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International Journal of Industrial Ergonomics 44 (2014) 131e139

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International Journal of Industrial Ergonomics

journal homepage: www.elsevier .com/locate/ergon

Designing an improved respirator for automotive painters

Alma Maria Jennifer A. Gutierrez*, Melissa D. Galang, Rosemary R. Seva, Michelle C. Lu,Diana Rose S. TyIndustrial Engineering Department, De La Salle University, Manila, Philippines

a r t i c l e i n f o

Article history:Received 28 February 2013Received in revised form15 October 2013Accepted 24 November 2013Available online 18 December 2013

Keywords:RespiratorAnthropometrySpray paintingProduct designSilicon

* Corresponding author. Tel.: þ63 25244611; fax: þE-mail address: alma.gutierrez@dlsu.edu.ph (A.M.

0169-8141/$ e see front matter � 2013 Elsevier B.V.http://dx.doi.org/10.1016/j.ergon.2013.11.004

a b s t r a c t :

In this study four types of respirators used by auto painters in a certain company were evaluated usinggap analysis in twelve features specified by OSHA, work observation, and OSHA’s fit test standard. Gapanalysis showed that top reasons for dissatisfaction include odor filtration, strap adjustment, filtration ofparticles, and ease of breathing. Discomfort and poor fitting were cited as common reasons for notwearing respirators at work when users were observed. A prototype respirator was developed consid-ering relevant facial anthropometry gathered from auto painters in the company. The new respiratorused headband design for straps, silicone as material, and a single cartridge for odor filtration. Theprototype was evaluated using the same methods employed in the evaluation process. The acceptabilityof the prototype was evaluated in twelve aspects. Results showed that users were significantly satisfiedwith the prototype in all features evaluated except for weight. The prototype was heavier than two of therespirators evaluated. The contour developed based on the facial anthropometry of users was able to lockthe spaces along the side of the face sealing out harmful odor from the environment.

Relevance to industry: This procedure described in this study may be used by respirator designers indeveloping new designs. Alternative ways of evaluating the comfort and effectiveness of respiratorspresented in the study may be used by companies in choosing respirators to buy in the market

� 2013 Elsevier B.V. All rights reserved.

1. Introduction

Workers in the painting industry are exposed to many respira-tory hazards that require them to use respirators. Respirators aregenerally used to reduce workers’ exposure to airborne contami-nants such as dust, mists, fumes and vapors that are harmful tohealth. Negligence in using a respirator or improper usemay lead tohealth problems such as asthma, nose and eye irritation, dizziness,headache, etc. (Health and Safety Executive, 2009,Workcover NSW,2001).

Respirators in the market can be generally classified as air-purifying respirator (APR) or atmosphere-supplying respirator(ASP). APR’s remove contaminants from the air while ASP’s provideclean air for breathing from an uncontaminated source (Cal/OSHAConsultation Service, 2005). The safety performance of a respi-rator and the level of protection provided when worn in theworkplace are affected bymany factors including fitness to the user,the task, adequacy of the respirator to filter the contaminants,training of the user, and maintenance of the respirator (Claytonet al., 2002). The use of a respirator is part of a company’s

63 25240563.J.A. Gutierrez).

All rights reserved.

respiratory protection program, which includes selection of properrespirator for the task and training employees regarding appro-priate use (Occupational Safety and Health Administration, 2002).

The most common respirator used by painters in the Philippinesis the APR. It has filters, cartridges, or canisters that remove con-taminants from the air before it reaches the user (Rajhans andPathak, 2002). They do not supply oxygen and should thereforenot be used in oxygen-deficient environments. OSHA has identifiedthree types of air-purifying respirators according to function: (1)particulate respirators, (2) combination respirators, and (3) gas andvapor respirators. They can be further classified in terms of the typeof its face piece such as: (1) disposable respirator, (2) quarter-face(single-cartridge) respirator, (3) half-face (double-cartridge)respirator, and (4) full-face respirator. The right choice of the facepiece is dependent on the environment where the respirator will beused (Bollinger and Schutz, 1987).

1.1. Literature review

The respirator is a type of personal protective equipment (PPE)that is designed to protect workers from occupational hazards.However, the use of PPE has many associated problems foremost ofwhich is the lack of comfort or fit (Lombardi et al., 2009). Akbar-

Fig. 1. Respirators available in the market.

Table 1Attributes of current respirators.

Attributes Respirator

1 2 3 4

Number of cartridge Single Double Double DoubleCartridge type Organic Organic Organic OrganicFace piece material Silicon Rubber Rubber RubberStrap material Garter Garter Garter GarterWeight (lbs) 1.30 0.89 2.45 3.02Horizontal dim (cm) 10.50 10.50 9.50 12.00Vertical dim (cm) 13.00 13.50 13.50 12.00Strap length (cm) 50.50 80.00 101.00 85.00

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Khanzadeh et al. (1995) documented that in an automobileencapsulating plant more than half of respirator users (62%) ratedtheir respirators as uncomfortable. Since workers have diversefacial features and sizes it is very difficult to find a respirator thatwill be comfortable for everyone (Occupational Safety and HealthAdministration, 2002). It is for this reason that employers areencouraged to provide different kinds of respirators that should beavailable for selection.

The problem of respirator facial fitting is related to the sizeand shape of the face. In the US, Zhuang et al. (2010a) con-ducted a head and face anthropometric survey of civilianrespirator users to determine components of facial variability.Four principal components were identified that may be used toimprove respirator fit-test standards. Zhuang et al. (2010b) alsodeveloped five 3-D head forms from facial anthropometric dataof the US workforce for respirator certification standards andresearch. Using the Civilian American and European SurfaceAnthropometry Resource (CAESAR) database Fenlon (2007)generated 3D facial models to evaluate the fit of a half-maskrespirator. In the study, fit was assessed based on the distancebetween the face and landmark points of the mask. Resultsshowed that the average face generated for Asian subjects hadthe best fit. In Korea, Han et al. (2004), developed three half-mask face pieces to address face-seal leakage problems ofavailable respirators in the market. Korean facial anthropom-etry was used to generate face models that were used as basesof the proposed designs.

Previous studies showed that facial anthropometry has signifi-cant variability. Yang et al. (2007) found that facial anthropometryof Chinese and Americans are different. Chinese have wider andshorter facial character compared to Americans. Zhuang et al.(2010c) concurred with these findings highlighting significantfacial anthropometric differences between Caucasians, African-Americans, Hispanics, and Asians. As such, respirator fit testpanels have been developed by Chen et al. (2009) to accommodateat least 95% of Chinese workers.

In the Philippines, Cheng et al. (1999) improved the designof APR’s used by painters in a certain company. Four kinds ofAPR’s used were evaluated based on identified requirements ofthe users. Difficulties documented include poor fit, difficulty inbreathing, and moisture formation inside the mask. Theredesigned facemask featured a reduction in the height of theface piece and the weight of the filter. The area allocated for airintake in the mask was also increased for better air circulation.The prototype designed by Cheng et al. (1999), however, wasnot mass-produced and is not currently available in themarket.

In the present study, APR’s used in an automotive paintingcompany were evaluated for the purpose of generating a newdesign that will enhance user satisfaction and promote the use ofAPR in the company.

2. Product analysis

In order to identify areas for improvement in the design ofcurrent respirators in the market, a combination of researchmethods was employed in the study. These methods aimed todetermine the problems faced by the users and the causes of theseproblems in terms of design.

2.1. Survey

A survey was conducted among 85 male auto painters from acertain automotive painting company. The participants use sprayguns for painting. The painting activity is done inside a sprayingbooth to protect the part from dusts or unwanted particles. Thespray booth is like an oven that is not well ventilated. The averageage of the participants is 32.5 years. Their task involves paintingmotorcycle parts mainly done during the day.

The survey aims to identify the unmet needs of the participantsin the respirator they are currently using and those that are avail-able in the market as shown in Fig. 1. A detailed description of therespirators is given in Table 1. Among the respirators evaluated,respirator 1 is the only single cartridge respirator with a face piecemade of silicon. Although it only has a single cartridge it is not thelightest or the smallest in terms of face piece dimension. Respira-tors 2e4 are made of rubber and have double cartridges. Respirator2 is the lightest among the four despite of its relatively large hor-izontal and vertical dimensions. Straps of all respirators aremade ofgarter.

All respirators were assessed by asking participants to rate thesatisfaction with respect to the features. The features were alsorated in terms of importance to the users. Satisfaction and impor-tance were rated using a 5-point Likert scale (5 e very satisfied/very important and 1 e not at all satisfied/not important at all).Participants were required to use the four respirators while work-ing for a period of one day.

A checklist of features was used in the assessment to ensurecomprehensiveness. The items on the checklist were taken from

A.M.J.A. Gutierrez et al. / International Journal of Industrial Ergonomics 44 (2014) 131e139 133

OSHA Standards regarding the Respiratory Protection Program1910.134 (Occupational Safety and Health Administration, 1998).The features and definitions of the items on the checklist areenumerated as follows.

� Ease of breathingeworker is able to breathe freely evenwith theuse of respirator.

� Ease of communication e worker is able to communicate withother workers and other workers are able to hear them properly.

� Skin comfort (itchiness, irritation, marks left on skin) e workersare comfortable with the type of respirator given to them. Therespirator is considered comfortable to the skin if it does notcause irritation and does not leave mark on the nose and/orcheeks area even after long hours of usage.

� Weight of the respirator e the weight of the respirator that issubject for the workers to carry during long working hours.

� In-respirator temperature e the temperature inside the respi-rator (i.e. hot or cold); subject to air circulation inside therespirator.

� In-respirator humidity e the moisture content inside the respi-rator; this is formed due to high temperature inside therespirator.

� In-respirator odor circulation e the odor inside the respirator.� Filtration of odor from substances e the ability of the cartridge tofilter the air inhaled by the workers as well as the ability of therespirator to air lock the smell of the paint.

� Filtration of particles from substances e the filtration level of thecartridge that blocks the penetration of paint fumes and othersubstances into the face piece.

� Strap adjustments e straps are adjusted according to wearer’spreference and comfort.

� Contour of face piece e the shape of the face piece; does therespirator’s contour follow the bone structure in the nose andcheek area of the face?

� Service life e the length of life of the respirator� Visual range e the range of sight of the workers while using therespirator

Performance gap analysis method was used to compare actualperformance with the theoretical target (Gitlow et al. 1995). In thiscase, the satisfaction of the auto painters with the current respi-rators being used in the company is compared to the features orattributes that the auto painters consider important in a respirator.The objective is to understand user’s expectation of a product andevaluate an existing one based on these expectations.

With the checklist, the participants were asked to indicate rat-ings of satisfaction and importance beside each feature. Theaverage ratings of satisfaction and importance were computed foreach feature. Performance gap was computed by using the formulaproposed by Gitlow et al. (1995).

Table 2Performance gap analysis.

Attribute Imp Sat1 Gap 1 Sat2

Filtration of odor 3.81 2.45 �1.36 2.75Strap adjustments 3.56 3.01 �0.55 3.18Filtration of particles 3.36 3.37 0.01 3.02Ease of breathing 3.64 3.69 0.06 3.06Skin comfort 2.86 2.80 �0.06 2.79Contour face piece 2.77 2.71 �0.06 2.78In mask humidity 2.86 2.89 0.04 2.88In mask odor circulation 2.84 2.95 0.12 3.02In mask temperature 2.59 2.87 0.29 2.72Ease of communication 2.41 2.84 0.43 2.98Visual range 2.65 3.17 0.52 3.31Weight of mask 2.41 2.84 0.43 3.46

Performance Gap ¼ Satisfactionð%Þ � Importanceð%Þ

A positive performance gap on an item indicates that the current

respirator is meeting the expectations of the auto painters withrespect to the particular item category. A negative performancegap, however, indicates that the current respirator being used is notmeeting the desired performance of the painters for the particularitem. The result of performance gap analysis is shown in Table 2.The importance rating was derived by getting the average of allratings given by participants on that attribute. This rating wascompared to the satisfaction ratings given for each of the respiratorto derive Gap 1 to Gap 4. The attribute that has the highest gap isthe ability of the respirator to filter odors and strap adjustments.The straps are too thin and cannot be adjusted to fit the mask to theface. Strap widths vary from 1 to 1.5 cm. Participants are generallysatisfied with the weight of the mask and the visual range providedwhile in use.

2.1.1. Work observation techniqueAside from the survey, workers were also observed in the

workplace to determine if they are using the personal protectiveequipment issued to them. Three observers were alternately sent tothe site to observe at different times without their knowledge.Work sampling was done for one week. Workers were observed atintervals of 1 h and 15 min within their 24-h daily operation for anentire week’s operation that is 5 days. They were observed in theiractual place of work. During the observation, the number of timesthat a worker does not wear the respirator while working wasrecorded. These workers were interviewed at the end of their shiftwith the following questions.

� Why did you remove the respirator while still working?� How long have you been working before you removed therespirator?

The worker’s status in the company (permanent or contractual)and work experience was also considered in the analysis. It is hy-pothesized that contractual workers may have not been adequatelytrained on safety practices or have not acquired good safety habits.

Results of the observation showed that the number of workersnot wearing their respirators at work increases as their shiftprogress. On the average 41% of workers per shift did not wearrespirators. Only 18% of these workers are contractual. The mainreason given for not wearing the respirator was discomfort.

2.2. Fit test

For each of the four respirators, a fit test was conducted todetermine effectiveness in terms of protection and comfort. Ac-cording to OSHA Standards 29 (1910.134), there are two fit testing

Gap 2 Sat3 Gap 3 Sat4 Gap 4 Ave gap

�1.06 3.06 �0.75 3.22 �0.59 �0.94�0.39 3.15 �0.41 2.93 �0.64 �0.50�0.34 3.02 �0.34 2.94 �0.42 �0.28�0.58 3.47 �0.16 3.24 �0.40 �0.27�0.07 2.46 �0.40 2.75 �0.10 �0.160.01 2.62 �0.14 2.64 �0.13 �0.080.03 2.59 �0.27 2.78 �0.08 �0.070.19 2.94 0.11 3.01 0.18 0.150.13 2.73 0.14 2.65 0.06 0.150.56 2.59 0.18 2.87 0.46 0.410.66 3.00 0.35 2.93 0.28 0.451.05 2.87 0.46 2.48 0.07 0.50

Table 3Fit test results for current respirators.

OSHA fit test item R1 R2 R3 R4 Grand mean

Mean SD Mean SD Mean SD Mean SD

1. Normal breathing 3.69 0.63 3.06 0.73 3.47 0.59 3.24 0.60 3.372. Deep breathing 3.63 0.64 3.55 0.51 3.49 0.59 3.53 0.59 3.553. Turning side to side 3.09 0.64 3.22 0.52 3.81 0.82 3.55 0.65 3.424. Moving head up and down 3.55 0.65 3.46 0.51 3.52 0.59 3.53 0.65 3.525. Talking 3.65 0.76 3.88 0.67 3.81 0.50 3.21 0.71 3.646. Bending over 3.49 0.51 3.69 0.75 3.72 0.54 3.18 0.69 3.527. Normal breathing 3.67 0.48 3.22 0.41 3.34 0.48 2.99 0.58 3.31

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procedures of respiratory protective equipment: (1) Qualitative FitTest (QLFT) and (2) Quantitative Fit Test (QNFT) (OccupationalSafety and Health Administration, 2004). The qualitative fittesting involves using gas, vapor, or aerosol test agent into an areaaround the head of the respirator user. It is then determinedwhether the respirator user can detect the presence of the testagent through means such as odor, taste, or nasal irritation. If theuser detects the presence of the test agent then the respirator fit isconsidered to be inadequate.

The quantitative test entails numerical evaluation by measuringthe amount of leakage into the respirator. This testing can be doneby generating a test aerosol as a test atmosphere, using ambientaerosol as the test agent, or using controlled negative pressure(CNP) to measure the volumetric leak rate. Appropriate instru-mentation is required to quantify respirator fit (Occupational Safetyand Health Administration, 2004).

In this study, an adaptation of the qualitative fit test was used toassess the fit of the respirator based on the general requirementsproposed by OSHA (Occupational Safety and Health Administration,2004). The test considered position of the respirator on the nose,room for eye protection, room to talk, and position of respirator onface and cheeks.

The succeeding exercises summarize the fit testing methodswhich must be performed as described in the OSHA standards(Occupational Safety and Health Administration, 2004).

1. Normal breathing. In a normal standing position, without talk-ing, the subject shall breathe normally.

Fig. 2. Critical facial dimensions for res

2. Deep breathing. In a normal standing position, the subject shallbreathe slowly and deeply, taking caution so as not tohyperventilate.

3. Turning head side to side. Standing in place, the subject shallslowly turn his/her head from side to side between the extremepositions on each side. The head shall be held at each extrememomentarily so the subject can inhale at each side.

4. Moving head up and down. Standing in place, the subject shallslowly move his/her head up and down. The subject shall beinstructed to inhale in the up position (i.e., when looking towardthe ceiling).

5. Talking. The subject shall talk out loud slowly and loud enoughso as to be heard clearly by the test conductor. The subject readfrom a prepared text.

6. Bending over. The test subject shall bend at the waist as if he/shewere to touch his/her toes. Jogging in place can be done whenthe fit test enclosure doesn’t permit bending at the waist.

7. Normal breathing. Same as exercise (1).

Each worker tested the four respirators. Using the exercisesabove, the workers were asked to rate their experience (1 e

dissatisfied and 5 e most satisfied).The fit test result for the four respirators is shown in Table 3. In

terms of breathing exercise, the first respirator has the highestcomfort rating. However, when the workers were subjected tomovement, the breathing behavior changed across time. Respirator3 resulted to better resistance with movement, while respirator 2had highest score in the reading/ talking exercise.

pirator design from Farkas (1981).

Table 4Relevant facial dimensions measured.

Definition Landmark points 5th percentile 95th percentile

Front view Side of bridge to deepest point of bridge of nose mf-se-mf 1.00* 1.40Bridge of nose to bottom of chin se-gn 8.98* 10.86Most lateral side of nose to opposite side al-al 4.20 4.75*Most lateral angle of jaw to opposite side (passing in front) go-go 11.00* 11.88Most lateral angle of jaw to lowest point of the chin go-gn 5.50* 5.94

Side view The highest elevated point on the cheek area to highest point on the other side dt-dt 6.00* 6.88Nose protrusion se-prn 0.97 1.54a

Most lateral angle of jaw to opposite side (passing at the back) go-go 70.00 85.00a

Most lateral curve at the side of the nose to ac-op 65.00 80.00a

Vertical distance from back of head to vertex op-v (vertical) 9.50 9.60a

Horizontal distance from back of head to vertex op-v (horizontal) 9.11 9.48a

a Percentile to be used in the design.

A.M.J.A. Gutierrez et al. / International Journal of Industrial Ergonomics 44 (2014) 131e139 135

Based on the evaluations done for the four respirators, thefollowing attributes need attention in terms of design: odorfiltration, strap adjustment, contour of face piece, and skincomfort.

3. Prototype design and evaluation

In designing the prototype respirator, several decisions need tobe made related to material and mask contour. The succeedingsections discuss the alternatives considered and the final decisionsmade about the relevant issues about the design.

3.1. Face piece material selection

Using the right material for the respirator can enhance the skincomfort of the users and seal the nose from odors coming from theenvironment. For the prototype, a choice was made between nat-ural rubber and silicone. Silicone was selected due to its goodresistance to extreme temperature and flexibility. It also works wellin products such as respirators because it is odorless and has goodsealing property. Rubber has a strong odor that users may findannoying while being used.

Fig. 3. Narrow

3.2. Strap material selection

The straps of the respirator must be made of a stretchable ma-terial. The elastic strap will serve as adjustment mechanisms toaccommodate the difference in measurements of the auto painters.This means that the elastic band’s soft shape will be able to moldwith the shape of the user’s head/skull.

3.3. Face piece contour design

Identification of proper facial landmarks to use and getting theright dimensions are critical in designing the proper contour of theface piece. The dimensions of the new respirator were based on thelandmark points proposed by Farkas (1981) as illustrated in Fig. 2.Actual measurements of these facial dimensions were taken fromthe 85 participants who are employees of the company. Formeasuring facial anthropometry, the method employed by Zhuangand Bradtmiller (2005) was followed. In this method landmarks onthe face of the participants were marked using an eyebrow pencil.Distances between landmarks were then measured using ameasuring tape. The mean and standard deviation of relevantanthropometric datawere computed to determine the 5th and 95th

design.

Fig. 4. Triangular design.

A.M.J.A. Gutierrez et al. / International Journal of Industrial Ergonomics 44 (2014) 131e139136

percentile values that were used in designing the prototype. Table 4shows all facial dimensions measured and the corresponding per-centiles computed. Values with asterisks represent the percentileused in the design.

Two contour design alternatives were developed based on faciallandmarks indicated in Fig. 3. The first contour design used themost lateral side of the nose (al-al) as basis for shape of the upperpart of the mask. Thus, it is narrow at the top and widens at thebottom to cover the mouth and the cheeks. The pressure points areconcentrated on the nose, mouth, and cheeks area as seen in Fig. 4.This design provides a thinner look on the face and will seal theodor from the sides of the nose. The shape of the mask was derivedby first drawing the mask with measurements based on facialanthropometric data. The dotted lines in Fig. 3 were used as basis ofthe shape. The rough edges were smoothed using a drawing soft-ware until the final contour was obtained.

Another alternative considered is the Triangular Design wherethe basis of the shape had been the highest elevated point on thecheek area from both sides (dt-dt). This alternative covers a sig-nificant portion of the face and provides a wider look of the mask.However, it can seal the odors very well by the material coming incontact with the cheeks. Similar to the narrow design, the contourwas derived from facial anthropometric data obtained from thepainters.

Initial prototypes of the two designs were made using Styro-foam material for testing. The rough prototypes of the masks weregenerated and used by the painters for a fewminutes of evaluation.Fit testing was done according to the protocol proposed by OSHA(2004). Based on the ratings obtained from the fit-test, the nar-row design emerged with the highest score and was chosen to beused for the final prototype.

Fig. 5. Kimberly clark support design.

3.4. Strap design

Several variations of the strap were considered based on thestrap design patented by Kimberly Clark as seen in Fig. 5. This

design holds the mask in place and the width of the strap providesstability. The only problem with this design is the lack of flexibilityin terms of adjustment.

Using the Kimberly Clark as design inspiration, three alterna-tives were generated for the respirator strap: single band, doubleband, and headband as shown in Fig. 6.

The headband design is an adaptation of the Kimberly Clark sidesupport strap design except that the material is made of garter thatis of a higher grade of material to prevent it from easily wearing andtearing. Since garter is an elastic material no adjustment mecha-nisms were included. This design will secure the face piece of theuser while providing ease of putting it on.

The double band design provides better support respirator suchthat the user will not feel the weight of the cartridges very much.

Fig. 6. Strap design alternatives.

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The two straps will have adjustablemechanisms as well as the strapitself being of stretchable quality.

The headband design is an improved version of the double banddesign. It provides a snugger fit and distributed the load of thecartridge to different areas of the head. As such, it will providegreater comfort to the user and allow them to use the respirator forlong periods of time.

Each of these straps was fitted to the narrow design face pieceand evaluated using the fit-testing protocol of OSHA (2004). Theresult of the fit test for straps is shown in Table 5. The headbanddesign showed best performance in almost all aspects of the fit test.It provided more stability and better fit compared to the first twostrap designs.

4. Final prototype design and testing

The final prototype respirator has two major parts, namely: thecenter part and the contour part. The center part holds the cartridgeof the respirator. Since the cartridge alone weighs 1.5 pounds, thecenter cannot be fabricated using the same type of material as thecontour part. In order to support the weight of the cartridge, it willbe made of organic resin, which is strong enough to prevent sag-ging of the cartridge. Fig. 7 shows the design of the prototyperespirator. Different views are shown for better understanding ofthe design.

For the contour part, siliconeerubber material (Grade A) wasused since it is softer than ordinary silicone plastic. Grade A in-dicates the softness of the material, which is better in comparisonto other grades available. The material can hold the contour of therespirator as well as conform to the shape of the face of the wearer.

The strap used a combination of plastic and garter. The garterwas used in order to allow adjustments for the respirator whileplastic is used on the corner head part in order to allow maximumsupport. Double straps were used for better support. Support was

Table 5Fit test results for straps evaluated.

Fit test

Normal breathing. In a normal standing position,without talking, the subject shall breathe normally.

Deep breathing. In a normal standing position, the subjectshall breathe slowly and deeply, taking caution so as not to hyperventilate.

Turning head side to side. The head shall be held at each extreme momentarilyso the subject can inhale at each side.

Moving head up and down. Standing in place, the subject shall slowly move his/herhead up and down. (When looking toward the ceiling).

The subject shall talk out loud slowly and loud enough so as to be heard clearly by thtest conductor. The subject can read from a prepared text such as the Rainbow Passcount backward from 100, or recite a memorized poem or song.

Bending over. The test subject shall bend at the waist as if he/she were to touch his/hNormal breathing. Same as exercise (1)Average score

provided from the top corner of the head as well as below the skullor cerebra. This indicates appropriate pressure hold on the headand enables even distribution of the weight of the respirator acrossthe head.

The flap design used was adapted from the design of Japuntichflap. This design has an inward fold at the same time it has a liningof cushion that is made of silicone. The lining of silicone will restalong the nose, cheeks and chin area of the wearer. The softness ofthe silicone material assures the comfort of the users.

The prototype weighs 2.34 lbs. The single cartridge respirator ismuch lighter as compared to the double cartridge respirators(respirators 1 and 2). The horizontal and vertical measurements are11.5 cm and 12 cm, respectively, while the depth is 7.5 cm. The strapis longer than the other 4 respirators at 120 cm. This will enable theusers to make adequate adjustments. The horizontal and verticaldimensions were based on the most lateral angle of jaw to oppositeside (passing in front) and bridge of nose to bottom of chin,respectively.

After manufacturing the prototype, it was tested in the actualenvironment. All 85 auto painters were given a chance to use theprototype for 2 h because according to Liard (2002) discomfortstarts to set-in after this amount of time. Satisfaction ratings wereobtained from the survey questionnaire. Based on the resultsshown in Table 6, there is high satisfaction rate in all tested attri-butes of the prototype respirator except for the weight because it isheavier than respirators 3 and 4. The heavy weight is due to thecartridge used in the prototype which weighs 1.5 lbs. T-test ofmeans between current and prototype respirators showed thatthere is significant mean satisfaction difference in favor of theprototype respirator for all attributes.

Fit test was conducted by asking the painters to use the proto-type respirator in the actual working environment. First they wereasked if they can detect the paint odor in the surroundings. They allresponded negatively so they were then asked to do a series of

Single band Double band Head band

4.54 4.65 4.60

3.74 3.88 3.99

3.32 3.15 3.62

3.09 3.50 3.67

eage,

3.79 3.90 4.01

er toes. 3.23 3.57 3.994.43 4.40 4.773.73 3.86 4.09

Fig. 7. Respirator design.

Table 7Mean and standard deviation of prototype satisfaction rating from fit test.

Fit test exercise Prototype

Mean SD

Normal breathing in a normal standing position without talking 3.93 0.40Deep breathing in a normal standing position, breathing

slowly and deeply, taking precaution not to hyperventilate3.72 0.46

Turning the head slowly from side to side, while standingin place, with the employee holding his/her headmomentarily at each extreme so that the employeecan inhale at each side

3.76 0.52

Moving the head up and down slowly while standing inplace inhaling in the up position when lookingtoward the ceiling

3.82 0.55

Talking out loud slowly reading from prepared text suchas the rainbow passage, counting backward from 100,or reciting a memorized poem or song

4.13 0.53

Bending at the waist as if to touch toes (jogging in placecan be done when the fit test enclosure doesn’t permitbending at the waist)

3.95 0.45

Normal breathing (as described above) 3.95 0.61

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activities. After these activities, theywere asked to rate (5¼ highestand 1¼ lowest) each of the exercise performed as part of the test.Each exercise must be performed for 1 min, except for the grimaceexercise which must be performed for 15 s. The respirator must notbe adjusted once the fit test exercises begin. Any adjustment voidsthe test, and the fit test must be repeated.

Table 7 shows the rating obtained from the fit testing of theprototype respirator. The ratings obtained were compared with thecurrent respirator fit test shown in Table 3. T-test of means wasconducted to determine if there is a significant difference in themean satisfaction rating. Table 8 shows that the prototype is betterin almost all aspects except in deep breathing. Its performance inthe fit test is much better than respirator 1 in all aspects. Theprototype is especially better in the aspect of normal breathing andtalking. Workers were able to move and talk freely using the newrespirator. The result shows that the contour principle applied inthis study was able to improve the fit of the new respirator to thesatisfaction of the users.

Table 6Comparison of satisfaction ratings of current and prototype respirators.

Attribute Satisfaction rating

R1 R2 R3 R4 Prototype

Ease of breathing 3.69** 3.06** 3.47** 3.24** 4.08Ease of communication 2.84** 2.98** 2.59** 2.87** 4.14Skin comfort 2.80** 2.79** 2.46** 2.75** 3.66Weight of the respirator 2.87** 3.46** 2.48 2.35 2.46In-respirator temperature 2.87* 2.72** 2.73** 2.65** 3.18In-respirator humidity 2.89** 2.88** 2.59** 2.78** 3.59In-respirator odor circulation 2.95** 3.02** 2.94** 3.01** 3.62Filtration of odor from substances 2.45** 2.75** 3.06** 3.22** 3.53Filtration of particles

from substances3.37** 3.02** 3.02** 2.94** 3.91

Strap adjustments 3.01** 3.18 3.15 2.93** 3.38Contour of facepiece 2.71** 2.78** 2.62** 2.64** 3.64Visual range 3.17** 3.31 3.00** 2.93** 3.36

*p< 0.05, and **p< 0.01.

5. Discussion

The main difference of the prototype respirator from the regularrespirator available in the local market is measurement that wasderived from actual users. The prototype respirator also made useof silicone, which is softer and more comfortable. Only the Respi-rator 1 is made of silicone among the four respirators evaluated inthis study. The design also used single cartridge rather than doublecartridge in order to make it lighter. However, the cartridge used inthe prototype is already heavy and can still be improved. This is theonly attribute that was evaluated negatively by the users. Futuredesigns can consider a different type of filter that is lighter to placein the cartridge.

This study was able to address the challenges that are related tothe use of respirators in the industry such as skin comfort, odorfiltration, and right fitting. The issue of skin comfort was addressedby using silicone rubber. This material reduced itchiness, irritationandmarks on the face while worn by the workers. Filtration of odorfrom substances was not tackled since there is only one generictype of cartridge used by the market on auto-painting jobs. How-ever, the ability of the respirator to lock the surface of the skin toprevent external fumes was addressed. The contour developedbased on the facial anthropometry of the users was able to lock thespaces along the side of the face. The acceptability of the prototypehas been investigated and validated using the fit test, and showedthat it fits well to the users.

In relation to fitting, the strap of the prototype was also made tobe highly adjustable to the type of fit desired by the workers. Thedesign is highly stable and provides adequate support to the maskdespite of its heaviness.

Table 8Comparison of fit test rating of current and prototype respirators.

OSHA fit test item R1 vs.Proto

R2 vs.Proto

R3 vs.Proto

R4 vs.Proto

1. Normal breathing * ** ** **2. Deep breathing3. Turning side to side ** **4. Moving head up and down * *5. Talking ** * **6. Bending over ** **7. Normal breathing * ** ** **

*p< 0.05, and **p< 0.01.

A.M.J.A. Gutierrez et al. / International Journal of Industrial Ergonomics 44 (2014) 131e139 139

6. Conclusion

The prototype respirator was able to address the needs of theauto painters in relation to skin comfort, odor filtration and fitting.The use of silicone rubber provided softness in the skin and pre-vented itchiness, irritation and marks on the face of the workers.Odorwas filtered using a single cartridge and the facewas insulatedwell using a contour that considered facial landmarks andanthropometry of the workers.

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