Respirator Donning in Post-Hurricane New Orleans

Most participants did not properly don an N95 FF respirator


M any respirators certifi ed by the National Institute for
Occupational Safety and Health (NIOSH), particularly disposable N95 fi ltering facepiece respirators (N95 FF respirators [ Figure 1]), are available to the public. The certifi cation indicates that the respirator material will perform at a given fi lter effi ciency (1). Because proper fi t is also necessary for respirator function, US regulations state that an employer who requires workers to wear respirators must establish a respiratory protection program that covers respirator selection and maintenance, fi t testing, and worker instruction (2). Although nonoccupational respirator use has not been well studied, members of the public who use respirators may be less likely than workers in a respiratory protection program to achieve a proper fi t, given lack of formal training (3).
Public health agencies have recommended N95 FF respirators to members of the public for some situations. Such occasions have included after major fl oods, for potential heavy exposure to bioaerosols in water-damaged buildings (Grand Forks, North Dakota, 1997; eastern North Carolina after Hurricane Floyd, 1999) (4), and for settings that pose a risk for airborne transmission of infection, such as during the severe acute respiratory syndrome (SARS) epidemic (for select patients at risk of acquiring the infection and for persons visiting patients with SARS) (5)(6)(7). There is also a longstanding recommendation for N95 FF respirator use for visitors of hospitalized patients with tuberculosis (8). The US Department of Health and Human Services (HHS) currently recommends that persons living in or visiting an area affected by avian infl uenza A (H5N1) wear N95 FF respirators when in contact with birds in an enclosed environment (9).
In the fall of 2005, after the unprecedented fl ooding in New Orleans, Louisiana caused by Hurricanes Katrina and Rita, public health offi cials recommended that members of the public use N95 FF respirators when cleaning or remediating mold-contaminated buildings (10). A survey of 159 New Orleans area residents 7 weeks after Katrina found that 68% of those interviewed were aware of the recommendation (11) and that at least 30% of those participating in remediation activities had used a NIOSH-certifi ed respirator (12). Despite these levels of awareness and experience, subsequent anecdotal reports suggested that some New Orleans residents were not properly donning N95 FF respirators. Improper donning would promote the entry of unfi ltered air through leaks or gaps between the respirator and the skin, compromising the protection offered (13). To better understand respirator use by the public, we investigated the nonoccupational use and donning of N95 FF respirators in post-hurricane New Orleans.

Participants
Using geographic information system mapping software, we randomly selected homes in Orleans Parish (city of New Orleans). To focus on residential areas, we eliminated 6,345 of the parish's 10,181 census blocks (US Census, 2000). The eliminated blocks were likely to be sparsely populated or to contain industrial buildings, commercial centers, or parks (blocks with <20 housing units and blocks in the lower 2.5% of housing unit density); to contain mostly high-rise apartment buildings or public housing units that would be diffi cult to access or remain uninhabited (blocks in the upper 2.5% of housing unit density); and to be in uninhabited neighborhoods (blocks in the Lower Ninth Ward). We randomly generated 600 waypoints (unique locations based on latitude and longitude) across the remaining 3,836 census blocks.
Each waypoint served as a starting point to locate eligible participants. Using a global positioning system device, a survey team navigated to a waypoint and identifi ed the nearest home. To be eligible for participation, a person had to be an English-speaking adult (>18 years of age) associated with a home as its owner, current occupant, or relative/friend of the owner/occupant. Because we were interested in nonoccupational respirator use by the general public, persons at a home as paid employees (e.g., remediators) were not eligible. However, residents encountered at their own homes who were employed as remediators were not excluded. If unable to conduct an interview at the fi rst encountered home, the team proceeded in a systematic fashion to the next home. Once 1 interview was conducted at a waypoint, the team navigated to the next waypoint and repeated the process.

Questionnaire and Evaluation of Respirator Donning
From March 4 to March 11, 2006, survey team members interviewed participants with a 10-minute questionnaire that collected information on experience with residential fl ooding, water damage, and mold growth; participation in mold clean-up activities; lifetime and post-Katrina experiences with respiratory protection (both noncertifi ed dust masks and surgical masks, hereafter "masks"; and NIOSH-certifi ed respirators, including disposable and reusable types, hereafter "certifi ed respirators"); and nonidentifying demographic factors, including self-identifi ed ethnicity and race. Each team used the same photographs and actual examples of masks and certifi ed respirators during the interviews.
Each interview included an evaluation of respirator donning. Interviewers were trained before the survey on proper donning (Figure 2), including the following: proper orientation of the respirator; use of both straps; proper placement of straps; need for tightening of the nose clip; and need for removal of facial hair (14,15). A participant with an N95 FF respirator that appeared to be in good condition was permitted to use this respirator for the evaluation. Otherwise, the participant was asked to choose between 2 models then available from New Orleans retailers. The interviewer asked the participant to put on the N95 FF respirator as he or she would for participating in mold clean-up activities. Written and pictorial manufacturer's instructions were included with the respirator packaging, but no additional instructions were given until the evaluation was complete (16). The interviewer recorded whether the participant referred to the manufacturer's instructions . The disposable N95 fi ltering facepiece respirators pictured on the right (with exhalation valve, upper right; without exhalation valve, lower right) are made of material certifi ed by NIOSH to fi lter 95% of 0.3-μm diameter particles and bear the NIOSH name and "N95" fi lter identifi cation. The European FFP2 respirator is most analogous to the N95 fi ltering facepiece respirator. NIOSH also certifi es more expensive reusable respirators (not pictured), which can be fi tted with disposable cartridges that fi lter particles. Reusable respirators may cover the face from the bridge of the nose to the chin (half-face) or from the forehead to the chin (full-face). and, once the participant indicated that the respirator was donned, noted any observed "donning errors" that could contribute to an insuffi cient fi t.

Statistical Analyses
For calculations of frequencies of donning errors, we included all participants who had at least 1 error. However, because 2 errors, visible gap and facial hair, could refl ect aspects of study design (size and shape of respirators offered and lack of opportunity to shave before evaluation, respectively) rather than participants' donning technique, they were not considered in analyses of factors associated with proper donning. For these analyses, participants with at least 1 of the other donning errors were categorized as improperly donning the respirator; the remaining participants were categorized as properly donning the respirator.
To identify factors associated with proper donning, we used contingency tables and simple logistic regression. We included signifi cant factors (p<0.05) in multiple logistic regression models, applying stepwise logistic regression. We used the likelihood ratio χ 2 test and calculated odds ratios (OR) with 95% likelihood confi dence intervals (CI).

Participants
We conducted 553 interviews at the 600 visited waypoints, for a response rate of 92%. Half of the participants were male, with a median age of 50 years, and about half identifi ed their race as Caucasian and half as African-American or black (Table 1). Most described previously using a mask or respirator, but few reported ever having a respirator fi t test. Most had participated in mold clean-up activities since Hurricane Katrina.

Respiratory Protection Use during Mold Clean-up Activities
Overall, of the 553 participants interviewed, 42% (n = 233) had used a certifi ed respirator, and 35% (n = 192) had used an N95 FF respirator, specifi cally, for mold clean-up activities since Katrina. Among the 368 who reported participating in mold clean-up activities, most (n = 315, 86%) reported using a mask or certifi ed respirator during those activities, most frequently the N95 FF respirator ( Table 2). A minority (n = 60, 19%) of the 315 reported referring to the manufacturer's instructions. More commonly (n = 129, 41%), participants stated that they used respiratory protection without any instruction.

Evaluation of Respirator Donning
A total of 538 (97%) participants agreed to put on an N95 FF respirator. Most of these (n = 489, 91%) used 1 of the 2 models offered by the interviewers. Twelve (2%) referred to the manufacturer's directions.
Overall, 433 (80%) of the participants who donned an N95 FF respirator were noted to have at least 1 donning error that could contribute to a poor fi t. More than half of these did not tighten the nose clip, and half incorrectly placed the 2 straps; in addition, 22% put the respirator on upside down, and 21% used only 1 strap (Table 3). While 31% (n = 135) made l error, 34% (n = 146) made 2, and 35% (n = 152) made >3.

Characteristics Associated with Proper Donning
For 24 participants, the only noted donning error was a visible gap (n = 6) or facial hair (n = 18). When these 24 persons who otherwise demonstrated proper donning were included, 129 (24%) of the participants properly donned the N95 FF respirator. In simple logistic regression analyses of all participants, proper donning was signifi cantly associated with several personal factors: being male, being Caucasian, and being a nonrenter (i.e., a homeowner or as- sociate) in the home at which the interview occurred. In addition, proper donning was associated with post-hurricane experiences: having been inside a water-damaged or moldy home and having participated in mold clean-up. Finally, proper donning was associated with several factors related to respirators: ever having used a mask or certifi ed respirator, ever having had a respirator fi t test, having at the time of the interview a mask or certifi ed respirator, and having at the time of the interview a respirator confi rmed by the interviewer to be NIOSH certifi ed (Table 4).
For the subset that had participated in clean-up activities, proper donning was also associated with use of respiratory protection during clean-up, including having specifi cally used an N95 FF respirator. For the subset that had used a mask or certifi ed respirator during clean-up, having obtained that mask or respirator from the workplace and having obtained information on how to use the mask or respirator from the workplace were also signifi cant factors. Proper donning was not associated with age, Hispanic ethnicity, level of fl oodwater, water incursion due to roof or window damage, extent of mold coverage, current employment in mold remediation, asthma diagnosis, smoking status, or respirator brand.
When multiple logistic regression was used, the factors signifi cantly associated with proper donning for all participants  (12)  *Data for some characteristics were missing for some participants. †Participants could select >1 racial category; total >100%. ‡Home at which participant was encountered and interviewed. §"Fit test" was defined in the questionnaire as "a test in which a technician measures how well the respirator fits your face during activities such as talking and moving your head. It could involve smelling smoke, tasting something sweet or bitter, or a special machine that counts particles." . These same factors were also signifi cant for the subset that used a mask or certifi ed respirator during clean-up.

Discussion
The protection afforded by a certifi ed respirator depends on its fi t, and a fundamental component of achieving a good fi t is proper donning (13,17). In post-hurricane New Orleans, public concern about adverse health effects of exposure to mold was near universal (11,12). Yet our investigation demonstrated that, despite this high level of motivation, most of participants did not properly don an N95 FF respirator.
Our investigation benefi ted from several strengths. We used a random selection process to obtain our sample, and comparisons with existing population-based surveys suggest we achieved a representative cross-section (18,19). Given inconsistencies in respiratory protection terminology, we facilitated effective communication by using photographs and actual examples of masks and certifi ed respirators. Finally, of the few prior fi eld investigations that have addressed N95 FF respirator donning (20)(21)(22), none have focused on nonoccupational use. †Among those participants with only 1 observed donning error, 6 had a visible gap between the respirator and skin, and 18 had facial hair. These 24 participants are included in calculations of frequencies of donning errors. For analyses of factors associated with proper donning, they were considered to have properly donned the respirator.
‡The "other" category was used for 2 participants who were noted to be unable to put on the respirator and for 1 participant who did not use either of the 2 straps. For 2 other participants, the "other" category was indicated, but the interviewer did not further specify the nature of the errors. *Proportion of participants with characteristic demonstrating proper donning, followed by proportion of participants without characteristic demonstrating proper donning. For the first characteristic, 34% of males and 12% of females properly donned the respirator. †Unadjusted odds ratio (OR) and 95% confidence interval (CI) for proper donning of disposable N95 FF respirator by participants with characteristic compared to participants without characteristic. ‡538 of 553 participants donned an N95 FF respirator for the interviewer. For some analyses, N is <538 (as noted) because of missing data. §The following variables were also statistically significant in simple logistic regression analyses for this subset: male, Caucasian, ever used mask or respirator, ever had respirator fit test, had mask or respirator at time of interview, and had certified respirator at time of interview.
¶367 of 372 who participated in clean-up donned an N95 FF respirator for the interviewer. N is <367 because of missing data. #The following variables were also statistically significant in simple logistic regression analyses for this subset: male, Caucasian, ever had respirator fit test, had mask or respirator at time of interview, had certified respirator at time of interview, used certified respirator during clean-up, and used disposable N95 FF respirator during clean-up. **312 of 315 who used a mask or respirator during clean-up donned an N95 FF respirator for the interviewer.
An important limitation is that we did not confi rm the observed proper donnings with respirator fi t testing. While we cannot estimate the relative contribution of each donning error to declining protection without quantitative measurements, those participants who put on the respirator improperly would clearly have failed a standard fi t test. However, the outcome in those who appeared to properly put on the respirator is less certain because even a properly donned respirator may have leaks that limit its effectiveness. A study of 18 different N95 FF respirator models found that, overall, in the absence of fi t testing, 74% of proper donnings would provide the full protection possible with an N95 FF respirator (range 31%-99%, depending on the model) (23). Thus, the proportion of our participants who would have achieved the full protection possible with an N95 FF respirator is likely to be lower than the proportion who demonstrated proper donning. Ultimately, designing models with good fi t characteristics would be benefi cial.
Our fi ndings have implications for the use of N95 FF respirators by members of the public to prevent the transmission of communicable diseases. Both experimental and epidemiologic studies suggest that airborne transmission of infl uenza (by small particles <10 μm) can occur and may result in more severe disease than transmission by large droplets or fomites (24)(25)(26)(27). A recent review argues that airborne transmission may play an important role in the spread of a pandemic strain (28). While formal recommendations for N95 FF respirator use by the public do not exist-beyond the HHS recommendation regarding potential exposures to infected birds-a recent Institute of Medicine (IOM) report notes that "a properly fi tted N95 FF respirator is likely to be both the least expensive and the most widely available NIOSH-certifi ed respirator for protecting... the public against airborne [infl uenza] infection" (29). Our results suggest that much of the public may have diffi culty achieving a proper fi t because of improper donning. Given the observed role of experience in proper donning, and the high frequency of recent experience with respirators reported by our survey participants, one could argue that the overall performance in post-Katrina New Orleans is likely to be superior to that of virtually any other locale.
The World Health Organization anticipates use of respiratory protection by the public will occur spontaneously in the event of pandemic infl uenza (30,31). Indeed, N95 FF respirators are currently being marketed to the public as "bird fl u masks" (32). While uncertainty remains about the level of protection needed against infl uenza and that offered by an N95 FF respirator, an improperly donned N95 FF respirator will provide less protection than a properly donned one. Our results suggesting that workplace training increased proper donning among the public indicate that educational efforts could have a positive effect. Since few of our participants reported, or were observed, referring to manufacturers' instructions, consideration also should be given to incorporating instructions onto the respirator itself, such as arrows or simple words ("nose," "chin") to indicate orientation. The IOM report's authors could fi nd no simple modifi cation of N95 FF respirators that would prevent the need for fi t testing (29). Short of mass fi t testing, proper donning will be the vital step to ensuring that members of the public using N95 FF respirators derive the greatest possible benefi t from them.
Even under workplace conditions, respirator donning may be imperfect. An observational study of 62 healthcare workers in 3 California hospitals found that 40 (65%) improperly put on N95 FF respirators before entering the room of a patient in isolation for tuberculosis. Errors included use of only 1 strap, incorrectly placed straps, and presence of facial hair (21). The results of that study, in terms of the proportion who demonstrated improper donning and the nature of the errors, are similar to our fi ndings. The impact of the 2005 US policy that suspended enforcement of annual fi t testing of healthcare workers who use respirators for occupational exposure to tuberculosis is unknown (33). Yet N95 FF respirators will clearly be part of healthcare workers' defense in the event of pandemic infl uenza (34,35). HHS, as part of procurement of essential medical supplies for pandemic infl uenza, has stockpiled 20 million N95 FF respirators and plans to acquire 87 million more through September 2007 (36). The pandemic plans of other countries, including Australia and France, recommend use of N95 (or FFP2) respirators (28). Further evaluation of respirator donning among healthcare workers therefore may be warranted.
In summary, this population-based survey of nonoccupational respirator use found that a minority of participants demonstrated proper donning of an N95 FF respirator. Our fi ndings are of particular importance to public health agencies planning for future events, from fl oods to pandemic infl uenza, in which use of N95 FF respirators by the public will be recommended or is anticipated. A unique opportunity exists to enhance protection of the public through interventions, such as educational campaigns, training sessions, and respirator design modifi cations, aimed at improving the public's ability to don a respirator correctly. Infection control offi cers and the healthcare workers they protect also may benefi t from the insights gained from this survey. data acquisition; Hannah Alsdurf, Michael Beaty, Brent C. Doney, Matthew Duling, Monica C. Graziani, Mark F. Greskevitch, Todd C. Noletto, Amy M. Nuernberg, David L. Spainhour, James E. Taylor, Brian D. Tift, and Snigdha Vallabhaneni for their roles in data acquisition; and Gerald R. Hobbs for his contribution to data analysis.