unit Department was done with SMAW. The

SMAW technique requires the use of a hand held,

flux-coated consumable electrode of a finite length to

produce an arc. No shield gas is used with this

process.

The ventilation system in the Factory consists of

ridge vents which provide passive general ventilation

(no mechanical general dilution ventilation has been

installed). Portable blowers are used in the Unit

Department to provide large quantities of air during

some confined space welding operations. The

portable ventilation units observed during this site

visit consisted of collapsible duct with a blower,

usually mounted on the top of the unit, that forces air

into the confined area where welding is occurring.

Welders wear half-mask air purifying respirators

(APR) with either high efficiency air purifying

(HEPA) filters or combination organic vapor

cartridges with a particulate filter, when working in

open areas. According to Avondale representatives,

welders are provided with supplied air respirators

when conducting certain tasks (Arc Gouging) in

confined areas, or when there is no forced air

ventilation for confined area work. No workers

wearing supplied air respirators were observed.

Welders also utilized welding hoods and protective

gloves. Some welding tasks require workers to stay

in a fixed location for the majority of the work shift.

Other welding tasks (e.g., tack welding tie-downs)

required the workers to frequently move to different

locations. No welding screens or shielding to

prevent or reduce exposure to welding flash were in

use in the Factory

An automated welding process (“tripod welder”),

which was installed as an ergonomic control

measure, was observed. The electrode was

positioned over the area to be welded, at an angle,

situated in a tripod holder. This was a semiautomatic device; as the electrode melted, gravity

pulled the electrode down and the weld traveled

along the work piece. After the electrode was

consumed it was manually replaced with another
Health Hazard Evaluation Report No. 97-0260-2716 Page 9

electrode and the tripod welder was moved further

down the piece.

Air Sampling Results

The results of the air samples collected from welders

in the Factory are shown in Table 1. The highest

measured total particulate weld fume sample

(55 mg/m3

) was from a worker welding in a confined

area (inside an Inner Bottom Unit) for approximately

1.5 hours. Forced air ventilation was provided

during this work from a blower and collapsible duct

system. This worker wore a half-mask APR with a

HEPA filter while welding. The other four welding

fume samples were collected over the majority of the

work shift (approximately 400 minutes), and the total

particulate weld fume results ranged from

3.15 mg/m3

 to 19.1 mg/m3. Iron was the highest

measured metal. The highest iron concentration

detected (12.5 mg/m3

) was in the sample from the

welder in the confined area. Exposures measured on

the other four welders ranged from 0.98 mg/m3

 to

6.1 mg/m3

. The NIOSH REL for iron oxide fume is

5 mg/m3

. Measured lead concentrations ranged from

0.003 mg/m3

 to 0.010 mg/m3 and were all below

both the NIOSH REL (0.1 mg/m3

) and OSHA PEL

(0.05 mg/m3

). Arsenic was not detected in any of the

samples collected.

Shot House

All workers evaluated wore supplied-air abrasive

blasting respirators (Bullard 88 Type “CE”)

equipped with a vortex tube for cooling. These

workers also wore half-mask APR’s equipped with

HEPA filters as additional protection. Although the

APR’s were not an integral part of the blast hood, the

workers monitored indicated that use of the

additional respirator was a common practice during

abrasive blasting. Avondale representatives

indicated the supplied air system is designed to

provide clean air at a delivery rate within a range of

6 cubic feet per minute (cfm) to 15 cfm. These

workers also indicated the vortex tube provided

considerable cooling during use and significantly

reduced heat exposure.

Abrasive blasting only occurs during the second

(night shift) at Avondale. A review of the

decontamination trailer found the design to be sound.

The trailer was equipped with a “dirty” and “clean”

side, showers and lockers. Clean work clothes (two

sets per day) are furnished by Avondale for

employees who work in the Shot House. The

decontamination trailer has a dedicated lunchroom

area for workers; Avondale Safety and Health

representatives indicated that periodic wipe sampling

for lead is conducted to verify the area is free from

contamination. 

Air Sampling Results

Eleven abrasive blasters were monitored in the Shot

House on successive days (October 22-23, 1998).

The results of the air sampling conducted in the Shot

House are shown in Tables 2 (gravimetric) and

3 (elemental). As previously described, three sample

sets (inside the hood, outside the hood, “passive”)

were collected from each abrasive blaster, and on

two of the sample sets (outside the hood, passive),

that portion of the sample that was loose bulk (large

grit) was separated and analyzed separately. All air

samples collected outside the abrasive blast hood

greatly exceeded the OSHA PEL and ACGIH TLV

for total particulate and the NIOSH REL for iron for

both the “small particle”*

 (OH-A) and “large

particle” (OH-B) fraction. The small particle

gravimetric air sample results ranged from

34.6 mg/m3

 (AB #6) to 64.1 mg/m3 (AB #11). The

large particle component concentrations ranged from

250.3 mg/m3

 (AB #8) to 5860.7 mg/m3 (AB #9).

Corresponding ranges of iron measured in the small

particle portion of the sample were 15.2 mg/m3

 (AB

#6) to 29.2 mg/m3

 (AB #5, #11), and 172.3 mg/m3

* For purposes of discussion, the “small particle” fraction

of the sample is that portion remaining on the filter after

removal of large loose grit from the filter cassette prior to

analysis. A more robust definition is not available as a

specific size range (e.g. minimum and maximum particle

diameter) for the “small particle” fraction was not

determined, but was subjectively determined by the analyst.

The component of the sample removed (“large particle”)was

primarily rebound shot and considered too large to pose an

inhalation hazard. 
Page 10 Health Hazard Evaluation Report No. 97-0260-2716

Abrasive Blast Air Sam pling Results: 

Lead: Sm all Particle Fraction vs Large 

Particle Fraction

0

5 0

100

150

200

250

300

350

1 2 3 4 5 6 7 8 9 10 11

Abrasive Blaster #

ug/m3

Small Particle

Large Particle

 Figure 1-Outside the Blast Hood Lead Results

Contribution of the Small Particle Fraction to the Total 

Particulate Concentration in Milligrams per Cubic Meter

Abrasive Blast Sampling: Outside the Blast Hood Samples

Small Particle

Large Particle

Figure 2

(AB #8) to 1926 mg/m3

 (AB #9). The NIOSH REL

for iron oxide dust (as iron) is 5 mg/m3

.

The lead concentrations measured in the “outside the

hood” samples ranged from 1 microgram per cubic

meter (μg/m3

) to 10 μg/m3 for the small particle

component and 8 μg/m3

 to 260 μg/m3 for the large

particle portion (Figure 1). Four of the 11 arsenic

samples collected outside the hood exceeded the

NIOSH REL of 2 μg/m3

. These samples (large

particle fraction) ranged from 30 μg/m3

 to 50 μg/m3.

Several samples were between the analytical limit of

detection (LOD) and the limit of quantification

(LOQ), or had an LOD exceeding the NIOSH REL.

The small particle component of one outside the

hood arsenic sample (AB #11) showed a

concentration (8 μg/m3

) that exceeded the NIOSH

REL. 

For the other elements measured in the “outside the

hood” samples, manganese exceeded the NIOSH

REL of 1.0 mg/m3

 on the large particle component of

all samples, but not on any small particle fractions.

For both copper (NIOSH REL = 1.0 mg/m3

) and

chromium (NIOSH REL = 0.5 mg/m3

), the large

particle portion of the sample exceeded the REL on

3/11 samples, but on none of the small particle

portions.

The outside the hood sample results show that the

large particle steel grit component of the air sample

is the primary contributor to the reported total

concentrations. That portion of the air sample

considered to represent the small particle fraction

entailed an average of only 3.5 % of the total

gravimetric sampling results (Figure 2).

The “passive” samples collected outside the workers

abrasive blast hood contained a highly variable but

significant amount of inertia-driven (rebound) grit

(Figure 3). The mass of grit detected on the

“passive” samples ranged from 1.58 mg to 366.5 mg.

If these weights were detected on a filter connected

to an air sampling pump with an average flow rate of

2 l/m for 400 min (800 l volume), the range of

concentrations would have been 2 mg/m3

 to

458 mg/m3

. This finding further substantiates the

contention that there is a significant contribution of
Health Hazard Evaluation Report No. 97-0260-2716 Page 11

Abrasive Blast Air Sam pling: 

M illigram s M easured: Active vs. 

Passive Sam ples

0

500

1000

1500

2000

2500

1 2 3 4 5 6 7 8 9 10 11

Abrasive Blaster #

Milligrams Measured

Passive MG OH-M G

 Figure 3-Outside the Blast Hood (OH-MG) versus

 Passive Air Samples (Passive MG)

large particle aerosol when assessing exposure to

abrasive blasting and collecting the sample outside

the abrasive blast hood. 

All of the inside the hood air samples except arsenic

were below applicable NIOSH RELs. For some of

the inside the hood air samples, the analytical LOD

for arsenic exceeded the NIOSH REL, thus

adherence to the REL could not be demonstrated.

One sample (AB #6) showed an arsenic

concentration that was between the LOD and LOQ.

Several of the metals measured were below the

analytical LOD. These results indicate the abrasive

blast hoods were being worn properly and were

providing sufficient protection.

Respirator Efficacy

Because data was collected from both inside and

outside the supplied air respirator worn by the

abrasive blasters, the efficacy of the respiratory

protection was assessed for each worker. In general,

the protection that a given respirator will provide is

determined by multiplying the exposure limit for the

contaminant by the assigned protection factor (APF)

for that specific class of respirators.26 The APF is

considered the minimum anticipated level of

protection a properly functioning respirator, or class

of respirators, will provide to a percentage of

properly trained and fitted users.26 The actual

performance of a correctly worn respirator under

workplace conditions is determined by calculating

the workplace protection factor (WPF). The WPF is

defined as the ratio of the estimated contaminant

concentration outside the respirator to the

contaminant concentration inside the respirator

(when TWA samples are collected simultaneously

while the respirator is properly worn during normal

work activities).26 During this survey, WPF’s were

calculated using the combined (small and large

particle fraction) concentration for each contaminant

measured to determine the effect of contaminant

selection on the WPF (Figure 4). The lowest

calculated WPF using the combined measured

concentrations showed a respirator protection factor

of 2817. WPF’s for several of the workers

monitored were in excess of 10,000. WPFs were

also determined using that portion of the air sample

considered to represent the small particle fraction.

Using the smaller size particle concentration, the

calculated WPFs were much lower, and ranged from

183 to 1282 for the gravimetric measurements, and

210 to 3700 for specific metal concentrations.

Because some of the measured contaminants were

not detected in the inside the hood air samples, no

WPFs’ were calculated for these components.
Page 12 Health Hazard Evaluation Report No. 97-0260-2716

W orkplace Protection Factor by 

Contaminant Measured

0

2000

4000

6000

8000

1 0000

1 2000

1 2 3 4 5 6 7 8 9 10 11

Abrasive Blaster #

Workplace Protection Factor

Gravim etric

Manganese

Iron

Copper

Figure 4 - Workplace Protection Factors Determined

by Contaminant Measured Using the Combined (small

and large particle) Concentration

Bulk Sampling Results

The results of the bulk samples are reported in Table

4. The steel grit utilized for the blasting (Metgrain

G-40, Chesapeake Specialty Products) has a size

range of 0.0394 to 1.0 millimeter (mm) (all pass

through a #18 screen). The reject system is designed

to discard all particles smaller than approximately

212 μm (pass through a #65 mesh screen). No

cadmium was detected in any of the bulk samples;

thus, no air samples were analyzed for this metal.

The bulk samples showed elemental concentrations

of lead in the range of 4.3 μg/g (or part per million)

in the virgin shot to 223.4 μg/g in the fine reject

sample, and arsenic in the range of 16.1 μg/g (fine

reject) to 74.1 μg/g (recycle grit). Analysis did not

indicate that high iron concentrations interfere with

detecting low levels of lead or arsenic using

inductively coupled plasma emission spectroscopy

(ICAP) as described in NIOSH Manual of Analytical

Methods, 4th edition, method #7300. There was

some variation in results between the two

laboratories as shown in the table.

Initial analysis of the bulk sample of steel plate

(Steel Grade AH 36, U.S. Steel Group) from the

Factory indicated a substantial lead contact (16,829

ug/gm). However, analysis of a second sample and

re-analysis of the first steel plate sample did not

confirm this initial finding and only low levels of

lead were detected (10.8 ug/gm, 18 ug/gm,

respectively). Analysis of the 2-part epoxy resin

(Amercoat 3207 Cure and Resin) used as a preconstruction primer in the Factory found a low level

of lead (2.9 ug/gm) in the resin, and less than

detectable (<0.42 ug/gm) in the cure.

Medical

Records Review

Employees from welding-unit construction and

shipfitting-unit construction in the Factory had

71 entries in the OSHA 200 log for the first eight

months of 1997. Welding-flash burns made up

42 (59%) of the entries, with some of the other

entries consisting of chemical irritation (13 [18%]),

heat stress (6 [8%]), musculoskeletal problems

(3 [4%]), and chemical inhalation (3 [4%]).

Employees from the paint department and paint-unit

construction who conduct painting and/or abrasive

blasting in the Shot House had 33 entries in the

OSHA 200 log, with 18 (55%) involving chemical

irritation, 6 (18%) involving abrasion, 5 (15%)

involving contusion, and the remainder made up of

1 each of “lung disease,” pleural plaques, rash, and

“sand in face.”

Lead Program

At the time of the NIOSH site visit, there were

approximately 70 Avondale employees participating

in the lead program. The number of participants in

the program was reported to vary depending on the

types of work in the shipyard at any given time;

employees potentially exposed to lead above the
Health Hazard Evaluation Report No. 97-0260-2716 Page 13

action level, as identified by the industrial hygiene

department, are enrolled in the lead surveillance

program. For example, during a recent refurbishing

job (American Heavy Lift) involving work with leadcontaining material, 235 workers were entered into

the program. Some employees, such as employees in

the repair department and the Shot House, are

maintained in the lead program continuously. 

Avondale lead air sampling results included

347 measurements of airborne lead among

73 different employees involved in abrasive blasting.

The mean air lead concentration was 32.0 ug/m3

(median - 4.3 ug/m3; range - 0 to 1,071 ug/m3). The

biologic monitoring data included 234 measurements

of PbB and ZPP among 67 different employees

involved in the abrasive blasting operation. The

mean PbB level was 4.4 ug/dl (median - 4.0 ug/dl;

range - 0 to 18 ug/dl). The mean ZPP level was 41.4

ug/dl (median - 40.0 ug/dl; range - 22 to 72 ug/dl).

Avondale reported that the PbB and ZPP

determinations were performed by an OSHAapproved contract laboratory.

Arsenic

Avondale reported that all employees working in the

Shot House were enrolled in the arsenic exposure

surveillance program. The data from this program

included measurements of total urine arsenic in

employees involved in the abrasive blasting

operation from January 1995 through October 1997.

Ninety measurements were made among 54 different

employees. The mean urine arsenic level for all tests

was 41.3 micrograms per liter (ug/l) (median -

30 ug/l; range - 0 to 180.3 ug/l). There were

22 samples with a total arsenic level above the

ACGIH BEI (which excludes organic arsenic of

marine origin) of 50 ug/g creatinine. Avondale

reported at the time of the review that elevated

arsenic levels were followed-up with additional

medical testing. As part of the arsenic surveillance

program, Avondale has been collecting sputum

samples as required by the original OSHA standard;

none were found to be positive for malignancy.

DISCUSSION

Welding activities in the Factory result in substantial

exposure to welding fume, and continued adherence

to the proper use of respiratory protection is

necessary until effective engineering or

administrative controls can be implemented. With

one exception, the use of respirators in the Factory

appeared to be adequately protecting workers. One

welder working in a confined area (Inner Bottom) for

approximately 100 minutes had a measured

exposure of 55 mg/m3

, despite the use of forced air

ventilation. This measured concentration and

observation of the work practices suggest a higher

degree (supplied air) of respiratory protection is

needed for this activity. A half-mask air purifying

respirator has an assigned protection factor of 10,

indicating that, if properly worn, the device would

provide protection in a contaminant concentration up

to 10 times the applicable limit. As the ACGIH TLV

for welding fume is 5 mg/m3

, the measured

concentration (albeit not a full-shift TWA

measurement) during confined area welding

exceeded this criterion by more than 10 times. No

other constituents of the weld plume (gases such as

carbon monoxide, fluorides, etc.) were measured

during this survey, but it is likely that these

contaminants are also generated during the welding

process. 

The limited medical component of this HHE does

not allow NIOSH investigators to draw conclusions

concerning the potential occupational exposures

which could account for the respiratory complaints

reported in the HHE request. Concentrations of air

contaminants (welding fume in the Factory, total

particulate and metals in the Shot House) higher than

those documented in our survey and/or improper use

of respiratory protection among exposed workers are

factors that could potentially contribute to respiratory

health effects among these workers. Welding flash

burns were the most commonly recorded injury in

the Factory, and there is a need to ensure that

appropriate shielding is used to reduce the potential

for exposure, of both workers and others in the area,

to the welding arc.
Page 14 Health Hazard Evaluation Report No. 97-0260-2716

Because of the size of the Factory and the mobility

of the welders, ensuring an effective ventilation

system to reduce welding fume exposures presents a

difficult and complex design issue. Avondale has

been considering providing general dilution

ventilation (GDV) or local exhaust ventilation

(LEV). While GDV may result in some reduction in

the visible haze and overall contaminant levels, it

would likely have little impact in reducing exposures

for welders. The benefit of LEV is efficiency by

contaminant capture at the point of generation. LEV,

alone or in conjunction with GDV, would provide

superior protection to the welder as compared to just

a general exhaust system for the facility.

Implementation of effective LEV systems as a

control option is complicated by the large number of

mobile welders in the Factory. Additional

information on ventilation as a welding fume control

is provided in Appendix B.

Although measured exposures outside the abrasive

blast hoods on all workers in the Shot House

exceeded NIOSH RELs, all but one of the samples

collected inside the workers’ blast hoods indicate

that these devices are being used properly and are

sufficiently protective. One sample for arsenic

showed an inside-the-hood concentration that was

between the analytical LOD and LOQ. Additional

protection is afforded by the work practice of

wearing a half-mask APR with HEPA filter to

augment the blast hood. All PbB levels were

< 20 ug/dl. The company’s biological monitoring

and air sampling data, as well as the NIOSH air

sampling data, indicate that the Shot House safety

and health program is effective in protecting against

overexposure to lead. 

The source of the lead detected in the Shot House

does not appear to be materials from the Factory.

The airborne lead is likely due to the small amounts

present in the steel grit. From the limited number of

samples collected, it appears that the lead content of

the small fine component of the abrasive grit is

higher than in the new, or larger-size, grit. One

possible explanation for this finding is that during

use, finer lead dust particles are continuously

generated from the fracturing of grit during blasting,

and then recirculated through the system, resulting in

a build-up of lead in the recycle stream.

PBZ arsenic concentrations outside the blast hood

exceeded the NIOSH REL of 2 μg/m3

, indicating

that the potential for arsenic exposure does exist

during blasting operations in the Shot House. As

with lead, the arsenic appears to come from the steel

grit, and the levels vary with the type of grit. The

total urinary arsenic concentrations, determined as

part of the medical surveillance program for arsenic,

cannot be effectively used to monitor occupational

exposure unless seafood has not been consumed for

2-3 days prior to the testing. Preferably, the urine

should be analyzed specifically for inorganic arsenic

and its metabolites.27 

Current sampling and analytical methodology for

evaluating exposure during abrasive blasting entail

collecting a particulate air sample outside the

abrasive blast hood. Air samples collected during

this HHE support the contention that these methods

do not accurately represent worker exposure to

inhalable lead and other elements during abrasive

blasting in confined spaces. This is because large

abrasive blasting grit particles enter the sampling

cassette inlet from inertia (high velocity rebound)

rather than through the action of the sampling pump,

where an airborne contaminant is collected in an air

sample of known volume. In the absence of

guidelines for the analysis of samples containing

large, non-inhalable particles, all dust and grit on the

sample filter is digested, analyzed, and the total

amount of the selected airborne contaminant (e.g.,

lead), is reported. Including these large, noninhalable particles in the analysis may thus

overestimate the concentration of inhalable lead (or

other metals).

This evaluation is consistent with a previous NIOSH

evaluation of a shipyard abrasive blasting operation

that found abrasive blaster exposures to lead in

excess of OSHA PELs despite the presence of only

low levels in the base metal, surface coatings, and

steel grit.28 Bulk samples collected during that study

found that the grit contributed the greatest amount of

lead and other metals. Standard sampling methods
Health Hazard Evaluation Report No. 97-0260-2716 Page 15

used to assess exposure resulted in large, noninhalable particles entering the monitoring cassette

due to high initial velocity. Even the relatively small

amount of lead in grit (approximately

100 micrograms per gram grit) resulted in a

significant contribution to the lead in the samples;

primarily from the random entrapment of large grit

particles in the filter cassettes. Other sampling

methods assessed in that study included placing the

sampling cassette behind the worker, use of a metal

shield to guard the cassette inlet, and the use of a

standard nylon cyclone. Sample placement and the

use of the shield did not reliably prevent large grit

particles from entering the cassette, and cyclones

were not useful because they frequently became

inverted as the blaster worked in confined areas.28

Even if they did perform effectively in this

environment, cyclones would not be an appropriate

measurement choice because they exclude all but the

respirable fraction. The investigators concluded that

conventional sampling and analytical techniques

result in an overestimation of worker exposures to

lead and other contaminants present in abrasive

blasting environments.

This issue is of considerable importance from a

regulatory standpoint, as administrative and

engineering controls prescribed by the OSHA lead

standard are triggered by full-shift personal lead

exposures in excess of the action level outside the

blasting hood. 

Determination of respirator efficiency by calculating

the WPF indicated that the abrasive blast hoods were

performing well. There was considerable variability

in the WPF depending on which contaminant was

selected for the calculation or when the small particle

fraction alone was used in the calculation. For some

of the measured contaminants, analytical variability

associated with the low concentrations detected may

have influenced these results. A previous study that

evaluated the performance of abrasive blast hoods

during the use of silica in a sand blasting booth found

an average WPF of 16,800 (geometric mean).29

CONCLUSIONS

Monitored exposures to welding fume components

exceeded applicable guidelines in the Factory.

However, except for one of the workers, the

respiratory protection worn by Factory welders was

sufficiently protective. Despite the use of forced air

ventilation during welding in confined areas, one

PBZ sample exceeded 50 mg/m3

, thus warranting a

higher level of respiratory protection than is

currently used for that activity until engineering or

work practice controls are implemented.

Observations of work practices in the Factory

suggest that the most likely choices for local exhaust

ventilation systems are movable hoods and fume

extraction guns.

Measured exposures to iron, manganese, and other

metals collected outside the workers abrasive blast

hood in the Shot House exceeded NIOSH RELs; all

measured exposures collected inside the abrasive

blast hood were below NIOSH RELs, or had a

reported limit of detection that was greater than the

REL. The source of lead and arsenic contamination

in the Shot House is likely the steel grit used as the

abrasive blasting agent. Significant levels of lead or

arsenic were not detected in the Factory. The safety

and health program in the Shot House, and the

controls in place ( PPE, administrative, engineering)

during abrasive blasting appear to be effectively

preventing worker exposure to lead and other

contaminants during abrasive blasting operations.

However, the biologic monitoring program for

arsenic currently uses measurement of urinary total

arsenic; these values cannot be interpreted without

taking into account dietary organic sources of

arsenic. Evaluation of the abrasive blast hood

performance found that there is a wide variability in

the calculated workplace protection factor depending

on the contaminant selected.

Current sampling and analytical methods do not

accurately represent employee exposure to lead or

other contaminants during abrasive blasting.

Measurement methods that more accurately estimate

the true exposure during abrasive blasting operations
Page 16 Health Hazard Evaluation Report No. 97-0260-2716

are needed. There are no methods currently

available to reliably collect a representative sample

outside the abrasive blast hood. As such, it appears

that collecting a sample inside the abrasive blast

hood is more representative of the workers’ exposure

and avoids the significant confounding factor of

large, non-inhalable materials. Air sampling results

obtained outside the abrasive blast hood may trigger

OSHA regulatory requirements for engineering

controls, respiratory protection, medical monitoring,

etc. Samples collected inside a properly selected and

used abrasive blasting hood should result in levels

below regulatory action limits. This however,

should not relieve the employer of responsibility to

implement engineering and work practice controls as

the primary control method. 

RECOMMENDATIONS

Welding in the Factory

The following recommendations are applicable only

for those areas evaluated; the ventilation

configuration in one work area may not be applicable

to another work area due to differences in the

welding operations and process layout.

(1) Investigate and implement, where feasible, fume

extraction guns for flux-cored arc welding processes,

particularly during welding operations which are

enclosed or semi-enclosed. Fume extraction guns

can only be used with continuous wire feed welding

operations such as FCAW, and are not available for

stick welding operations. For fume extraction guns

to be used successfully, the following concerns need

to be addressed:

(A) Educate welders on the proper use of the

fume extraction gun. For it to be used

efficiently, welders may need to adjust their

technique slightly to account for the added size

and weight of the gun.

(B) Ensure the ventilation is effectively

exhausting the welding fume without disturbing

the shielding gas. This requires a balancing of

the shielding gas flow rate and the ventilation

exhaust rate. Welders should be involved and/or

educated in the proper selection of exhaust rates

so that they do not modify the ventilation later

and potentially decrease the effectiveness of the

guns.

(C) Exhaust contaminated air to the outside and

practice preventive maintenance of the

ventilation system. This includes periodic

inspection of the welding gun nozzle to ensure

the exhaust orifices are not clogged. 

(2) Implement local exhaust ventilation in the

Factory for confined space welding operations.

While the blowers currently used may help to dilute

the welding fume concentration, the addition of an

exhaust system would help to reduce the amount of

fume in the immediate vicinity of the work area.

Mechanical exhaust ventilation might be provided by

routing 4"-8" flexible tubing into the work space and

connecting it to a portable local exhaust ventilation

unit. This type of setup would be adaptable to a

number of process configurations. The duct work

(tubing) for the ventilation system should not block

the welder’s means of access to and from the

confined work space. Duct adapters are available for

use with confined spaces.30

(3) Consider implementation of local exhaust

ventilation for welding operations throughout the

Factory. Due to the nature of the work in the

shipyard, it may not be possible to automate or

isolate certain welding processes. Stringent

shipbuilding specifications may also limit the use of

process substitutions. As such, the control of choice

at the shipyard may be ventilation. Considerations

before implementing controls include:

(A) Ensure the local exhaust ventilation system

does not obstruct movement and activities of the

overhead bridge crane, particularly in the Unit

Department. Possibilities include installing the

LEV system on a traversing rail along the

equipment lane or mounting the LEV system on

the structural posts in the equipment lane. One

manufacturer’s literature shows an articulating
Health Hazard Evaluation Report No. 97-0260-2716 Page 17

1. NIOSH [1992]. Recommendations for

occupational safety and health: compendium of

policy documents and statements. Cincinnati,

OH: U.S. Department of Health and Human

Services, Public Health Service, Centers for

Disease Control, National Institute for

arm unit which can be mounted on a carriage that

travels along an extraction rail (front reach of

about 14', 360 degree rotation).31

(B) Local exhaust ventilation systems should be

accessible from a variety of welding positions.

For example in the Unit Department, if the LEV

system is mounted on posts in the equipment

lanes, welding performed close to the middle of

the department, near the walkway, may not be

adequately controlled unless the articulating

arms can reach welding operations 60 feet away.

Since a reach that great may not be probable,

LEV systems would need to be positioned at

locations other than just the equipment lanes.

(4) Use welding curtains, screens, or tarps around

welding operations to help prevent welder’s flash

hazards, particularly in the Fabrication and Web

Departments. According to OSHA 29 CFR 1915.56,

whenever practicable, arc welding and cutting

operations shall be shielded by screens to protect

nearby personnel from the arc flash. If it is

impractical to place curtains or screens around the

welding operations, determine if they can at least be

positioned between work areas and the walkways to

protect nearby personnel from welder’s flash.

Workers adjacent to welding operations should use

long gloves and personal hoods to protect

themselves against unshielded welding flashes. 

(5) Continue participating in the NAVSEA

Emissions Working Group to learn of new control

ideas or successful ventilation efforts implemented in

other shipyards which may be applicable to

Avondale. 

(6) Evaluate specific welding tasks and implement

automation options where feasible. An example of

partial automation already observed in the shipyard

was that of the tripod welder which allowed the

welder to maintain some distance between himself

and the welding process. 

(7) Until a ventilation or other controls have been

implemented and comprehensively evaluated to

ensure effectiveness, respiratory protection should

continue to be used when welding in the Factory.

Supplied air respirators offering a higher degree of

protection should be used when working in confined

area such as the Inner Bottom Units, even if a forced

air blower is utilized.

Safety and Health Program

Avondale should ensure that Industrial Hygiene and

Safety review is obtained and incorporated during

the early conceptual or design phase for new or

remodeled facilities and processes. Anticipating

potential health and safety issues and providing for

appropriate controls and safeguards during the initial

planning stages of projects is an effective means of

preventing future problems and avoiding costly redesign and retrofits.

Employees should be encouraged to report all

potential work-related health symptoms to

appropriate health care personnel. Avondale should

monitor reported health complaints in a system

designed to identify particular job duties, work

materials, or areas which may be associated with

particular health effects.

Biologic monitoring for arsenic should allow for

specific determination of exposure to inorganic

arsenic, preferably by speciation of the arsenic in a

urine sample. Inorganic arsenic and its metabolites

can be distinguished from the non-toxic organic

arsenic found in seafood.

Continued collection of sputum samples as part of a

medical surveillance program for occupational

arsenic exposure is not of preventive medical value

and is no longer required by OSHA.

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Page 18 Health Hazard Evaluation Report No. 97-0260-2716

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10. NIOSH [1994]. NIOSH pocket guide to

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Prevention, National Institute for Occupational

Safety and Health, DHHS (NIOSH) Publication

No. 94-116.

11. Hathaway GJ, Proctor NH, Hughes JP

[1996]. Chemical hazards of the workplace, 4th.

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Company.

12. Clayton GD, Clayton FE [1978]. Patty's

Industrial Hygiene and Toxicology. Vol I --

General Principles, 3rd Revised Ed. New York:

John Wiley & Sons.

13. NIOSH [1992]. Alert: request for assistance

in preventing silicosis and deaths from

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DHHS (NIOSH) Publication No. 92-102.

14. NIOSH [1987]. Guide to industrial

respiratory protection. Cincinnati, OH: U.S.

Department of Health and Human Services, Public

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17. ATSDR [1993]. Toxicological profile for

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18. NTP [1998]. Eighth annual report on

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Page 20 Health Hazard Evaluation Report No. 97-0260-2716

Table 1

Personal Sampling Results - Welding: Gravimetric and Elemental

Avondale Shipyard Factory Building, Day Shift: HETA 97-0260

October 22, 1997

Task Monitored Sample

 #s

Minutes

Sampled

Contaminants Detected TWA Concentration

 mg/m3

 REL

 mg/m3

Track Welding on

Platen 40 at Pole

D-78, Arc Gouging

for 1.5 hours

3392

3362

1997

394

Total Weight (Gravimetric) 14.1 LFC

Lead 0.004 0.1

Arsenic <0.003 0.002 

Manganese 0.64 1.0

Iron 6.1 5.0

Copper 0.07 0.1

Chromium 0.01 0.5

Flux Core welding

on mild steel. Inner

Bottom Unit 26,

C3

3378

3406 416

Total Weight (Gravimetric) 14.4 LFC

Lead 0.003 0.1

Arsenic <0.003 0.002

Manganese 1.53 1.0

Iron 2.61 5.0

Copper 0.007 0.1

Chromium 0.005 0.5

Stick and Flux

Core welding on

mild steel. 

Platen 20, B3

3366

3395 427

Total Weight (Gravimetric) 3.15 LFC

Lead 0.003 0.1

Arsenic <0.002 0.002

Manganese 0.24 1.0

Iron 0.98 5.0

Copper 0.009 0.1

Chromium 0.002 0.5

Flux Core welding

on mild steel on

top of Platen 20,

B3, Unit 108

3404

3402 422

Total Weight (Gravimetric) 19.1 LFC

Lead 0.004 0.1

Arsenic <0.002 0.002

Manganese 2.1 1.0

Iron 4.2 5.0

Copper 0.01 0.1

Chromium 0.007 0.5
Table 1

Personal Sampling Results - Welding: Gravimetric and Elemental

Avondale Shipyard Factory Building, Day Shift: HETA 97-0260

October 22, 1997

Task Monitored Sample

 #s

Minutes

Sampled

Contaminants Detected TWA Concentration

 mg/m3

 REL

 mg/m3

Health Hazard Evaluation Report No. 97-0260-2716 Page 21

Flux Core Welding

in Inner Bottom -

confined area. 

Sampling

conducted for

duration of activity

3398 99 Total Weight (Gravimetric) 55.5 LFC

Lead 0.01 0.1

Arsenic <0.005 0.002

Manganese 7.33 1.0

Iron 12.5 5.0

Copper 0.01 0.1

Chromium 0.02 0.5

NOTES:

Gravimetric = Total weight of contaminants detected on filter

mg/m3 = milligrams of contaminant per cubic meter of air

TWA = time-weighted average concentration

All samples were field blank corrected

REL = NIOSH Recommended Exposure Limit for a 10-Hour TWA

LFC = Lowest Feasible Concentration

All Welders wore 1⁄2 mask air-purifying respirators with Dust-Mist-Fume filters or organic vapor cartridges with

pre-filters.
Health Hazard Evaluation Report No. 97-0260-2716

Table 2

Abrasive Blast House (Unit 265 and 106) Gravimetric Sampling Results

Inside and Outside Blast Hood, Passive: October 22-23, 1997

 Avondale Shipyards: HETA 97-0260

OH(A)

mg/m3

TWA

 OH(A)

OH(B) 

mg/m3

TWA 

OH(B)

TWA

OH(C)

Total

 mg

P(A)

mg

P(B)

mg

P(C)

mg

OH(C)

minus P(C)

IH 

mg/m3

WPF

OH-A/IH OH-C/IH

65.3

44.0

mg/m3

1253.1

538.6

mg/m3

582.6

mg/m3

271.6 0.51 1.07 1.58 579

mg/m3

0.24 183 2427.5

29.5 27.4

33.2 227.8

40.7

45.2

mg/m3

678.9

602.3

mg/m3

647.5

mg/m3

292.7 1.74 101.5 103.3 419.3

mg/m3

0.23 196 2817

57 240.9

32.5 1173.644.4

41.0

mg/m3

2538.1

1352.0

mg/m3

1393

mg/m3

571.2 ND 19.5 19.5 1345.6

mg/m3

0.20 205 6965

41.4 685.1

34.5 26.9

39.3

42.4

mg/m3

2626.6

1572.9

mg/m3

1615.3

mg/m3

851.2 5.1 25.35 30.45 1573.2

mg/m3

0.12 353 >10,000

56.3 1649.7

27.6 44.5
Table 2

Abrasive Blast House (Unit 265 and 106) Gravimetric Sampling Results

Inside and Outside Blast Hood, Passive: October 22-23, 1997

 Avondale Shipyards: HETA 97-0260

OH(A)

mg/m3

TWA

 OH(A)

OH(B) 

mg/m3

TWA 

OH(B)

TWA

OH(C)

Total

 mg

P(A)

mg

P(B)

mg

P(C)

mg

OH(C)

minus P(C)

IH 

mg/m3

WPF

OH-A/IH OH-C/IH

ort No. 97-0260-2716 Page 23

97.8

61.9

mg/m3

1181.6

516.8

mg/m3

578.7

mg/m3

273.5 0.31 2.96 3.27 571.7

mg/m3

0.07 884 8267

29.1 45.3

76.0 397.5

44.0

34.6

mg/m3

1234.8

1017.1

mg/m3

1051.7

mg/m3

457.7 0.38 17.72 18.1 1010.1

mg/m3

0.06 577 >10,000

29.0 1340.3

27.0 79.363.0

58.8

mg/m3

323.6

719.5

mg/m3

778.3

mg/m3

273.2 1.78 364.7 366.5 NC 0.12 490 6486

53.31 1242.6

67.7

41.9

mg/m3

287.8

250.3

mg/m3

292.2

mg/m3

125.9 2.12 ND 2.12 286.3

mg/m3

0.06 698 4870

28.4 301.2

18.1 63.3

74.5

47.6

mg/m3

10,910

5860.7

mg/m3

5908.3

mg/m3

2245.2 0.79 80.95 81.7 5691.9

mg/m3

<0.05 ND >10,000

38.4 4,555
Table 2

Abrasive Blast House (Unit 265 and 106) Gravimetric Sampling Results

Inside and Outside Blast Hood, Passive: October 22-23, 1997

 Avondale Shipyards: HETA 97-0260

OH(A)

mg/m3

TWA

 OH(A)

OH(B) 

mg/m3

TWA 

OH(B)

TWA

OH(C)

Total

 mg

P(A)

mg

P(B)

mg

P(C)

mg

OH(C)

minus P(C)

IH 

mg/m3

WPF

OH-A/IH OH-C/IH

Health Hazard Evaluation Report No. 97-0260-2716

20.7 230.3

48.0

57.1

mg/m3

2150

1753.5

mg/m3

1810.6

mg/m3

857.5 1.92 219 221 1344

mg/m3

0.05 1142 >10,000

57.7 1192.4

69.6 2002.8

48.6

64.1

mg/m3

1363.4

635.4

mg/m3

699.5

mg/m3

351.1 0.75 40.31 41.1 617.5

mg/m3

0.05 1282 >10,000

113.6 260.5

10.2 <.17

ter after removal of the loose bulk. OH = Outside Blast Hood Sample

bulk) removed from filter and analyzed separately P = “passive” sample, closed face filter, obtained outside Blast Hood

IH = Inside Blast Hood Sample

meter of sampled air. AB # = Abrasive Worker Individual Identifier Number

ND = No particulate present and sample was not analyzed.

as the ratio of the measured contaminant concentration outside the respirator face piece to the contaminant concentration inside the respirator face piece (OH-C/IH). The samples were taken

as being properly worn and used during normal work activities. Two sets of WPFs were calculated: OH-A/IH (using the smaller particle fraction concentration; OH-C/IH, using the total

or the duration of the workshift. The filter cassette was fixed to the workers lapel and the filter side cap removed. No air was drawn through the filter.

cause one OH sample was lost due to pump damage

worker was conducting compressed air blowdown and cleanup activities.

1 were sampled on October 23
ort No. 97-0260-2716 Page 25

Table 3

Abrasive Blast House (Unit 265 and 106) Elemental Sampling Results

Inside and Outside Blast Hood, Passive 

Avondale Shipyards: HETA 97-0260

October 22-23, 1997

OH(B), (mg/m3) OH(C), (mg/m3) P(A), (μg) P(B), (μg) P(C), (μg) OH(C) minus P(C) IH (μg/m3) WPF NIOSH REL

OH(A)/IH OH(C)/IH

AB #1

0.03 0.037 <0.2 <0.5 <0.5 0.037 mg/m3 <0.5 ND 0.1 mg/m3

<0.1 <0.1 <0.9 <3.0 <3.0 <0.1 mg/m3 <2.0 ND 2 μg/m3 (C)

1.49 1.7 1.4 1.6 3.0 1.7 mg/m3 1.0 210 1700 1.0 mg/m3

448.3 466.7 99 1000 1099 464.4 mg/m3 84.7 217 5510 5.0 mg/m3

0.89 0.93 0.23 0.31 0.54 0.92 mg/m3 0.17 235 5470 1.0 mg/m3

0.29 0.31 <0.2 <0.5 <0.5 0.31 mg/m3 (0.7) ND 0.5 mg/m3

AB #2

0.04 0.047 (0.2) 5.2 5.2 0.035 mg/m3 <0.7 ND 0.1 mg/m3

(0.02) (0.02) <0.9 <3 <3 (0.02) mg/m3 <3.0 ND 2 μg/m3 (C)

2.3 2.54 14 150 164 2.18 mg/m3 0.9 266 2822 1.0 mg/m3

431.6 450.2 2000 100,000 102,000 224.4 mg/m3 69.1 269 6515 5.0 mg/m3

0.54 0.59 2.3 70 72.3 0.43 mg/m3 0.16 312 3688 1.0 mg/m3

0.23 0.24 1.2 30 31.2 O.17 mg/m3 (0.7) ND 0.5 mg/m3

AB #3

0.06 0.069 <0.08 <0.2 <0.2 0.069 mg/m3 <0.5 ND 0.1 mg/m3

<0.1 (0.007) <0.9 <3 <3 (0.007) mg/m3 <2.2 ND 2 μg/m3 (C)

3.16 3.36 6.0 30 36 3.27 mg/m3 0.6 333 5600 1.0 mg/m3
Table 3

Abrasive Blast House (Unit 265 and 106) Elemental Sampling Results

Inside and Outside Blast Hood, Passive 

Avondale Shipyards: HETA 97-0260

October 22-23, 1997

OH(B), (mg/m3) OH(C), (mg/m3) P(A), (μg) P(B), (μg) P(C), (μg) OH(C) minus P(C) IH (μg/m3) WPF NIOSH REL

OH(A)/IH OH(C)/IH

Health Hazard Evaluation Report No. 97-0260-2716

1107.1 1123.5 750 14000 14750 1087.5 mg/m3 54 304 <10,000 5.0 mg/m3

1.2 1.25 1.2 9.8 11.0 1.22 mg/m3 0.20 250 6250 1.0 mg/m3

0.06 0.62 (0.3) 4.2 4.2 0.61 mg/m3 (0.7) ND 0.5 mg/m3

AB #4

0.29 0.30 (0.5) (0.1) (0.5) 0.3 mg/m3 <0.4 ND 0.1 mg/m3

0.03 0.03 <0.9 <3.0 <3.0 0.03 mg/m3 <1.9 ND 2 μg/m3 (C)

8.6 8.81 31 43 74 8.67 mg/m3 0.5 420 >10,000 1.0 mg/m3

689.2 704.7 2500 24,000 26,500 653.9 mg/m3 39.5 392 >10,000 5.0 mg/m3

1.7 1.75 3.7 15 18.7 1.71 mg/m3 0.12 416 >10,000 1.0 mg/m3

0.6 0.62 2.2 3.6 5.8 0.61 mg/m3 (0.6) ND 0.5 mg/m3

AB #5

0.04 0.05 (0.06) <0.08 (0.06) 0.05 mg/m3 <0.7 ND 0.1 mg/m3

(0.01) (0.01) <0.9 <3 <3 (0.01) mg/m3 <0.21 ND 2 μg/m3 (C)

2.18 2.51 1.2 0.83 2.03 2.51 mg/m3 0.2 1650 >10,000 1.0 mg/m3

312.2 341.4 69 3000 3069 333.6 mg/m3 20.4 1431 >10,000 5.0 mg/m3

0.63 0.72 0.19 0.84 1.03 0.72 mg/m3 (0.02) ND 1.0 mg/m3

0.24 0.26 <0.2 <0.5 <0.5 0.26 mg/m3 (0.5) ND
Table 3

Abrasive Blast House (Unit 265 and 106) Elemental Sampling Results

Inside and Outside Blast Hood, Passive 

Avondale Shipyards: HETA 97-0260

October 22-23, 1997

OH(B), (mg/m3) OH(C), (mg/m3) P(A), (μg) P(B), (μg) P(C), (μg) OH(C) minus P(C) IH (μg/m3) WPF NIOSH REL

OH(A)/IH OH(C)/IH

ort No. 97-0260-2716 Page 27

AB #6

0.02 0.026 <0.2 <0.8 <0.8 0.026 mg/m3 <1.0 ND 0.1 mg/m3

(0.09) (0.09) <0.9 <3 <3 (0.09) mg/m3 (3.8) ND 2 μg/m3 (C)

2.7 2.89 3.0 38 41 2.80 mg/m3 0.5 380 5780 1.0 mg/m3

865.1 880.3 1500 17,000 18,500 837.8 mg/m3 33.3 456 >10,000 5.0 mg/m3

0.82 0.85 1.4 15 16.4 0.81 mg/m3 (0.04) ND 1.0 mg/m3

0.47 0.49 <0.2 14 14 0.46 mg/m3 <0.4 ND 0.5 mg/m3

AB #7

0.02 0.026 (0.2) 3.5 3.5 NC <0.8 ND 0.1 mg/m3

0.03 0.03 <0.9 (20) (20) NC <1.9 ND 2 μg/m3 (C)

3.4 3.8 100 720 820 NC 0.8 500 4750 1.0 mg/m3

486.7 515.4 17,000 360,000 377,000 NC 50.5 568 >10,000 5.0 mg/m3

0.6 0.67 12 310 322 NC (0.04) ND 1.0 mg/m3

0.3 0.32 4.8 160 164.8 NC <0.4 ND 0.5 mg/m3

AB #8

0.008 0.01 0.12 NA 0.12 0.009 mg/m3 <0.6 ND 0.1 mg/m3

<0.02 (0.002) <0.9 NA <0.9 ND mg/m3 <2.6 ND 2 μg/m3 (C)

1.01 1.23 5.7 NA 5.7 1.22 mg/m3 0.6 367 2050 1.0 mg/m3
Table 3

Abrasive Blast House (Unit 265 and 106) Elemental Sampling Results

Inside and Outside Blast Hood, Passive 

Avondale Shipyards: HETA 97-0260

October 22-23, 1997

OH(B), (mg/m3) OH(C), (mg/m3) P(A), (μg) P(B), (μg) P(C), (μg) OH(C) minus P(C) IH (μg/m3) WPF NIOSH REL

OH(A)/IH OH(C)/IH

Health Hazard Evaluation Report No. 97-0260-2716

172.3 190.3 420 NA 420 189.3 mg/m3 41.1 438 4630 5.0 mg/m3

0.23 0.29 0.91 NA 0.91 0.29 mg/m3 (0.03) ND 1.0 mg/m3

0.11 0.13 (0.2) NA (0.2) 0.13 mg/m3 <0.6 ND 0.5 mg/m3

AB #9

0.07 0.071 (0.3) 0.81 0.81 0.07 mg/m3 <0.5 ND 0.1 mg/m3

<0.03 (0.007) <0.9 (3) (3) ND mg/m3 <2.4 ND 2 μg/m3 (C)

6.4 6.68 6.0 280 286 5.9 mg/m3 <0.1 ND 1.0 mg/m3

1926 1944.5 1100 82,000 83,100 1725.8 mg/m3 5 3700 >10,000 5.0 mg/m3

2.4 2.44 1.6 75 76.6 2.24 mg/m3 <0.08 ND 1.0 mg/m3

1.23 1.25 (0.4) 50 50 1.12 mg/m3 <0.05 ND 0.5 mg/m3

AB #10

0.08 0.08 <0.2 (100) (100) 0.08 mg/m3 <0.5 ND 0.1 mg/m3

0.05 0.05 <0.9 <3 <3 0.05 mg/m3 <0.21 ND 2 μg/m3 (C)

8.27 8.63 18 490 508 7.56 mg/m3 0.4 900 >10,000 1.0 mg/m3

1201.3 1222.8 1100 210,000 211,000 777.28 mg/m3 30.9 696 >10,000 5.0 mg/m3

1.55 1.6 1.5 170 171.5 1.24 mg/m3 (0.05) ND 1.0 mg/m3

0.68 0.7 0.88 100 100.88 O.49 mg/m3 (0.05) ND 0.5 mg/m3
Table 3

Abrasive Blast House (Unit 265 and 106) Elemental Sampling Results

Inside and Outside Blast Hood, Passive 

Avondale Shipyards: HETA 97-0260

October 22-23, 1997

OH(B), (mg/m3) OH(C), (mg/m3) P(A), (μg) P(B), (μg) P(C), (μg) OH(C) minus P(C) IH (μg/m3) WPF NIOSH REL

OH(A)/IH OH(C)/IH

ort No. 97-0260-2716 Page 29

AB #11

0.03 0.031 (0.2) (0.2) (0.2) ND <0.5 ND 0.1 mg/m3

0.04 0.048 <0.9 <0.3 <0.9 ND <2.3 ND 2 μg/m3 (C)

5.14 5.54 8.5 88 96.5 5.35 mg/m3 0.2 2000 >10,000 1.0 mg/m3

463.8 493 1000 40,000 41,000 411.3 mg/m3 13.0 2246 >10,000 5.0 mg/m3

0.77 0.84 1.0 22 23 0.79 mg/m3 <0.08 ND 1.0 mg/m3

0.38 0.41 (0.3) 15 15 0.38 mg/m3 <0.5 ND 0.5 mg/m3

e as those described in Table 1 for the corresponding abrasive blaster individual identifier number. All reported values are time-weighted average

 meter (mg/m3) except for the passive samples (mass only) and IH sample (micrograms per cubic meter [μg/m3]). All employees wore a half-mask air

n addition to the blast hood.

ate the contaminant concentration was between the analytical limit of detection (LOD) and the limit of quantification (LOQ).

OH = Outside Blast Hood Sample

ion (loose bulk) removed from filter and analyzed separately P = “passive” sample, closed face filter, obtained outside Blast Hood

IH = Inside Blast Hood Sample

l Identifier Number 

n determined by subtracting the contaminant mass detected on the passive filter from the total contaminant mass detected on the outside the blast hood

efined as the ratio of the measured contaminant concentration outside the respirator face piece to the contaminant concentration inside the respirator face

 samples were taken simultaneously while the respirator was being properly worn and used during normal work activities.

ed because one OH sample was lost due to pump damage.
Page 30 Health Hazard Evaluation Report No. 97-0260-2716

Table 4

Avondale Shipyards: HETA 97-0260

Paired Bulk Sample Results - Steel Grit from Shot House. All Results in μg/g

Description As Pb Cr Cu Mn Fe

ACS DC ACS DC ACS DC ACS DC ACS DC ACS DC

1A/1B: South Pot, Recycle Grit 74.1 43 4.5 3 529.3 470 942.5 680 3529 2300 949K 106

2A/2B: South Side, Coarse Reject 49.1 40 65.8 29 519 640 1518 950 6909 3400 683K 800K

3A/3B: South Side, Fine Reject 30.2 16 223.4 190 408.9 320 1035 910 6486 5600 385K 360K

4A/4B: North Side, Recycle Grit 41.3 39 4.3 1.4 264 270 836 770 1104 2100 953K 990K

5A/5B: North Side, Coarse Reject 32.1 41 25.5 7.4 418.6 290 909.5 790 4607 2599 743K 870K

6A/6B: North Side, Fine Reject 16.1 12 35.2 71 463.5 270 1155 640 9703 7200 526K 320K

7A/7B: Inside Shot House Floor 41.7 46 6.5 1.5 464.6 240 791.5 810 2174 1700 958K 106

8A/8B: Virgin Shot - G40 Steel

Grit

31.9 30 5.9 ND 149.1 ND 698.2 430 912 1200 962K 870K

ACS = NIOSH Analytical Chemistry Services (Analysis by Inductively Coupled Plasma Emission

Spectroscopy)

DC = Data Chem (Analysis by Atomic Absorption Spectroscopy)

μg/g = microgram of contaminant per gram of sample, equivalent to part per million (ppm).

No cadmium detected in either sample set

As = arsenic

Pb = lead

Cr = Chromium

Cu = Copper

Mn = Manganese

Fe = Iron
Health Hazard Evaluation Report No. 97-0260-2716 Page 31

APPENDIX A: SAMPLING AND ANALYTICAL

METHODOLOGY

Processes selected for monitoring were based on an assessment of employee work activities and controls utilized.

Activities of concern noted by the HHE requesters were also targeted for sampling. The monitoring was conducted

utilizing established analytical protocols (NIOSH analytical methods).1

 Calibrated air sampling pumps were

attached to selected workers and connected, via tubing, to sample collection media placed in the employees'

breathing zone. A primary standard was used to calibrate the air sampling pumps. Monitoring was conducted

throughout the employees' work-shift. After sample collection, the pumps were post-calibrated and the average

of the pre- and post-calibration flow rates were used to determine the sample volume. All air samples were

submitted to the NIOSH contract laboratory (Data Chem, Salt Lake City, Utah) for analysis. Field blanks were

submitted with the samples and all reported results were blank corrected. Specific sampling and analytical

methods used during this survey were as follows:

Welding Fume

Personal exposures to airborne welding fume were monitored using Gilian HFS 513A or Gil-Air sampling pumps.

Flow rates of approximately 2 liters per minute (l/m) were used to obtain the samples. The samples were collected

on tared 37 millimeter (mm),5 micrometer (:m) pore size, poly-vinyl chloride (PVC) filters in the closed-face

mode, and analyzed gravimetrically to determine the total welding fume concentration according to NIOSH

Method 0500. An element specific analysis was also conducted on the samples, according to NIOSH Method

7300, to differentiate and quantify the following metal species: lead, iron, chromium, arsenic, manganese, and

copper. With this technique, the sample filters are microwave digested in an acid mixture, and analyzed with a

regular inductively coupled plasma emission spectrometer (ICAP). Additionally, all samples found to be

nondetected for lead using the regular ICAP were reanalyzed using a trace ICAP. These reanalyses were

conducted to verify that the nondetected values for lead were not the result of the dilutions necessary to overcome

the high iron concentrations present on the samples.

Abrasive Blasting

Personal breathing zone (PBZ) monitoring during abrasive blasting activities was conducted to evaluate exposure

to total particulate and the following metal species: lead, iron, chromium, arsenic, manganese, copper, using the

same methods as that described for welding fume. For each abrasive blaster monitored, samples were collected

in three locations: inside the blast hood, outside the blast hood, and a “passive” sample outside the blast hood. 

The inside the blast hood samples were obtained by connecting the air sampling pump to the worker and attaching

the filter to the inside of the blast hood using a Helmet Sampling Adaptor (SKC, Inc., Cat.# 225-600) to position

the sampling cassette adjacent the workers’ breathing zone. The pump was activated just prior to the worker

donning the blast hood and entering the Shot House. Sampling was conducted for the duration of the work shift.

The outside the blast hood samples were collected by attaching the filter cassette to the abrasive blast shroud.

Because of the anticipated high loading on the filters, the cassettes were changed out every 1 - 1.5 hours (whenever

the worker exited the Shot House). Time-weighted average concentrations were calculated using the following

formula:
Page 32 Health Hazard Evaluation Report No. 97-0260-2716

1. NIOSH [1994]. NIOSH manual of analytical methods, 4th ed. Eller, RM, ed. Cincinnati, OH: U.S.

Department of Health and Human Services, Public Health Service, Centers for Disease Control and

Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113.

TWA (milligrams/cubic meter) = C1T1 + C2T2 + CnTn

 T1 + T2 + Tn

Where: C1T1 = concentration measured during sampling period T

The passive samples were collected by attaching a 4 inch length of Tygon tubing to a filter cassette containing a

tared 37 mm, 5 :m pore size poly vinyl filter. The tubing and cassette was then secured to the outside of the

abrasive blast shroud and the inlet cap removed (closed face mode). The filter cassette was worn by the worker

for the duration of the work shift. 

On both the passive and outside the hood samples, the larger size fraction (loose grit) was removed from the filter

and analyzed (gravimetrically and elementally) separately. Although a rigorous definition and size range for this

larger particulate size fraction was not determined, the larger particles removed and analyzed separately are

believed to consist primarily of rebound or inertia driven shot and not in a size range considered to present an

inhalation hazard. For each filter portion analyzed from the outside the hood sample, TWA concentrations were

calculated. The two measurements were then combined to calculate the total concentration. Because no air was

drawn through the passive monitor, only the total weight (milligrams) was reported.

Bulk Samples

Eight steel grit bulk samples in duplicate were collected from the Shot House in wide-mouth polyethylene

containers to determine the concentration of the following elements: lead, iron, arsenic, cadmium, chromium,

copper, and manganese. One sample from each pair was shipped to the NIOSH contract laboratory (DataChem,

Salt Lake City, Utah) and the companion sample shipped to the NIOSH laboratory (ACS) for analysis. The purpose

of the paired sampling was to address potential analytical problems associated with quantifying low concentrations

of lead in a sample that is predominantly iron using ICAP as the analytical method. In addition to the steel grit

samples, a bulk sample of the mild steel used in the factory, and both components of a 2-part epoxy resin used as

a pre-construction primer prior to welding and abrasive blasting were submitted to ACS for elemental analysis.

At the NIOSH contract laboratory, an aliquot from each sample was digested and analyzed by graphite furnace

atomic absorption spectrometry (AAS). Because of high iron concentrations, some samples required dilutions up

to 1000X. At ACS, an aliquot of each sample was analyzed by ICAP according to NIOSH Method #7300. To

determine recovery data, Standard Reference Material 364 (high carbon steel) from the National Institute for

Standards and Technology (NIST) was found to be the best available match to the samples. The air samples were

placed on hold until the results of the bulk sampling were available.

References
Health Hazard Evaluation Report No. 97-0260-2716 Page 33

APPENDIX B: CONTROL OF WELDING FUME

To reduce the hazard of welding fume exposures, the following hierarchy of controls should be considered:

automation, substitution, isolation, ventilation. 

! Partial or complete automation so the welder is less exposed to welding fumes. 

! Implement process changes to limit hazards. For example, determine if different joining process other than

welding can be used, if lower fume-producing welding processes, such as submerged arc welding or gas

tungsten arc welding (GTAW or TIG) are feasible; or if low-fume electrodes can be substituted for the

electrodes currently used.

! Isolate or enclose the welding process to limit the hazard to workers. 

! Utilize ventilation to remove the fumes and gases from the welder’s breathing zone. 

A number of ventilation systems are commercially available to help control fume emissions during welding

operations. Local exhaust ventilation (LEV) controls capture the air contaminants directly at the point of

generation and are generally positioned no more than 12 inches away from the source. LEV systems are more

effective than general ventilation systems since the air contaminants can be captured and removed before they can

reach the welder’s breathing zone. However, the effectiveness of the LEV system is often dependent on how the

welder positions the hood; if the hood is placed too far from the welding operation it may not adequately capture

the air contaminants, depending on the capture velocity. LEV systems used during industrial welding operations

can include: fixed movable hoods, portable movable hoods, fume extraction guns, and, to some extent, canopy

hoods. 

Movable Hoods

OSHA 29 CFR 1910.252 recommends that “(movable hoods) should be placed as near as practicable to the work

being welded and provided with a rate of airflow sufficient to maintain a velocity in the direction of the hood of

100 fpm in the zone of welding when the hood is at its most remote distance from the point of welding.” To

maintain a capture velocity of 100 fpm, OSHA provides the following values when using a 3" wide, flanged hood.

OSHA GUIDELINES FOR MOVABLE HOOD AIRFLOW RATES

Distance from Arc to Hood (in) Airflow 

(cfm)

Duct Diameter 

(in)

4-6 150 3

6-8 275 3.5

8-10 425 4.5

10-12 600 5.5
Page 34 Health Hazard Evaluation Report No. 97-0260-2716

The ACGIH Ventilation Manual also provides guidelines on the use of movable exhaust hoods for welding

operations.1

 The airflow rates suggested by ACGIH are more conservative than those recommended by OSHA.

ACGIH GUIDELINES FOR MOVABLE HOOD AIRFLOW RATES

Distance from Arc to Hood 

(in)

Plain Duct

Airflow (cfm)

Flange or Cone Hood

Airflow (cfm)

up to 6 335 250

6-9 755 560

9-12 1335 1000

Fume Extraction Guns

Fume extraction guns are high vacuum, low volume controls. Two types of fume extraction guns are available.

One type of gun incorporates the ventilation directly into the gun design. Lines for the shielding gas and exhausted

air are encased in a large, single line leading from the gun. The second type of gun uses a conventional,

nonventilated model with a suction attachment connected to the gun nozzle. On this model, the shielding gas and

exhausted air lines remained separate. The type of gun used often depends on the welder’s personal preference.

Welders who find the all-in-one fume extraction gun bulky and cumbersome may prefer to use a conventional gun

with the suction attachment. One manufacturer gives the following comparison of airflow rates for fume extraction

guns and suction devices.2

 APPROXIMATE AIRFLOW RATES FOR LEV SYSTEMS

Suction Device Approximate Airflow 

Requirement (cfm)

Fume Extraction Gun 20-60

Small Suction Hood 40-80

Large Suction Hood 80-160

Although local exhaust ventilation can be very efficient at reducing worker welding fume exposures, there are

many impediments to the successful implementation of this type of ventilation control in the shipbuilding industry:

(1) Controls must be usable in confined or enclosed spaces, or in awkward positions.

(2) Controls must be usable by a mobile workforce and may require extensive reaches.

(3) Controls must be able to be moved out of the way of overhead cranes and hoists when necessary.

(4) Duct work for controls must be tough enough to endure misuse and abuse.

(5) Controls must be able to effectively filter exhaust air before releasing it back into the welding area, or must

exhaust air to the outside (preferrable).

(6) Controls must be flexible enough to adjust to changes in unit size and configuration, or changes in the

process layout.
Health Hazard Evaluation Report No. 97-0260-2716 Page 35

1. ACGIH [1992]. Industrial ventilation: a manual of recommended practice. 21st Ed. Cincinnati, Ohio.

American Conference of Governmental Industrial Hygienists.

2. Lincoln Electric [1994]. Lincoln Environmental Systems. High-Vacuum Solutions. Fume X-TractorTM

Products. Product Literature, E13.10. Cleveland, OH

There can be additional drawbacks to using the various types of local exhaust ventilated controls. For example,

welders may resist using fume extraction guns if they consider them to be too cumbersome or if they believe the

ventilation is exhausting the shielding gas in addition to the fumes. Movable hoods are only effective if welders

continually position the hood close to the point of fume generation. Portable ventilated units may be too large to

maneuver through the work in progress on the Factory floor.

If local exhaust ventilation controls cannot be implemented, general exhaust ventilation (GEV) controls should be

considered. A drawback to a GEV system is that, although it may help to reduce overall fume levels in the facility,

it may not have a significant impact on reducing the exposure levels of the welder. OSHA 29CFR1910.252

recommends a minimum exhaust ventilation rate of 2000 cfm per welder when welding in a space of less than

10,000 ft3

 per welder, or when in a room with a ceiling height of less than 16 ft, or when in confined spaces or

where the welding space contains structural barriers to the extent that they significantly obstruct cross ventilation.

The ACGIH Ventilation Manual suggests the following general ventilation airflow rates: (1) for open areas where

welding fume can rise away from the breathing zone the airflow required (cfm) = 800 x lb/hour of rod/wire used;

(2) for enclosed areas or positions where fume does not readily escape the breathing zone the airflow required (cfm)

= 1600 x lb/hour of rod/wire used. Examples of general exhaust ventilation controls include: suspended air

filtration units and roof ventilators. 

Other Welding Fume Controls

In addition to engineering controls, other factors such as work practices, personal protective equipment, and

administrative controls should be investigated to help reduce worker exposures to welding fumes. Examples of

work practices that may help to lower worker fume exposures include: educating welders to keep their heads out

of the weld plume and to remain aware of air currents to ensure welding is performed upwind of the fumes as much

as possible. Examples of personal protective equipment include: proper use of respirators, use of welding

glasses/goggles/hoods by welders and workers in the vicinity, and availability of welding screens to place around

weld operations. Examples of administrative controls include: job rotation to limit welders’ exposures, training

and education of welders on hazards and controls associated with their jobs, ensuring welders use ventilation and

other control measures supplied to them.

References
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