Effect of the Sorption Layer on the Protection Time Provided by Anti-Smog Half-Masks.

This paper presents the results of a study examining the protection time of half-masks containing different types and quantities of carbon sorbents. The protection time afforded by the half-masks was determined by analyzing the adsorption of three substances harmful to human health at their maximum allowable concentrations. Two of the tested half-masks showed comprehensive protection against pollutants contained in smog. Among the tested half-masks, the one with the best protective properties was identified. The longest protection time (over 8 h) was recorded for toluene, followed by over 7 h for sulfur dioxide, and only 2 h for cyclohexane. The morphological structure of nonwovens incorporating the carbon sorbents was examined under a microscope. The study showed that protection time depends on the size of activated carbon particles incorporated in the nonwoven structure as well as on their distribution. Based on these results, we identified the most effective morphological structure of the sorbent in the nonwovens.

Analysis of the Resistance Change of Chemosensitive Layers to the Presence of Ammonia Vapors under Variable Conditions of Air Temperature and Humidity.

The developed chemosensitive layers consisted of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), and a conductive polymer (polyaniline-PANI) in a polymeric matrix (a polystyrene solution in methylene chloride). The layers were challenged with a test gas to determine the optimum variant in terms of sensitivity to the selected analyte and the repeatability of results. In terms of individual components, the greatest percentage change in resistance (32%) and the best repeatability were found for chemosensitive layers containing a PANI salt in the polymeric matrix. Even greater changes in resistance were exhibited by sensors containing more than one active component in the matrix: 45% for PANI + MWCNTs and 75% for PANI + rGO. The presented method of thin-layer deposition was shown to be suitable for the production of sensitive and functional sensors of ammonia vapors. The developed sensors were characterized by high repeatability and sensitivity to a harmful substance that constitutes an inhalation hazard to workers. The sensors were also analyzed for their durability and recovery as well as the ability to function under varying temperature and humidity conditions.

Influence of Carbon Sorbent Quantity on Breakthrough Time in Absorbent Filters for Antismog Half Mask Application.

In this article, we present polymer non-woven fabrics with the addition of carbon sorbents being tested to estimate the breakthrough time and efficient protection against vapors present in smog. For this purpose, three substances were selected, which constitute an inhalation hazard and are smog components: cyclohexane, toluene, and sulfur dioxide. It was demonstrated that an increased quantity of carbon sorbent in polymeric filters significantly prolongs the breakthrough time. However, high sorbent quantities may increase the filter surface mass and air flow resistance. To optimize the protective parameters with functionality, a compromise between the two has to be found. By comparing the breakthrough times for different carbon sorbent quantities, the optimal filter composition was elaborated. The analyzed non-woven fabrics were manufactured by the melt-blown process and filled with ball-milled carbon sorbents supplied directly into the fabric blowing nozzle. Both protective performance and textural properties were analyzed for two commercially available carbon sorbents. Furthermore, it was proven that high values of sorbent-specific surface area translates directly into greater filter performance.

Determination of paraffin oil mist penetration at high flow rates through air-purifying respirators.

This article presents paraffin oil mist penetration tests of commercially available air-purifying respirators of different construction conducted using the method described by Standard No. ISO 16900-3:2012, which incorporates flow rates (up to 255 l/min) of test aerosol. The testing method reflects differences in work intensity during the use of respirators. Moreover, the experimental stand, designed according to the international specifications, is described. The results show that the higher the paraffin oil mist flow rate, the higher the penetration index, irrespective of the testing method used and the type of respirator investigated. While at high flow rates, filtering half masks of the first protection class (FFP1) met the requirements of their protection class according to European Standard No. EN 149:20001+A1:2009, filtering half masks of the second and the third protection class (FFP2 and FFP3) did not.

Application of Olfactometry to Assess the Anti-Odor Properties of Filtering Facepiece Respirators Containing Activated Carbon Nonwovens.

Filtering facepiece respirators (FFR) with anti-odor properties are used to reduce odor nuisance occurring both in everyday life and at workplaces. Unfortunately, there are no standardized methods to measure the efficiency of odor reduction of such personal protective devices. This paper aims to determine whether olfactometric-based methods, commonly used in environmental studies, can be employed for this purpose. The proposed procedure is based on the detection of n-butanol by study participants, and it consists of three subsequent stages: (i) defining the individual levels of odor sensitivity of each study participant; (ii) determining THE odor detection level while using FFRs with varying anti-odor properties; and (iii) completing a questionnaire concerning the subjective perceptions of study participants. As a measure of odor reduction efficiency, a coefficient W, defined as a quotient of the degree of odor reduction by the FFR, and the individual odor sensitivity of the subject, was proposed. The experimental results showed the ability of our measure to differentiate the effectiveness of odor reduction of tested FFRs. This indicates that it can be potentially employed as the assessment tool to confirm the effectiveness of such respiratory protective devices as a control measure mitigating the adverse effects of malodors on workers' health, cognition, and behavior.

Chemosensitive Thin Films Active to Ammonia Vapours.

The paper presents various dispersive systems developed for sensing toxic substance-ammonia. Polycarbonate dissolved in methylene chloride was used as a polymer matrix, which was enriched with: multi-walled carbon nanotubes (MWCNs), reduced graphene oxide (rGO) and conductive polymer (polyaniline-PANi). Dispersive systems were applied to the prefabricated substrates with comb electrodes by two methods: spraying and drop-casting, forming an active chemosensitive to ammonia vapours films. The spraying method involved applying the dispersion to the substrate by an aerograph for a specific time, whereas drop-casting involves depositing of the produced dispersive systems using a precision automatic pipette. The electrical responses of the obtained films were examined for nominal concentrations of ammonia vapours. Different types of dispersions with various composition were tested, the relationships between individual compounds and ammonia were analysed and the most promising dispersions were selected. Sensor containing rGO deposited by drop-casting revealed the highest change in the resistance (14.21%).

Multifunctional Polymer Composites Produced by Melt-Blown Technique to Use in Filtering Respiratory Protective Devices.

In this work, a multifunctional polymer composite is made using melt-blowing technology from polypropylene (88 wt.%) and poly (ethylene terephthalate) (12 wt.%) with the addition of functional modifiers, that is, 3 g of a superabsorbent polymer and 5 g of a biocidal agent (Biohaloysite). The use of modifiers is aimed at obtaining adequate comfort when using the target respiratory protection equipment (RPE) in terms of microclimate in the breathing zone and protection against harmful aerosols including bioaerosols. The developed production method is innovative in that the two powdered modifiers are simultaneously applied in the stream of elementary polymeric fibers by two independent injection systems. Aerosols of the modifiers are supplied via a specially designed channel in the central segment of the die assembly, reducing the amount of materials used in the production process and saving energy. The results show that the proposed method of incorporating additives into the fiber structure did not adversely affect the protective and functional properties of the resulting filtration nonwovens. The produced nonwoven composites are characterized by SEM, FTIR, and differential scanning calorimetry (DSC). Given their high filtration efficiency at 5%, satisfactory airflow resistance (~200 Pa), very good antimicrobial activity, and excellent water absorption capacity, the obtained multifunctional nonwoven composites may be successfully used in filtering respiratory protective devices.

Adsorption Performance of Activated-Carbon-Loaded Nonwoven Filters Used in Filtering Facepiece Respirators.

Filtering nonwovens loaded with activated carbon are among the most popular materials used in the construction of filtering facepiece respirators (FFRs) with anti-odour properties that can be used for respiratory protection at workplaces where the occupational exposure limits of harmful substances are not exceeded. Such FFRs, in addition to a polymer filter material of varying effectiveness, also contain a layer of activated-carbon-loaded nonwoven filter, which limits the quantity of chemical compounds entering the breathing zone. The aim of this work was to analyse the influence of challenge concentration (20-120 ppm), relative humidity (2-70%), flow rate (20-55 L/min), and flow pattern (steady-state and pulsating) on the breakthrough of polymer/carbon nonwovens. A commercial activated-carbon-loaded nonwoven filter was used in this study. Its morphology and textural parameters were determined using optical microscopy, image processing, and nitrogen adsorption/desorption measurements at 77 K. Breakthrough experiments were carried out using cyclohexane vapours to assess adsorption characteristics of polymer/carbon media. The results showed that the breakthrough times decreased with increasing challenge concentration (up to 30%), relative humidity (up to 73%), and flow rate (up to 72%). The pulsating flow pattern was found to be more favourable in terms of odour reduction efficiency (up to 30%). The results indicate that all of these factors should be considered during selection and performance assessment of respirators used for odour relief.

Ergonomics assessment of composite ballistic inserts for bullet- and fragment-proof vests.

Personal protective equipment worn by uniformed services (e.g., the police and the military) must ensure protection against bodily injuries. However, a high degree of protection is always associated with significant discomfort. This article presents the results of an assessment of the ergonomics parameters of new special purpose products, ballistic inserts with improved ballistic resistance, and an assessment of the impact of the burden related to their use on the psychomotor performance of the subjects. An obstacle course and subjective ergonomics assessment questionnaires were used in tests. Thermal discomfort was also assessed. Psychological testing included tests enabling an assessment of the subjects' cognitive and psychomotor performance, and a subjective assessment of mental load. The tests did not show any decrease in the comfort of use of the new inserts with improved ballistic resistance compared to the inserts currently used.

Efficiency of filtering materials used in respiratory protective devices against nanoparticles.

The basic aim of this research was to establish the efficiency of filtering materials widely used in respiratory protection devices with particular interest in their porosity, degree of electric and changeable process parameters, such as the flow rate of the test nanoaerosol and the size range of nanoparticles. Tests were carried out with an NaCl solid aerosol of 3.2 × 105 particles/cm3 for the range of particle size of 7-270 nm, at aerosol flow rate of 1800, 2700, 3600, 4500 and 5400 L/h. The tests showed that electrospun nonwovens were the most effective filtering materials for nanoparticles over 20 nm. Melt-blown electret nonwovens with lower porosity than electrospun nonwovens had higher values of penetration of 1%-4%. Those materials provided very efficient protection against nanoparticles of certain sizes only.

New filtering antimicrobial nonwovens with various carriers for biocides as respiratory protective materials against bioaerosol.

This study evaluated the bioactivity of polypropylene melt-blown filtering nonwovens used in respiratory protective devices (RPD) with a biocidal agent (alkylammonium microbiocides) on 2 mineral carriers. Two types of carriers were tested: a bentonite, with an aluminosilicate base, and a perlite, volcanic glass. High biostatic and biocidal effects of modified nonwovens with biocides were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. Nonwovens modified with a biocide on a bentonite carrier showed an opposite reaction to a biocide on a perlite. The research also showed that 10% concentration of a biocidal agent on a perlite carrier was sufficient to inhibit the growth of bacteria (100% reduction) placed in the structure of a filtering material during normal use of RPD. A comparison of the biological activity of 2 filtering materials, each containing 10% of a perlite and produced in a laboratory and industrial conditions, showed no statistically significant differences.

Aspects of tests and assessment of filtering materials used for respiratory protection against bioaerosols. Part I: type of active substance, contact time, microorganism species.

This paper presents the results of a study on antimicrobial activity of polymer filter nonwovens produced by needle-punching or melt-blowing with an addition of disinfecting agents. The first part of the paper discusses how the biocidal activity of nonwovens is a function of the active agent added to the nonwovens, the duration of the contact of microorganisms with nonwovens and the type of microorganisms. The types of fibres and disinfecting agents had a considerable effect on the biocidal activity of nonwovens. The biocidal effect of nonwovens increased with the duration of their contact with microorganisms. Fibre activity differed considerably depending on the species of the microorganism. The microorganisms most sensitive to biocidal activity of the active filter nonwoven were S. aureus, M. flavus and E. coli. There were no biocidal effects on spore-forming bacterium B. subtilis.

Aspects of tests and assessment of filtering materials used for respiratory protection against bioaerosols. Part II: sweat in the environment, microorganisms in the form of a bioaerosol.

The second part of the article presents the results of a study of antimicrobial activity of filter nonwovens with an addition of biocides, as a function of the presence of sweat in the environment and the method of microbe deposition on a nonwoven in the form of a liquid and a bioaerosol. At the same time, the filtration efficiency of nonwovens against microorganisms in the form of a bioaerosol was tested with the dynamic method. The results showed that the addition of sweat on the surface of a nonwoven resulted in an insignificant decrease of biological activity that still remained high. Moreover, an active nonwoven showed biostatic and biocidal activity only when microbes were deposited on the surface in the form of a solution. The nonwoven did not show any biological activity after deposition of microorganisms with the dynamical method in the form of a bioaerosol.