Respirator Filters Research Articles

Upscaling of Electrospinning Technology and the Application of Functionalized PVDF-HFP@TiO2 Electrospun Nanofibers for the Rapid Photocatalytic Deactivation of Bacteria on Advanced Face Masks.

In recent years, Electrospinning (ES) has been revealed to be a straightforward and innovative approach to manufacture functionalized nanofiber-based membranes with high filtering performance against fine Particulate Matter (PM) and proper bioactive properties. These qualities are useful for tackling current issues from bacterial contamination on Personal Protective Equipment (PPE) surfaces to the reusability of both disposable single-use face masks and respirator filters. Despite the fact that the conventional ES process can be upscaled to promote a high-rate nanofiber production, the number of research works on the design of hybrid materials embedded in electrospun membranes for face mask application is still low and has mainly been carried out at the laboratory scale. In this work, a multi-needle ES was employed in a continuous processing for the manufacturing of both pristine Poly (Vinylidene Fluoride-co-Hexafluoropropylene) (PVDF-HFP) nanofibers and functionalized membrane ones embedded with TiO2 Nanoparticles (NPs) (PVDF-HFP@TiO2). The nanofibers were collected on Polyethylene Terephthalate (PET) nonwoven spunbond fabric and characterized by using Scanning Electron Microscopy and Energy Dispersive X-ray (SEM-EDX), Raman spectroscopy, and Atomic Force Microscopy (AFM) analysis. The photocatalytic study performed on the electrospun membranes proved that the PVDF-HFP@TiO2 nanofibers provide a significant antibacterial activity for both Staphylococcus aureus (~94%) and Pseudomonas aeruginosa (~85%), after only 5 min of exposure to a UV-A light source. In addition, the PVDF-HFP@TiO2 nanofibers exhibit high filtration efficiency against submicron particles (~99%) and a low pressure drop (~3 mbar), in accordance with the standard required for Filtering Face Piece masks (FFPs). Therefore, these results aim to provide a real perspective on producing electrospun polymer-based nanotextiles with self-sterilizing properties for the implementation of advanced face masks on a large scale.

Designed for a pandemic: Mitigating the risk of SARS-CoV-2 transmission through hospital design and infrastructure

BackgroundTo describe the new Royal Adelaide Hospital (RAH) design and infrastructure features that helped mitigate the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission within the hospital during the pre-vaccination and pre-antiviral period. MethodThe RAH infrastructure, design and initial pandemic response was assessed. A retrospective review of all confirmed or suspected coronavirus disease 2019 (COVID-19) patients admitted from 1 February 2020 to 30 May 2020 was also performed to assess risk of transmission. Outbreak response reports were reviewed to identify episodes of nosocomial COVID-19. ResultsKey infrastructure features include single-bed overnight rooms with dedicated bathrooms, creation of pandemic areas accessible only to pandemic staff, and sophisticated air-handling units with improved ventilation. A total of 264 COVID-19 related admission occurred, with 113 confirmed cases and 1579 total cumulative bed days. Despite a limited understanding of SARS-CoV-2 transmission, no vaccination or anti-viral therapy, global shortages of particulate filter respirators and restricted testing during this period, only one probable nosocomial COVID-19 case occurred in a healthcare worker, with no nosocomial cases involving patients. ConclusionsThe RAH design and pandemic features complimented existing infection control interventions and was important in limiting nosocomial spread of SARS-CoV-2.

Mathematical model of air flow movement in a motorized filter respirator

Purpose. Development of a mathematical model of the air flow movement in a motorized filter respirator (hereinafter referred to as MFR), which allows ensuring the control of the fan parameters, taking into account external and internal influences on the duration of the protective action and favourable operating conditions. Methodology. To describe linear objects of the “input-output” type, it is convenient to use their transfer functions as mathematical models. In this case, to determine the mathematical description of the MFR operation, two tasks need to be solved. The first is related to finding the structure of the mathematical model, and the second involves determining the coefficients of the polynomials in the numerator and denominator of the transfer function that describes the motion of the air flow in the MFR. Findings. A mathematical model of airflow in a MFR has been developed in the form of a transfer function of the third order; it can be used to develop a pressure control system for the air in the under-mask space in accordance with the user’s work mode in order ensure comfortable working conditions. The presented mathematical model of airflow in the MFR differs from the existing approaches by taking into account the influence of the following external and internal parameters of the system on the performance indicators: the user’s work mode, atmospheric pressure, filter resistance, pressure drop in air ducts with the effect of air accumulation in the under-mask space based on the “capacity-resistance” principle. Numerical coefficients of the mathematical model of airflow in the air duct of the MFR have been determined, which allow adjusting the number of fan rotations according to the time of operation, the increase in resistance on the filters, and the operating mode. Originality. A correlation has been established between the external and internal parameters of the MFR: atmospheric pressure, pressure drop in the air duct, filter resistance, and the user’s work mode with the effect of air accumulation in the sub-mask space reflected according to the “capacity-resistance” principle. Practical value. The parameters of the mathematical model have been determined, which can be used when developing a control system for the airflow movement in the MFR: changes in air flow rate in accordance with different conditions of physical exertion of the user when performing professional activities.

INDIVIDUAL RESPIRATORY PROTECTION EQUIPMENT: INNOVATIONS TO REDUCE THE RISK OF OCCUPATIONAL DISEASES

Individual respiratory protective equipment (PPE) is the last barrier to protect workers when performing production tasks in harmful and dangerous working conditions. The article analyzes modern innovative designs of personal respiratory protective equipment, which increase the level of protection of users during their operation. The method of morphological analysis is applied. This method based on the selection of possible solutions for assessing the manufacturability of PPE models (if there is a system of criteria) and making a rational decision regarding the features of their application in production conditions. As a result, it was established that in order to ensure the appropriate duration of the protective action of gas and dust filters and to avoid both poisoning of workers due to the ingress of harmful aerosols into the sub-mask space of the filter respirator, and excessive physical exhaustion due to the increase in pressure drop above the standard substances, it is recommended to equip the filters with special indicators for determining air pollution and pressure drop values. It was determined that in order to increase the reliability of the protection of workers, it is necessary to equip filter respirators with the functions of operational control of breathing resistance, place a headrest to control the occurrence of possible gaps behind the obturation band when performing various production operations, and establish the real term of the protective effect of the filters. The practical value of the work is innovative solutions to improve the designs of existing filter respirators, which will allow control over technological parameters during operation. In particular, the density along the obturation strip and the magnitude of the tension force of the respirator headgear. Recommendations are also given for controlling the term of the protective action of gas filters, since determining the specified indicators based on the organoleptic abilities of the user is dangerous for health. Keywords: risk, means of individual protection of respiratory organs, filtering respirator.

Improvement of motorized design filtering respirator

Working conditions, in terms of hygiene, harmful impurities in the air of the working area, often do not meet regulatory requirements. In such cases, motorized filter respirators are used to protect respiratory organs, which require the development of an appropriate system for managing operational indicators for effective operation. The purpose of the article was to improve the control system of a motorized filter respirator to increase protective efficiency, due to the development of a new parametric scheme of the control object, taking into account the functional relationships between the operating mode, air flow, filter resistance and the term of protective action. To create an appropriate control system, a structural-parametric synthesis of operational indicators management was applied, based on the relationships between the main variables (outgoing regulated variables, controlling influences and disturbances). A new working diagram of the control object with selected design elements of the blower has been developed, the main difference of which is the use of the “Arduino Uno R3” board, the “LCD Keypad Shield” module with a two-line display for controlling the air flow modes, in accordance with the change of the filter resistance taking into account the accumulation dust deposit based on the assumption that the transfer function can be represented by an aperiodic link of the 1st order with sufficient accuracy for practice. To work out the operating modes and determine the duration of the protective effect, a software model of the operation of the motorized filter respirator was created, which made it possible to evaluate the influence of the dust concentration on the change in air flow through the filter elements, taking into account the accumulation of dust sediment on the protective effectiveness. Recommendations have been developed to ensure the effective functioning of the protective device in accordance with the requirements under the most unfavorable conditions. The practical value of the work lies in the fact that the modes of movement of the air flow are determined, in accordance with the speed of rotation of the fan blade from the width of the PWM pulses, which depend on the resistance of the filter, the accumulation of dust deposits based on the transfer function

INCREASING THE INSULATION PROPERTIES OF FILTER RESPIRATORS TO PROTECT MINERS’ RESPIRATORY ORGANS FROM DUST

To increase the insulating properties of elastomeric half-masks, it is suggested to perforate the obturator in the area of the nasal bridge, chin and cheeks, which allows for adjustment in its size, thus preventing the occurrence of wrinkles on the user’s face in the areas which are the individual features of a particular user’s face. Three versions of the perforated filter respirator obturator have been proposed: in the first, the holes are made along the entire perimeter of the obturator; in the second, the holes are only in the area of the cheeks and nasal bridge; in the third, incisions with a diameter of 5 mm are made in the area of the nasal bridge and cheeks. The result of modelling a set of alternative solutions taking into account the coefficient of protection of filter respirator half-masks, the distribution of compressive forces, which are determined in the environment of the packages “ANSYS” and “Solid works”, has been obtained on the basis of main indicators of the proposed models. To make a decision on choosing the best model, the mass of the elastomeric half mask, its dimensions and the complexity of the design were additionally considered. On the basis of expert evaluation, according to the described procedure for determining the utility function of the factors from their values, it has been defined that the second model of the half-mask is characterized by the best parameters. Conducted laboratory studies to determine the aerosol absorption coefficient by the obturation line showed the lowest indicator in the second option.

The measuring aerosol spreading during countermeasures (MASC) study presents an automated system to investigate face mask efficacy and other aerosol countermeasures in varying environments.

The COVID-19 pandemic exemplified the importance of research on personal protective equipment. In specific, understanding how effective surgicalmasks or particulate filter respirators are at reducing the transmission of infectious diseases has suddenly become one of the most pressing issues for legislators, regulators, and everyday life. However, there was a lack of available scientific platforms to assess this issue. Therefore, we designed and built a system entitled MASC: measuring aerosol spreading during countermeasures. This platform allows the simulation of various everyday situations and evaluation of the efficacy of masks and respirators in reducing the amount of inhaled particulate matter from the air. Furthermore, MASC can be used to investigate how aerosols propagate in closed spaces, such as offices or classrooms. It can be used to generate aerosols on command and control the room temperature, humidity, and wind speed. Up to four laser aerosol spectrometers can be read simultaneously, and a camera can automatically take pictures to evaluate the efficacy of countermeasures to prevent the spread of aerosols. The aerosol generation, measurement periods, and the number of repetitions for an experiment can be configured digitally and are executed by a computer automatically. A website displays the data in real time and allows monitoring of the experiment. Upon completion, statistical values are calculated automatically to accelerate the evaluation of the gathered data. Codes and technical drawings in this present methodology publication are open source and can be used by the scientific community to establish similar systems.

Performance evaluation of surgical, N95 and FFP2 respiratory masks by manikin-based sampling system for assessing the protection against airborne dust

In this study, the particle penetration through various respirator filters (N95, FFP2 and surgical) were measured by manikin-based sampling system. In the months of June to November, 102 samples were taken for 44 days. A specific flow (9 L per minute) of air containing suspended particles (about 1.05 m3) was passed through the breathing filters and the particle leakage was determined. The personal cascade impactor (Sioutas, SKC) was utilized in order to classification of penetrated particles in the ranges of 2.5, 1 and 0.5 μm. Protective performance of masks installed on the manikin face is increased from the surgical to the N95 and the FFP2 mask. There was no significant difference between the performance of N95 and FFP2 but there is a significant difference between performances of these two masks with surgical mask. Due to the non-flexibility of the N95 and its lack of fixation on the face, the amount of penetration is higher than FFP2. Despite of lower price (FFP2 0.4 $, surgical 0.1 $, N95 0.6 $) and structural feature (double layer structure), FFP2 has the highest performance amongst the three types of masks studied. The results suggest the use of FFP2 masks to protect against dust contamination.

Simple fabrication of an electrospun polystyrene microfiber filter that meets N95 filtering facepiece respirator filtration and breathability standards.

During the global spread of COVID-19, high demand and limited availability of melt-blown filtration material led to a manufacturing backlog of N95 Filtering Facepiece Respirators (FFRs). This shortfall prompted the search for alternative filter materials that could be quickly mass produced while meeting N95 FFR filtration and breathability performance standards. Here, an unsupported, nonwoven layer of uncharged polystyrene (PS) microfibers was produced via electrospinning that achieves N95 performance standards based on physical parameters (e.g., filter thickness) alone. PS microfibers 3-6μm in diameter and deposited in an ~5 mm thick filter layer are favorable for use in FFRs, achieving high filtration efficiencies (≥97.5%) and low pressure drops (≤15 mm H2O). The PS microfiber filter demonstrates durability upon disinfection with hydroxyl radicals (•OH), maintaining high filtration efficiencies and low pressure drops over six rounds of disinfection. Additionally, the PS microfibers exhibit antibacterial activity (1-log removal of E. coli) and can be modified readily through integration of silver nanoparticles (AgNPs) during electrospinning to enhance their activity (≥3-log removal at 25 wt% AgNP integration). Because of their tunable performance, potential reusability with disinfection, and antimicrobial properties, these electrospun PS microfibers may represent a suitable, alternative filter material for use in N95 FFRs.

A risk of pulmonary diseases in miners while using dust respirators

Purpose. To determine magnitudes of the occupational risks of respiratory disease (pneumoconiosis) occurrence in miners while using filter respirators on the basis of an exposure dust dose with the consideration of work experience. Methodology. To assess occupational risks, a new approach proposed by the Research Institute of Complex Hygiene and Occupational Diseases is used. The approach is based on determining an exposure dose of a hazardous substance entering the workers lungs during their professional contact with it taking into account the volume of pulmonary ventilation, the number of shifts, and work experience. Findings. Use of dust respirators reduces the risk of occupational respiratory diseases but does not eliminate it completely. It has been established that with more than three-year work experience and coal dust concentrations of more than 50 mg/m3, use of dust filter respirators does not ensure a minimal degree of the occupational disease risks. At the same time, it has been identified that if work experience is less than 3 years with the use of filter respirators, the risk of occupational diseases will be minimal. It has been proved that the risk assessment should involve using the minimal value of a protection factor of a respirator, which is fixed in the production environment. It has been shown that working within the areas with dust concentrations higher than 100 mg/m3 is dangerous for miners; over time, with the accumulation of sufficient dust in the lungs it will lead to the development of silicosis. Originality. It consists in scientific substantiation of the magnitude of occupational risk of respiratory diseases in miners, taking into account a real protection factor of respirators, which is determined at the workplace based on the calculation of an exposure dose and time of professional contact with hazardous substances. Practical value. The experience of safe operation in mine workings with and without using filter respirators has been substantiated, basing on a safe value of coal dust concentration, at which a low level of occupational risk of respiratory diseases is recorded. Recommendations for determining the dust load taking into account a protection factor of respirators at the workplace have been developed.

Filtration efficiency of N95 filtering facepiece respirators during multi-cycles of ‘8-hour simulated donning + disinfection’

BackgroundAerosol-borne diseases such as COVID-19 may outbreak occasionally in various regions of the world, inevitably resulting in short-term shortage and corresponding reuse of disposable respirators.AimTo investigate the effective disinfection methods, reusable duration and frequency of N95 respirators.MethodsBased on the self-built respirator simulation test system, and under combinations of experimental conditions of three N95 respirators × 0–200 nm NaCl aerosols × three simulated breathing flow rates (15, 50 and 85 L/min) × two disinfection methods (dry heating and ultraviolet (UV) radiation), this study continuously measured the changes in filtration efficiency of all respirators during multi-cycles of ‘8-h simulated donning + disinfection’ until the penetration reached ≥5%.FindingsMulti-cycles of dry heating and UV radiation treatments on the reused (i.e., multiple 8-h donning) N95 respirators had a minimal effect (<0.5%) on the respirator filtration efficiency, and even at 85 L/min, all tested N95 respirators were able to maintain filtration efficiencies ≥95% for at least 30 h or four reuse cycles of ‘8-h donning + disinfection’, while a lower breathing flow rate (15 L/min) plus the exhalation valve could further extend the N95 respirator's usability duration up to 140 h or 18 reuse cycles of ‘8-h donning + disinfection’. As the respirator wearing time extended, aerosol penetration slowly increased in a quadratic function with a negative second-order coefficient, and the penetration increment during each cycle of 8-h donning was less than 0.9%.ConclusionMulti-cycles of N95 respirator reuse in combination with dry heating or UV irradiation disinfection are feasible.

Filtration performance and breathing resistance of elastomeric half mask respirator P100 filter cartridges after repeated and extended use in healthcare settings

In 2020, the Centers for Disease Control and Prevention recommended the use of the National Institute for Occupational Safety and Health-certified Elastomeric Half Mask Respirators equipped with N95 or P100 respirator filter cartridges for protection against the SARS-CoV-2 viral agent, as a viable alternative to N95 filtering facepiece respirators. Additionally, the Centers for Disease Control and Prevention recommendations stated that based on current practice, it was acceptable to repeatedly use these filter cartridges for up to 12 months as a contingency capacity strategy during anticipated respirator shortages. To validate this recommendation, an investigation was undertaken in which Elastomeric Half Mask Respirators equipped with P100 respirator filter cartridges were deployed and used by healthcare professionals in clinical settings (i.e., inpatient nursing units, operating rooms) for extended periods. These filter cartridges were subsequently tested to accurately quantify their filtration efficiency and breathing resistance to determine if they continued to meet National Institute for Occupational Safety and Health’s performance requirements. Findings from this investigation confirmed that an Elastomeric Half Mask Respirator when equipped with a P100 filter cartridge continues to provide a high level of aerosol filtration performance (≥99.97%) and exhibits little change in breathing resistance even after 12 months of repeated use (i.e., wear, cleaning, and disinfection between patient use and at the end of work shift) in healthcare settings.

C&amp;EN talks with Simon Smith, respirator filter expert

Simon Smith has a long history of developing personal protective equipment (PPE) for industrial, health-care, military, emergency response, and other applications. He specializes in respirator filters and says he finds great satisfaction in the opportunity to apply “dry” science to products that improve health and safety and sometimes save lives. Smith, 60, earned a bachelor’s degree in chemistry from what is now Imperial College London, then a doctorate in chemistry from the University of Manchester Institute of Science and Technology in 1985. After a postdoctoral fellowship at the Royal Military College of Canada, he joined Racal Health and Safety. The company was purchased by 3M in 1998. Smith retired from 3M in late 2019 but remains active in standards development with the International Organization for Standardization, the CSA Group (formerly the Canadian Standards Association), and other national and international health and safety organizations. Jeff Johnson spoke with Smith about developing

Respirator filter expert Simon Smith explains what’s in a mask and what drives personal protective equipment R&amp;D

Respirator filter expert Simon Smith explains what’s in a mask and what drives personal protective equipment R&amp;D

Assessing changes to N95 respirator filtration efficiency, qualitative and quantitative fit, and seal check with repeated vaporized hydrogen peroxide (VHP) decontamination

N95 respirators were reprocessed using vaporized hydrogen peroxide to supplement limited supplies during the COVID-19 pandemic. In this study, we found no statistically significant differences in qualitative and quantitative fit or filtration efficiency with reprocessing. Filtration efficiency remained above 95% even at 25 cycles of reprocessing without statistically significant change from cycle 20-25 compared to cycle 0 (P=.10, P=.05, respectively). Vaporous hydrogen peroxide is an effective option to augment N95 respirator supplies.

The Effect of Sanitizing Treatments on Respirator Filtration Performance.

The potential for alcoholic vapors emitted by common sanitizing treatments to deteriorate the (electrostatic) filtration performance of disposable respirator masks has been investigated. Reports in the literature and some standard test methods provide a confusing and ambiguous picture concerning the relevance of this effect. Four different types of exposure were investigated in this study to clarify the effect of alcoholic vapor emissions on respirator masks. These included exposure to saturated vapors, use of hand sanitizers, cleaning of table surfaces and sanitization of masks by spraying them with alcohol-containing solutions. Methods employed were designed to be as real-world oriented as possible while remaining reproducible. Filtration performance and deterioration effects on exposure to the different treatments were determined on three different types of certified commercial respirator masks—a P2 and two KN95 masks. This study provides substantial evidence that disposable respirator masks with an accepted performance rating are seriously compromised from an exposure to saturated alcoholic vapors, can tolerate a one-off spray treatment with an alcoholic solution and retain their attested protection under the influence of alcoholic vapors from the use of hand sanitizer or spray sanitizer. Considering the range of vastly different outcomes obtained from the four treatments investigated, it seems prudent to assess in each case the specific effects of alcoholic solution treatments and vapors on respirator masks before use.

ВИБІР РЕСПІРАТОРІВ НА ОСНОВІ РЕЗУЛЬТІВ ВИМІРЮВАННЯ АНТРОПОМЕТРИЧНИХ РОЗМІРІВ СЕРЕДНЬОСТАТИСТИЧНОГО РОБІТНИКА АКХЗ ТА ШЕФФІЛДІВСЬКОГО МАНЕКЕНУ ГОЛОВИ

Purpose. Determination of the anthropometric distribution of the average Ukrainian worker to increase the reliability of the calculation of the protection factor of respirators due to the improvement of the procedure for laboratory assessment of the penetration factor. Methods. A comparison has been made of the method of selecting respirators based on the methods of mathematical statistics and statistical analysis to establish relationship between the anthropometric dimensions of the users' faces and the Sheffield mannequin of the head, in accordance with the ISO 16900-1:2020 standard "Respiratory protective devices - Methods of test and test equipment - Part 1: Determination of inward leakage" and the Technical Regulations. Results. The procedure for determining the penetration factor of respirators from the selection of the appropriate type of the Sheffield mannequin and the evaluation of the suction coefficient has been improved with regard to the selection of the number of testers who would ensure the compliance of the design parameters of the respirators with the anthropometric parameters of the face of possible users. The determined anthropometric distribution of the average Ukrainian worker for adjusting the parameters (cell size and number of testers in the cells) of the known parametric table for the selection of testers, in relation to conducting a laboratory study to determine the suction coefficient of half-mask respirators by the obturation band or valve system (if available). Scientific novelty. Improving the reliability of studies on the determination of the protection factor of personal respiratory protective devices (RPD) (filtering respirators) is an urgent task. However, in the domestic standards for determining the quality of RPD, there are no data on the anthropometric dimensions of the faces of Ukrainian workers, the Sheffield mannequin of the head, and the requirements for the faces of volunteer testers. The consequence of this is the discrepancy between the technical characteristics of the respirators declared by the developer and the actual ones obtained during their operation in production conditions. Practical significance. On the basis of the obtained data regarding 400 typical users of RPD, workers of Avdiivka Coke and Chemical Plant (ACCP) aged 20 to 55 years, their distribution by length and width of faces has been revealed. According to the results of the research, in which twenty-five volunteers, selected according to ten parameters, took part, the anthropometric dimensions of the face of the average worker of the ACCP and the corresponding Sheffield mannequin of the head have been determined.

УДОСКОНАЛЕННЯ ПРОЦЕДУРИ ВИБОРУ ФІЛЬТРУВАЛЬНИХ ПРОТИПИЛОВИХ РЕСПІРАТОРІВ НА ОСНОВІ ОЦІНКИ РИЗИКІВ

Purpose. The improvement of the procedure for selection of dust filter respirators with taking into account the risks in the workplace. Methodology. To determine the best method for risk assessment, the review of scientific publications has been done; the scientific works that have been conducted on the problem by some institutes of hygiene in recent years, have also been studied; discussions on improving the operating conditions of respirators with scientists from the institutes of occupational health and specialists in labor protection of industrial enterprises of the coal industry have been held. Results. The procedure for the selection of dust filter respirators, which consists of three main steps, has been developed. This allows taking into account the whole set of influential factors of the production environment when assessing the risk and choice of personal respiratory protection. It differs from the existing ones in the ability to take into account operational risks that increase the intensity of work, which can affect the physical health of the user. To assess the operational risks, it has been proposed to use five main indicators of dust filter respirators: duration of work, limitation of the field of view, resistance to respiration, weight, and CO2 content. The main types of errors in the selection and operation of dust filter respirators have been identified. It can significantly reduce the effectiveness of protection of respirator users. Scientific novelty. It is a scientific basis for the procedure for selecting dust filter respirators based on an assessment of operational risks to workers, taking into account the impact of environmental factors that can lead to errors in the choice and operation of personal respiratory protection. Practical significance. Recommendations for the selection of dust filter respirators based on risk assessment have been developed. Risk assessment includes the following main steps: identification of the harmful factor, determination of the type of hazard to the worker and calculation of operational risk, as well as selection and justification of the protective device model. In addition, some typical errors in the selection and operation of personal respiratory protection means have been described, which can significantly impair the level of protection of users. Recommendations for assessing the operational risks of dust filter respirators, which increase the intensity of work, have also been worked out.

Improving the effectiveness of the protective properties of filter respirators due to their treatment with impregnating solutions

Improving the effectiveness of the protective properties of filter respirators due to their treatment with impregnating solutions

OPTIMISING THE DESIGN PARAMETERS OF A FILTER RESPIRATOR

Purpose. The optimum length choice of the headband insert for a dust filter respirator. Design/methodology/approach. The method of experimental planning has been applied to determine the interpolation (regression) and optimisation dependencies of the filter respirator process. The dominant variables for the respirator were selected based on experimental studies. Input controlled variables for mathematical model are length of tape insertion and headband tension force, output parameter is volume of contaminated air suction under face mask. A regression power relationship between the variables has been established. The recall function was approximated by a second-order non-linear mathematical model. The method of least squares was applied in determining the coefficients at the control variables. Regression dependencies and additional constraints on protective and ergonomic requirements have been used in the optimisation calculations. Conclusions. The solution of the set tasks were the following results: the nonlinear mathematical model more adequately characterizes the respirator use process compared to the linear model of the first order. Relative error between experimental and calculated values of air intake does not exceed 0.6 %. The optimization task is formulated with the regression model. The target function and constraints have been defined with safety and ergonomic requirements. The target function does not have an extremum within the defined constraints. The optimum insertion length was determined graphically and was 2–3.2 cm, the headband tension force does not exceed 5 H With this parameter. Research limitations/consequences. The proposed method is universal in determining the optimum parameters for all types of personal protective equipment. Practical implications: the choice of respirator design parameters can be made using experimentation-surface fitting. Originality/value. The proposed method makes it possible to decline heuristic design methods and establish analytical relationships between the requirements and parameters of individual elements of personal protective equipment.