Knowledge, attitudes and practices regarding respirable silica exposure and personal protective equipment use among brick kiln workers in Nepal.

OBJECTIVES: Brick kiln workers in Nepal are a neglected population who are exposed to high respirable silica concentrations, and few use interventions to reduce exposure. We aimed to characterise the prevalence of respiratory personal protective equipment (PPE) use, understand knowledge and attitudes towards kiln dust and respiratory PPE and identify factors associated with respiratory PPE use. METHODS: We conducted a cross-sectional study in Bhaktapur, Nepal. We used simple random selection to identify 10 out of 64 total kilns and stratified random sampling of 30 households to enrol workers aged ≥14 years within selected kilns. Field workers surveyed participants using structured questionnaires. Our primary outcome was to characterise the prevalence of current respiratory PPE use and secondary outcomes were summaries of knowledge, attitudes and practice of PPE use. RESULTS: We surveyed 83 workers (mean age 30.8 years, 77.1% male). Of these, 28.9% reported current respiratory PPE use at work, 3.6% heard of silicosis prior to the survey and 24.1% correctly identified the best respiratory PPE (N95, compared with surgical masks and barrier face coverings) for reducing dust exposure. Respiratory PPE users had higher income (mean monthly household income US$206 vs US$145; p=0.04) and education levels (25% vs 5.1% completed more than primary school; p=0.02) compared with non-users. CONCLUSIONS: Respiratory PPE use was low. Workers had poor knowledge of kiln dust health effects and proper respiratory PPE. We highlight important barriers to PPE use, particularly knowledge gaps, which can guide future investigations to reduce the silicosis burden among brick kiln workers.

Face masks considerably reduce COVID-19 cases in Germany.

We use the synthetic control method to analyze the effect of face masks on the spread of COVID-19 in Germany. Our identification approach exploits regional variation in the point in time when wearing of face masks became mandatory in public transport and shops. Depending on the region we consider, we find that face masks reduced the number of newly registered severe acute respiratory syndrome coronavirus 2 infections between 15% and 75% over a period of 20 days after their mandatory introduction. Assessing the credibility of the various estimates, we conclude that face masks reduce the daily growth rate of reported infections by around 47%.

Identifying airborne transmission as the dominant route for the spread of COVID-19.

Various mitigation measures have been implemented to fight the coronavirus disease 2019 (COVID-19) pandemic, including widely adopted social distancing and mandated face covering. However, assessing the effectiveness of those intervention practices hinges on the understanding of virus transmission, which remains uncertain. Here we show that airborne transmission is highly virulent and represents the dominant route to spread the disease. By analyzing the trend and mitigation measures in Wuhan, China, Italy, and New York City, from January 23 to May 9, 2020, we illustrate that the impacts of mitigation measures are discernable from the trends of the pandemic. Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the pandemic trends in the three epicenters. This protective measure alone significantly reduced the number of infections, that is, by over 78,000 in Italy from April 6 to May 9 and over 66,000 in New York City from April 17 to May 9. Other mitigation measures, such as social distancing implemented in the United States, are insufficient by themselves in protecting the public. We conclude that wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic. Our work also highlights the fact that sound science is essential in decision-making for the current and future public health pandemics.

The protective effect of tight-fitting powered air-purifying respirators during chest compressions.

BACKGROUND: Airborne personal protective equipment is required for healthcare workers when performing aerosol-generating procedures on patients with infectious diseases. Chest compressions, one of the main components of cardiopulmonary resuscitation, require intense and dynamic movements of the upper body. We aimed to investigate the protective effect of tight-fitting powered air-purifying respirators (PAPRs) during chest compressions. METHODS: This single-center simulation study was performed from February 2021 to March 2021. The simulated workplace protection factor (SWPF) is the concentration ratio of ambient particles and particles inside the PAPR mask; this value indicates the level of protection provided by a respirator when subjected to a simulated work environment. Participants performed continuous chest compressions three times for 2 min each time, with a 4-min break between each session. We measured the SWPF of the tight-fitting PAPR during chest compression in real-time mode. The primary outcome was the ratio of any failure of protection (SWPF <500) during the chest compression sessions. RESULTS: Fifty-four participants completed the simulation. Overall, 78% (n = 42) of the participants failed (the measured SWPF value was less than 500) at least one of the three sessions of chest compressions. The median value and interquartile range of the SWPF was 4304 (685-16,191). There were no reports of slipping down of the respirator or mechanical failure during chest compressions. CONCLUSIONS: Although the median SWPF value was high during chest compressions, the tight-fitting PAPR did not provide adequate protection.

[Biological risk from SARS-CoV-2 and respiratory protection device for health workers during the first pandemic phase: a scenario that had to be avoided]. / Rischio biologico da SARS-CoV-2 e dispositivi di protezione respiratoria per gli operatori sanitari e assistenziali nella prima fase pandemica: uno scenario che doveva essere evitato.

In Italy, the SARS-CoV-2 pandemic showed the devastating consequences of a widespread biological risk not only for the general population, but also for healthcare workers that diagnose COVID-19 and treat patients. In the set of preventive measures taken to reduce this contagion, a fundamental role in personal protection is played by equipment suitable for preventing the contaminated air inhalation. Despite this severe biological risk during the first epidemic phase, some institutional operating protocols and recommendations have shown limitations and contradictions and, therefore, they must not be repeated. It was observed a widespread inadequate use of respiratory protections, such as surgical masks, which show a low efficacy for health workers; adequate respiratory protective devices are instead rarely used, while their use should have been guaranteed more extensively than it is recommended and noticed, according to the current work hygiene legislation.

The COVID-19 pandemic, personal protective equipment and respirator: A narrative review.

INTRODUCTION: The coronavirus disease 2019 pandemic has touched almost every continent. Personal protective equipment (PPE) is the final line of protection of healthcare workers (HCW). There is variation as well as controversy of infection control recommendation with regards to the use of PPE for HCW between institutions. The aim of this narrative review is to of examine and summarise the available evidence to guide recommendation for the safety of HCW. METHOD: A literature search was conducted on the PubMed, MedLine and Embase databases with the keywords "personal protective equipment," "COVID 19," "n95," "health care worker" and "mortality." RESULTS: SARS-nCoV-2 is highly contagious. About 3.5%-20% of HCW has been reported to be infected. The mortality ranges from 0.53% to 1.94%. PPE is part of the measure within a package of prevention and control of pandemic, rather than a replacement of. Respirators are more effective than masks in preventing aerosol transmission to HCWs. Extended use may be considered if guidelines are adhered. Powered air-purifying respirators if available should be used in high-risk procedures. CONCLUSION: Transmission of viruses is multimodal and in the setting of a novel pathogen with high case fatality with no proven effective interventions, PPE that affords the best protection should be available to HCWs.

Relative contributions of transmission routes for COVID-19 among healthcare personnel providing patient care.

The routes of COVID-19 transmission to healthcare personnel from infected patients is the subject of debate, but is critical to the selection of personal protective equipment. The objective of this paper was to explore the contributions of three transmission routes-contact, droplet, and inhalation-to the risk of occupationally acquired COVID-19 infection among healthcare personnel (HCP). The method was quantitative microbial risk assessment, and an exposure model, where possible model parameters were based on data specific to the SARS-CoV-2 virus when available. The key finding was that droplet and inhalation transmission routes predominate over the contact route, contributing 35%, 57%, and 8.2% of the probability of infection, on average, without use of personal protective equipment. On average, 80% of inhalation exposure occurs when HCP are near patients. The relative contribution of droplet and inhalation depends upon the emission of SARS-CoV-2 in respirable particles (<10 µm) through exhaled breath, and inhalation becomes predominant, on average, when emission exceeds five gene copies per min. The predicted concentration of SARS-CoV-2 in the air of the patient room is low (< 1 gene copy per m3 on average), and likely below the limit of quantification for many air sampling methods. The findings demonstrate the value of respiratory protection for HCP, and that field sampling may not be sensitive enough to verify the contribution of SARS-CoV-2 inhalation to the risk of occupationally acquired COVID-19 infection among healthcare personnel. The emission and infectivity of SARS-CoV-2 in respiratory droplets of different sizes is a critical knowledge gap for understanding and controlling COVID-19 transmission.

Rational use of face mask in a tertiary care hospital setting during COVID-19 pandemic: An observational study.

Masks play a role in the protection of health-care workers (HCWs) from acquiring respiratory infections, including coronavirus disease 2019 (COVID-19) in health-care settings. This observational study was conducted among 382 HCWs in a tertiary care setting over a period of 1 month. Descriptive analysis was done to assess the rational and recommended use of masks/respirators during COVID-19 pandemic using a structured observation checklist as a survey tool. A total of 374 HCWs were included, 64.9% of whom were using face masks rationally as mentioned per risk area categorization with a predominance of triple-layered mask during all 4 weeks. Overall, 64.1% used masks correctly. Clear guidelines and strategies can help to increase the compliance of HCWs with rational use of face masks.

Phosphine Exposure Among Emergency Responders - Amarillo, Texas, January 2017.

Phosphine is a highly toxic gas that forms when aluminum phosphide, a restricted-use pesticide* typically used in agricultural settings, reacts with water. Acute exposure can lead to a wide range of respiratory, cardiovascular, and gastrointestinal symptoms, and can be fatal (1). On January 2, 2017, the Texas Department of State Health Services (DSHS) was notified by the Texas Panhandle Poison Center of an acute phosphine exposure incident in Amarillo, Texas. DSHS investigated potential occupational phosphine exposures among the 51 on-scene emergency responders; 40 (78.4%) did not use respiratory protection during response operations. Fifteen (37.5%) of these 40 responders received medical care for symptoms or as a precaution after the incident, and seven (17.5%) reported new or worsening symptoms consistent with phosphine exposure within 24 hours of the incident. Emergency response organizations should ensure that appropriate personal protective equipment (PPE) is used during all incidents when an unknown hazardous substance is suspected. Additional evaluation is needed to identify targeted interventions that increase emergency responder PPE use during this type of incident.

Patterns and predictors of personal protection compliance and workplace hygiene behaviors among workers with elevated blood lead levels in New York State.

Despite increasing awareness and significant progress in reducing lead exposure among workers, elevated blood lead levels (BLLs) continue to be an occupational health problem. Little is currently known about the extent of personal protective equipment (PPE) use among lead-exposed workers. We examined the patterns and predictors of consistent PPE use and workplace hygiene behaviors among workers with elevated BLLs using a survey of 1,459 workers with an occupational lead exposure in New York State (NYS). Routine availability of respirators was commonplace, however only approximately half of workers consistently wore PPE while working with lead. Regular access to showers was reported by 41% of workers, but less than a quarter took showers and subsequently changed into clean clothing before leaving work site. Significant predictors of consistent PPE use and good hygiene behaviors were identified. The findings highlight the need for further educational and policy interventions for lead-exposed employees. Increased employer efforts are also required to provide workplace structures and a culture that supports compliance. These include the provision of routine training and hazard communication, provision of appropriate PPE and hygiene facilities, and enforcing its use where necessary.

Assessment of occupational exposure to asbestos fibers: Contribution of analytical transmission electron microscopy analysis and comparison with phase-contrast microscopy.

From November 2009 to October 2010, the French general directorate for labor organized a large field-study using analytical transmission electron microscopy (ATEM) to characterize occupational exposure to asbestos fibers during work on asbestos containing materials (ACM). The primary objective of this study was to establish a method and to validate the feasibility of using ATEM for the analysis of airborne asbestos of individual filters sampled in various occupational environments. For each sampling event, ATEM data were compared to those obtained by phase-contrast optical microscopy (PCOM), the WHO-recommended reference technique. A total of 265 results were obtained from 29 construction sites where workers were in contact with ACM. Data were sorted depending on the combination of the ACM type and the removal technique. For each "ACM-removal technique" combination, ATEM data were used to compute statistical indicators on short, fine and WHO asbestos fibers. Moreover, exposure was assessed taking into account the use of respiratory protective devices (RPD). As in previous studies, no simple relationship was found between results by PCOM and ATEM counting methods. Some ACM, such as asbestos-containing plasters, generated very high dust levels, and some techniques generated considerable levels of dust whatever the ACM treated. On the basis of these observations, recommendations were made to measure and control the occupational exposure limit. General prevention measures to be taken during work with ACM are also suggested. Finally, it is necessary to continue acquiring knowledge, in particular regarding RPD and the dust levels measured by ATEM for the activities not evaluated during this study.

Exploring respiratory protection practices for prominent hazards in healthcare settings.

The use of respiratory protection, an important component of personal protective equipment (PPE) in healthcare, is dependent on the hazard and environmental conditions in the workplace. This requires the employer and healthcare worker (HCW) to be knowledgeable about potential exposures and their respective protective measures. However, the use of respirators is inconsistent in healthcare settings, potentially putting HCWs at risk for illness or injury. To better understand respirator use, barriers, and influences, the National Institute for Occupational Safety and Health (NIOSH) Health and Safety Practices Survey of Healthcare Workers provided an opportunity to examine self-reported use of respirators and surgical masks for targeted hazards. The hazards of interest included aerosolized medications, antineoplastic drugs, chemical sterilants, high-level disinfectants, influenza-like illness (ILI), and surgical smoke. Of the 10,383 HCWs who reported respiratory protection behaviors, 1,904 (18%) reported wearing a respirator for at least one hazard. Hazard type, job duties, site characteristics, and organizational factors played a greater role in the likelihood of respirator use than individual factors. The proportion of respirator users was highest for aerosolized medications and lowest for chemical sterilants. Most respondents reported using a surgical mask for at least one of the hazards, with highest use for surgical smoke generated by electrosurgical techniques and ILI. The high proportion of respirator non-users who used surgical masks is concerning because HCWs may be using a surgical mask in situations that require a respirator, specifically for surgical smoke. Improved guidance on hazard recognition, risk evaluation, and appropriate respirator selection could potentially help HCWs better understand how to protect themselves at work.

Effectiveness of Masks and Respirators Against Respiratory Infections in Healthcare Workers: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis quantified the protective effect of facemasks and respirators against respiratory infections among healthcare workers. Relevant articles were retrieved from Pubmed, EMBASE, and Web of Science. Meta-analyses were conducted to calculate pooled estimates. Meta-analysis of randomized controlled trials (RCTs) indicated a protective effect of masks and respirators against clinical respiratory illness (CRI) (risk ratio [RR] = 0.59; 95% confidence interval [CI]:0.46-0.77) and influenza-like illness (ILI) (RR = 0.34; 95% CI:0.14-0.82). Compared to masks, N95 respirators conferred superior protection against CRI (RR = 0.47; 95% CI: 0.36-0.62) and laboratory-confirmed bacterial (RR = 0.46; 95% CI: 0.34-0.62), but not viral infections or ILI. Meta-analysis of observational studies provided evidence of a protective effect of masks (OR = 0.13; 95% CI: 0.03-0.62) and respirators (OR = 0.12; 95% CI: 0.06-0.26) against severe acute respiratory syndrome (SARS). This systematic review and meta-analysis supports the use of respiratory protection. However, the existing evidence is sparse and findings are inconsistent within and across studies. Multicentre RCTs with standardized protocols conducted outside epidemic periods would help to clarify the circumstances under which the use of masks or respirators is most warranted.

Evaluation of Nickel Release from Endobronchial Valves as a Possible Cause of Hypersensitivity Pneumonitis in a Patient Treated with Bronchoscopic Lung Volume Reduction.

BACKGROUND: Endobronchial valve (EBV) placement is an established lung volume reduction procedure aiming to improve lung function and exercise capacity in patients with severe emphysema. As EBVs consist of silicone and nitinol (a metal alloy of nickel and titanium), there are concerns that nickel ions might be released and could have a clinical impact in patients with a contact allergy to nickel. Based on a case with hypersensitivity pneumonitis (HP) after treatment with EBVs, we aimed to evaluate the in vitro nickel release from EBVs using inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy (SEM). METHODS: Six EBVs were immersed in artificial saliva for a period of 7 days. At 24-h intervals, the nickel ion concentration was measured using ICP-MS. RESULTS: There was evidence of a significant nickel release from EBV during the first 48 h, which is possibly due to an incomplete silicone layer detected by SEM. The concentration of released nickel was below the toxic limit. CONCLUSIONS: To the best of our knowledge, we report the first case of HP after EBV treatment. Our finding of in vitro release of nickel ions from EBVs may contribute to the current understanding on hypersensitivity reactions after nitinol implants in patients with nickel contact allergy. However, it did not confirm a causative relationship.

Performance of two respiratory protective devices used by home-attending health care workers (a pilot study).

OBJECTIVES: This pilot study aimed at determining the Workplace Protection Factor (WPF) for respiratory protective devices widely used by health care workers to reduce exposure to potentially hazardous aerosols when attending patients in their homes. Two devices were tested, an N95 filtering facepiece respirator (FFR) and a surgical mask (SM). METHODS: Three home-attending health care workers were recruited, medically cleared and fit tested. At the workplace, the aerosol concentrations outside (Cout) and inside (Cin) of the tested respiratory protective device worn by a subject were measured using two simultaneously operating P-Trak condensation particle counters within the particle size range of approximately 20-1,000 nm. Real-time and integrated (time-weighted average, TWA) values of WPF = Cout/Cin were determined. RESULTS: This pilot study demonstrated that the WPF of the tested N95 FFR consistently exceeded that of the SM. The WPFTWA(C) values calculated for the entire test time (based on the TWA aerosol concentration values) ranged from 29 to 40 and 2 to 9, respectively. In all cases, the N95 FFR provided protection above the Occupational Safety and Health Administration's (OSHA) assigned protection factor of 10, whereas the SM often offered little or essentially no protection against the measured sub-micrometer aerosol particles. For both devices, the protection level was found to depend on activity. For example, the WPFTWA(C) for one subject wearing the N95 FFR was 56 during normal activity but fell almost 70% during tracheal suctioning. It is explicable considering that different procedures implemented by health care workers in homes generate particles of different sizes and require different body movements; both factors are anticipated to affect the WPF. CONCLUSIONS: Wearing an N95-certified respirator helps significantly reduce the aerosol inhalation exposure of home-attending health care workers. An SM offers much lower protection. The WPF depends on several factors, including, but not limited to, the health care worker's activity and/or body movements; the WPF varies from one worker to another.

Behavioural interventions to promote workers' use of respiratory protective equipment.

BACKGROUND: Respiratory hazards are common in the workplace. Depending on the hazard and exposure, the health consequences may include: mild to life-threatening illnesses from infectious agents, acute effects ranging from respiratory irritation to chronic lung conditions, or even cancer from exposure to chemicals or toxins. Use of respiratory protective equipment (RPE) is an important preventive measure in many occupational settings. RPE only offers protection when worn properly, when removed safely and when it is either replaced or maintained regularly. The effectiveness of behavioural interventions either directed at employers or organisations or directed at individual workers to promote RPE use in workers remains an important unanswered question. OBJECTIVES: To assess the effects of any behavioural intervention either directed at organisations or at individual workers on observed or self-reported RPE use in workers when compared to no intervention or an alternative intervention. SEARCH METHODS: We searched the Cochrane Work Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 07), MEDLINE (1980 to 12 August 2016), EMBASE (1980 to 20 August 2016) and CINAHL (1980 to 12 August 2016). SELECTION CRITERIA: We included randomised controlled trials (RCTs), controlled before and after (CBA) studies and interrupted time-series (ITS) comparing behavioural interventions versus no intervention or any other behavioural intervention to promote RPE use in workers. DATA COLLECTION AND ANALYSIS: Four authors independently selected relevant studies, assessed risk of bias and extracted data. We contacted investigators to clarify information. We pooled outcome data from included studies where the studies were sufficiently similar. MAIN RESULTS: We included 14 studies that evaluated the effect of training and education on RPE use, which involved 2052 participants. The included studies had been conducted with farm, healthcare, production line, office and coke oven workers as well as nursing students and people with mixed occupations. All included studies reported the effects of interventions as use of RPE, as correct use of RPE or as indirect measures of RPE use. We did not find any studies where the intervention was delivered and assessed at the whole organization level or in which the main focus was on positive or negative incentives. We rated the quality of the evidence for all comparisons as low to very low. Training versus no trainingOne CBA study in healthcare workers compared training with and without a fit test to no intervention. The study found that the rate of properly fitting respirators was not considerably different in the workers who had received training with a fit test (RR 1.17, 95% Confidence Interval (CI) 0.97 to 1.10) or training without a fit test (RR 1.16, 95% CI 0.95 to 1.42) compared to those who had no training. Two RCTs that evaluated training did not contribute to the analyses because of lack of data. Conventional training plus additions versus conventional training aloneOne cluster-randomised trial compared conventional training plus RPE demonstration versus training alone and reported no significant difference in appropriate use of RPE between the two groups (RR 1.41, 95% CI 0.96 to 2.07).One RCT compared interactive training with passive training, with an information screen, and an information book. The mean RPE performance score for the active group was not different from that of the passive group (MD 2.10, 95% CI -0.76 to 4.96). However, the active group scored significantly higher than the book group (MD 4.20, 95% CI 0.89 to 7.51) and the screen group (MD 7.00, 95% CI 4.06 to 9.94).One RCT compared computer-simulation training with conventional personal protective equipment (PPE) training but reported only results for donning and doffing full-body PPE. Education versus no educationOne RCT found that a multifaceted educational intervention increased the use of RPE (risk ratio (RR) 1.69, 95% CI 1.10 to 2.58) at three years' follow-up when compared to no intervention. However, there was no difference between intervention and control at one year's, two years' or four years' follow-up. Two RCTs did not report enough data to be included in the analysis.Four CBA studies evaluated the effectiveness of education interventions and found no effect on the frequency or correctness of RPE use, except in one study for the use of an N95 mask (RR 4.56, 95% CI 1.84 to 11.33, 1 CBA) in workers. Motivational interviewing versus traditional lecturesOne CBA study found that participants given motivational group interviewing-based safety education scored higher on a checklist measuring PPE use (MD 2.95, 95% CI 1.93 to 3.97) than control workers given traditional educational sessions. AUTHORS' CONCLUSIONS: There is very low quality evidence that behavioural interventions, namely education and training, do not have a considerable effect on the frequency or correctness of RPE use in workers. There were no studies on incentives or organisation level interventions. The included studies had methodological limitations and we therefore need further large RCTs with clearer methodology in terms of randomised sequence generation, allocation concealment and assessor blinding, in order to evaluate the effectiveness of behavioural interventions for improving the use of RPE at both organisational and individual levels. In addition, further studies should consider some of the barriers to the successful use of RPE, such as experience of health risk, types of RPE and the employer's attitude to RPE use.

A New Miniature Respirable Sampler for In-mask Sampling: Part 1-Particle Size Selection Performance.

The Health and Safety Laboratory has developed a miniature respirable sampler to gain a better understanding of the exposure of workers to hazardous substances when they are wearing respiratory protective equipment (RPE) or helmets with visors in the workplace. The study was in two parts and the first part, described herein, was to develop the sampler and test its collection characteristics. Assessment of the impact of the sampler on RPE safety and its comparability with traditional laboratory-based approaches to measure protection factors was discussed in a second article. The miniature sampler (weight-5.4g, length-13mm) was designed to fit into the space available between the nose and chin of an individual inside a filtering facepiece type mask and has a radially omnidirectional inlet with a porous foam particle selector that allows the collection of the respirable fraction on a downstream filter. The sampling efficiency was compared with the respirable convention. A close match with the respirable convention was obtained at a flow rate of 1 l min-1 and the 50% penetration cut off value (d 50) was 4.08 µm. After 3 hours sampling in high humidity (95%), the penetration curve had shifted towards smaller particle sizes (d 50 = 3.81 µm) with 88% of the calculated bias values within 10%. The miniature sampler measured respirable dust and crystalline silica mass concentrations comparable with performance of the Safety In Mines Personal Dust Sampler (SIMPEDS), commonly used in Great Britain, at a flow rate of 0.8 l min-1 The d 50 for the miniature sampler at 0.8 l min-1 (4.4 µm) is within 5% of the d 50 of the SIMPEDS at its prescribed flow rate of 2.2 l min-1 (4.2 µm). These results indicated that the miniature sampler was a good candidate to proceed with tests with RPE described in the second part of this series of two papers.

Performance of N95 FFRs Against Combustion and NaCl Aerosols in Dry and Moderately Humid Air: Manikin-based Study.

OBJECTIVES: The first objective of this study was to evaluate the penetration of particles generated from combustion of plastic through National Institute for Occupational Safety and Health (NIOSH)-certified N95 filtering facepiece respirators (FFRs) using a manikin-based protocol and compare the data to the penetration of NaCl particles. The second objective was to investigate the effect of relative humidity (RH) on the filtration performance of N95 FFRs. METHODS: Two NIOSH-certified N95 FFRs (A and B) were fully sealed on a manikin headform and challenged with particles generated by combustion of plastic and NaCl particles. The tests were performed using two cyclic flows [with mean inspiratory flow (MIF) rates = 30 and 85 l min(-1), representing human breathing under low and moderate workload conditions] and two RH levels (≈20 and ≈80%, representing dry and moderately humid air). The total and size-specific particle concentrations inside (C in) and outside (C out) of the respirators were measured with a condensation particle counter and an aerosol size spectrometer. The penetration values (C in/C out) were calculated after each test. RESULTS: The challenge aerosol, RH, MIF rate, and respirator type had significant (P < 0.05) effects on the performance of the manikin-sealed FFR. Its efficiency significantly decreased when the FFR was tested with plastic combustion particles compared to NaCl aerosols. For example, at RH ≈80% and MIF = 85 l min(-1), as much as 7.03 and 8.61% of combustion particles penetrated N95 respirators A and B, respectively. The plastic combustion particles and gaseous compounds generated by combustion likely degraded the electric charges on fibers, which increased the particle penetration. Increasing breathing flow rate or humidity increased the penetration (reduced the respirator efficiency) for all tested aerosols. The effect of particle size on the penetration varied depending on the challenge aerosol and respirator type. It was observed that the peak of the size distribution of combustion particles almost coincided with their most penetrating particle size, which was not the case for NaCl particles. This finding was utilized for the data interpretation. CONCLUSIONS: N95 FFRs have lower filter efficiency when challenged with contaminant particles generated by combustion, particularly when used under high humidity conditions compared to NaCl particles.

Modeling risk of occupational zoonotic influenza infection in swine workers.

Zoonotic transmission of influenza A virus (IAV) between swine and workers in swine production facilities may play a role in the emergence of novel influenza strains with pandemic potential. Guidelines to prevent transmission of influenza to swine workers have been developed but there is a need for evidence-based decision-making about protective measures such as respiratory protection. A mathematical model was applied to estimate the risk of occupational IAV exposure to swine workers by contact and airborne transmission, and to evaluate the use of respirators to reduce transmission. The Markov model was used to simulate the transport and exposure of workers to IAV in a swine facility. A dose-response function was used to estimate the risk of infection. This approach is similar to methods previously used to estimate the risk of infection in human health care settings. This study uses concentration of virus in air from field measurements collected during outbreaks of influenza in commercial swine facilities, and analyzed by polymerase chain reaction. It was found that spending 25 min working in a barn during an influenza outbreak in a swine herd could be sufficient to cause zoonotic infection in a worker. However, this risk estimate was sensitive to estimates of viral infectivity to humans. Wearing an excellent fitting N95 respirator reduced this risk, but with high aerosol levels the predicted risk of infection remained high under certain assumptions. The results of this analysis indicate that under the conditions studied, swine workers are at risk of zoonotic influenza infection. The use of an N95 respirator could reduce such risk. These findings have implications for risk assessment and preventive programs targeting swine workers. The exact level of risk remains uncertain, since our model may have overestimated the viability or infectivity of IAV. Additionally, the potential for partial immunity in swine workers associated with repeated low-dose exposures or from previous infection with other influenza strains was not considered. Further studies should explore these uncertainties.