Nasal Filters Research Articles

Nasal filter reveal exposure risks of inhalable particulates and heavy metals in urban women

Urban populations, especially women, are vunerable to exposure to airborne pollution, particularly inhalable particulates (PM10). Thus, more accurate measurement of PM10 levels and evaluating their health effects is critical for guiding policy to improve human health. Previous studies obtained personal PM10 with time-weighted average by air filter-based sampling (AFS), which ignores individual differences and behavioral patterns. Here, we used nasal filters instead of AFS to obtain actual inhaled PM10 under short-term exposure for urban dwelling women during a severe haze event in Beijing in 2016. The levels of six heavy metals such as As, Cd, Ni, Cr, Pb, and Co in PM10 were investigated, and carcinogenic and non-carcinogenic risks evaluated based on an adjusted US EPA health risk assessment model. The health endpoints for urban dwelling women were further assessed through an exposure-reponse model. We found that the hourly inhaled dose of PM10 obtained through the nasal filter was about 2.5–17.6 times that obtained by AFS, which also resulted in 4.41–11.30 times more morbidity than estimated by AFS (p < 0.05). Proximity to traffic emissions resulted in greater exposure to particulate matter (>18.8 μg/kg·h) and heavy metals (>2.2 ng/kg·h), and these populations are therefore at greatest risk of developing non-cancer (HI = 4.16) and cancer (Rt = 7.8 × 10−3) related morbities.

Re-inventing protection in a post-pandemic world: A new aerodynamic endonasal filtration technology

Is there a “missing device” for respiratory personal protection? Does it exist an easy-to-use device, allowing extensive use in everyday settings by the population, maximizing tolerability and low visual and physical invasiveness protecting from a wide range of threats including airborne pathogens, hence including the particle range of fine and ultrafine particles? Looking at the recent past, in the urgency of finding ready-to-use solutions for the respiratory protection of the population during the outbreak of the SARS-CoV-2 pandemic, devices for occupational safety have been used, such as filtering face masks. These are devices intended for workers operating during work shifts in environments characterized by potential high risk, known a priori, often directly sensible; this makes wearers motivated to tolerate discomfort for a given period to face a localized risk, and safety managers determined to supervise compliance with usage specifications. Their use by general population has implied known shortcomings, such as weak compatibility with relational work and activities, low tolerability during prolonged use, low compliance with the proper use of the device, all of this lessening actual protection. The need for a new perspective has emerged, targeting effectiveness in whole daily life, rather than punctual efficacy. Nasal filters are promising candidates to protect individuals throughout the day during the most varied activities, but they lack a systematic definition as a device and as a product; it follows that the high complexity needed to reach an effective performance envelop is generally underestimated. By reviewing available literature, the present paper draws on the experience from the pandemic and infers systematic product specifications and characterization methods for a new, effective personal respiratory protection device; these specifications are compared with the stringent constraints associated with the endonasal applications and, based on air filtration state of the art, quantifies the need for technology disruption and outlining possible new development paths.

Personalized Nasal Protective Devices: Importance and Perspectives.

Nowadays, in addition to diseases caused by environmental pollution, the importance of personalized protection against various infectious agents has become of paramount importance. Besides medicine, several technical and technological studies have been carried out to develop suitable devices. One such revolutionary solution is the use of personalized nasal filters, which allow our body to defend itself more effectively against external environmental damage and pathogens. These filters are small devices that are placed in the nose and specifically filter the inhaled environmental contaminants, allergens, and microorganisms according to individual needs. These devices not only play a key role in maintaining our health but also contribute to environmental protection, reducing the inhalation of pollutants and their harmful impact on the natural environment. Another advantage of personalized filters is that they also provide an opportunity to strengthen our individual immune systems. The use of personalized filters allows medicine to provide optimized protection for everyone, focusing on individual genetic and immunological conditions. The momentum behind the development and research of personalized nasal filters has reached astonishing proportions today. Nowadays, many research groups and medical institutions are working to create new materials, nanotechnologies, and bioinformatics solutions in order to create even more effective personalized nasal filters that can also be shaped easily and safely. Considering the needs of the users is at least as important during development as the efficiency of the device. These two properties together determine the success of the product. Industry research focuses not only on improving the efficiency of devices, but also on making them more responsive to user needs, comfort, and portability. Based on all this, it can be concluded that personalized nasal filters can be a promising and innovative solution for protection against environmental pollutants and pathogens. Through a commitment to the research and development of technology, the long-term impact of such devices on our health and the environment can be significant, contributing to improving people's quality of life and creating a sustainable future. With unique solutions and continuous research, we give hope that in the future, despite the environmental challenges, we can enjoy the protection of our health with even more efficient and sophisticated devices.

A new aerodynamic endonasal filtration technology for protection against pollutants and respiratory infectious agents: evaluation of the particle filtration efficacy.

An innovative nasal filter was tested, based on aerodynamic air filtration and not on conventional air filtration by means of mesh filters. A custom testing system was designed and three sizes of the filter have been tested vs. monodispersed SiO2 particles sized 5 μm, 1 μm, and 0.5 μm under cycling flow of 6 liters per minute, provided by an artificial lung breather simulating spontaneous breathing. Accelerated testing was implemented, challenging filters with a maximum load of 200 mg per cubic meter. All three filters' sizes showed initial filtration efficiencies above 90% vs. all particles' sizes, decreased to not less than 80% after 30 min of accelerated testing, corresponding to 4.5 days of continuous use at 2 mg challenge, this value being associated with hazardous air conditions in the PSI scale. Results in this study indicate that nasal filters based on aerodynamic air filtration can provide fine and ultrafine filtration, offering protection in day-to-day life from risks associated with pollens, mites, PM, pollutants, and respiratory infectious agents, introducing acceptable respiratory resistance.

Paradigm Shift in Design of Tongue Condoms for Genitals or Anal Foreplay and Oral Intercourse: The Game Changer ApproachPhase four Category

Paradigm Shift in Design of Tongue Condoms for Genitals or Anal Foreplay and Oral Intercourse: The Game Changer ApproachPhase four Category

Operative Protocol for Testing the Efficacy of Nasal Filters in Preventing Airborne Transmission of SARS-CoV-2.

Standardized methods for testing Viral Filtration Efficiency (VFE) of tissues and devices are lacking and few studies are available on aerosolizing, sampling and assessing infectivity of SARS-CoV-2 in controlled laboratory settings. NanoAg-coated endonasal filters appear a promising aid for lowering viable virus inhalation in both adult and younger populations (e.g., adolescents). to provide an adequate method for testing SARS-CoV-2 bioaerosol VFE of bio-gel Ag nanoparticles endonasal filters, by a model system, assessing residual infectivity as cytopathic effect and viral proliferation on in vitro cell cultures. A SARS-CoV-2 aerosol transmission chamber fed by a BLAM aerosol generator produces challenges (from very high viral loads (105 PFU/mL) to lower ones) for endonasal filters positioned in a Y shape sampling port connected to a Biosampler. An aerosol generator, chamber and sampler are contained in a class II cabinet in a BSL3 facility. Residual infectivity is assessed from aliquots of liquid collecting bioaerosol, sampled without and with endonasal filters. Cytopathic effect as plaque formation and viral proliferation assessed by qRT-PCR on Vero E6 cells are determined up to 7 days post inoculum. Each experimental setting is replicated three times and basic statistics are calculated. Efficiency of aerosolization is determined as difference between viral load in the nebulizer and in the Biosampler at the first day of experiment. Efficiency of virus filtration is calculated as RNA viral load ratio in collected bioaerosol with and without endonasal filters at the day of the experiment. Presence of infectious virus is assessed by plaque forming unit assay and RNA viral load variations. A procedure and apparatus for assessing SARS-CoV-2 VFE for endonasal filters is proposed. The apparatus can be implemented for more sophisticated studies on contaminated aerosols.

Can nasal filters be used to reduce personal exposure against nano- to submicron-sized environmental tobacco smoke (ETS) aerosols?

Can nasal filters be used to reduce personal exposure against nano- to submicron-sized environmental tobacco smoke (ETS) aerosols?

Use of nasal filters for allergen exposure measurements in veterinary practices

Use of nasal filters for allergen exposure measurements in veterinary practices

Performance of a new model of nasal filter when challenged against PM1 aerosols

ABSTRACT Nasal filters are increasingly used in reducing personal haze exposures, but there is no retrievable evidence on its efficiency. In this study, a nasal filter testing system was designed. NaCl aerosols were generated to simulate PM1. Three different sizes of a new model of nasal filter were tested under two flow types (constant vs. cyclic) and three flow rates (15, 30, and 50 L/min). All PM1 penetration values were > 80%. Either enlarging filter size or lowering flow rate significantly reduced PM1 penetration, and PM1 penetration under cyclic flow was significantly higher compared with constant flow. To avoid mouth breathing, nasal filters could only be worn under light work-rates or rest conditions. The quality factor of nasal filters was only hundredths that of the N95 and P100 FFRs. This study reveals that there is a future need to design nasal filter materials with higher efficiency and lower flow resistance.

Evaluation of the upper airway microbiome and immune response with nasal epithelial lining fluid absorption and nasal washes

Despite being commonly used to collect upper airway epithelial lining fluid, nasal washes are poorly reproducible, not suitable for serial sampling, and limited by a dilution effect. In contrast, nasal filters lack these limitations and are an attractive alternative. To examine whether nasal filters are superior to nasal washes as a sampling method for the characterization of the upper airway microbiome and immune response, we collected paired nasal filters and washes from a group of 40 healthy children and adults. To characterize the upper airway microbiome, we used 16S ribosomal RNA and shotgun metagenomic sequencing. To characterize the immune response, we measured total protein using a BCA assay and 53 immune mediators using multiplex magnetic bead-based assays. We conducted statistical analyses to compare common microbial ecology indices and immune-mediator median fluorescence intensities (MFIs) between sample types. In general, nasal filters were more likely to pass quality control in both children and adults. There were no significant differences in microbiome community richness, α-diversity, or structure between pediatric samples types; however, these were all highly dissimilar between adult sample types. In addition, there were significant differences in the abundance of amplicon sequence variants between sample types in children and adults. In adults, total proteins were significantly higher in nasal filters than nasal washes; consequently, the immune-mediator MFIs were not well detected in nasal washes. Based on better quality control sequencing metrics and higher immunoassay sensitivity, our results suggest that nasal filters are a superior sampling method to characterize the upper airway microbiome and immune response in both children and adults.

Utility of Environmental Exposure Unit Challenge Protocols for the Study of Allergic Rhinitis Therapies.

This paper explores how the Environmental Exposure Unit (EEU) experimental model can be used to further our understanding of pharmacotherapies and immunotherapies for the treatment of allergic rhinitis (AR). EEUs are used increasingly for the study of combination therapies, immunotherapies, and novel AR treatments. A combined antihistamine/corticosteroid nasal spray formulation was seen to have a faster onset of action relative to the therapies individually in the Environmental Exposure Chamber. House dust mite sublingual immunotherapy tablets are both safe and efficacious as evaluated by the Vienna Challenge Chamber. The Kingston EEU found that a novel peptide-based immunotherapy approach to be effective in reducing grass pollen-induced AR. Lastly, nasal filters were determined to reduce seasonal AR symptoms, given out-of-season in the Denmark Environmental Exposure Unit. EEUs are controlled, replicable models that provide valuable insight into the efficacy, onset and duration of action, and dose-related impacts of AR therapeutics, with direct clinical relevance.

Enhanced Capture of Particulate Matter by Molecularly Charged Electrospun Nanofibers

We introduce molecularly charged electrospun nanofibers obtained by soft chemical treatment for the capture of particulate matter (PM). These PMs, along with certain volatile organic compounds (VOCs), pose a severe threat not only to human health but also to the environment. As the concentrations of these PMs have been steadily increasing in the Southeast Asian countries, a dire need for protection against these particles is warranted. Filtering out the polluted air using various filtration media, such as face masks and nasal filters, has been the standard method for minimizing exposure to PM. Here, we demonstrate the removal of PM and VOCs by utilizing electrospun nanofibers of polystyrene (PS) and polyacrylonitrile (PAN) with molecular charges imparted on them via chemical treatment. The chemically treated fibers were successful in capturing even particles measuring 300 nm, which are considered to be the most penetrable particles. We report a filtration efficiency of ∼93% for removing such particles, which is ∼3 ± 1.5% enhancement when compared to the untreated fibers. The fibers have been subjected to extreme haze conditions (∼1413 μg m–³) of PM₂.₅ for a duration of 1 h, and the filtration efficiency was measured to be ∼99.01%. These fibers also possess the capability to capture model VOCs such as aniline, toluene, tetrahydrofuran, and chloroform. When PAN, PS, and their chemically treated counterparts were tested for their antibacterial activity, these filter mats had bactericidal effect on Escherichia coli, Bacillus subtilis, and Enterococcus faecalis. A nasal plug hosting these filter mats has been designed, which can offer personal protection from PM. Enhanced removal of residual particles is extremely important, and this difficult task is made possible with our approach. The efficiency of our approach is due to the charged nature of PM, especially of the smaller size regime.

Effectiveness of a portable air filtration device in reducing allergen exposure during household chores

Exposure to airborne allergens is an important risk factor for sensitization, allergic rhinitis and asthma. The aim of this study is to verify whether the use of an air filtration device, called “air purifier” (AP) is able to reduce indoor allergen exposure. In three rooms of one household with pets (a cat and a dog), inhalable dust was sampled with transportable pumps for 1–2 h during typical household chores on 15 days—either in the morning without the AP or in the afternoon using an AP. In addition to sampling inhalable dust both with a stationary and a personally carried pump with Teflon filters, nasal filters were used. Inhalable dust on the Teflon filters was quantified gravimetrically, and allergen content was measured on all filters (n = 90) using fluorescence enzyme immunoassays for domestic mites (DM), the cat allergen Fel d 1, and the dog allergen Can f 1. The use of the AP significantly reduced inhalable dust in both personal and stationary samples by 40 or 20%, respectively. In most cases, allergen exposure was also reduced; the median allergen concentrations in the air were up to 60% lower with the AP than without. Allergen exposure varied greatly, and with the exception of Can f 1 sampled with the personally carried pump, and DM allergens in the nasal samples, there was no significant difference with or without an AP. Typical household chores can result in high levels of exposure to indoor dust and allergens. The use of an AP however can reduce the inhalable dust concentrations, but the effect on allergen exposure was in most cases not large enough to achieve statistical significance.

The Long-Term Algae Extract (Chlorella and Fucus sp) and Aminosulphurate Supplementation Modulate SOD-1 Activity and Decrease Heavy Metals (Hg++, Sn) Levels in Patients with Long-Term Dental Titanium Implants and Amalgam Fillings Restorations.

The toxicity of heavy metals such as Hg++ is a serious risk for human health. We evaluated whether 90 days of nutritional supplementation (d90, n = 16) with Chlorella vulgaris (CV) and Fucus sp extracts in conjunction with aminosulphurate (nutraceuticals) supplementation could detox heavy metal levels in patients with long-term titanium dental implants (average: three, average: 12 years in mouth) and/or amalgam fillings (average: four, average: 15 years) compared to baseline levels (d0: before any supplementation, n = 16) and untreated controls (without dental materials) of similar age (control, n = 21). In this study, we compared levels of several heavy metals/oligoelements in these patients after 90 days (n = 16) of nutritional supplementation with CV and aminozuphrates extract with their own baseline levels (d0, n = 16) and untreated controls (n = 21); 16 patients averaging 44 age years old with long-term dental amalgams and titanium implants for at least 10 years (average: 12 years) were recruited, as well as 21 non-supplemented controls (without dental materials) of similar age. The following heavy metals were quantified in hair samples as index of chronic heavy metal exposure before and after 90 days supplementation using inductively coupled plasma-mass spectrometry (ICP-MS) and expressed as μg/g of hair (Al, Hg++, Ba, Ag, Sb, As, Be, Bi, Cd, Pb, Pt, Tl, Th, U, Ni, Sn, and Ti). We also measured several oligoelements (Ca++, Mg++, Na+, K+, Cu++, Zn++, Mn++, Cr, V, Mo, B, I, P, Se, Sr, P, Co, Fe++, Ge, Rb, and Zr). The algae and nutraceutical supplementation during 90 consecutive days decreased Hg++, Ag, Sn, and Pb at 90 days as compared to baseline levels. The mercury levels at 90 days decreased as compared with the untreated controls. The supplementation contributed to reducing heavy metal levels. There were increased lithium (Li) and germanium (Ge) levels after supplementation in patients with long-term dental titanium implants and amalgams. They also (d90) increased manganesum (Mn++), phosphorum (P), and iron (Fe++) levels as compared with their own basal levels (d0) and the untreated controls. Finally, decreased SuperOxide Dismutase-1 (SOD-1) activity (saliva) was observed after 90 days of supplementation as compared with basal levels (before any supplementation, d0), suggesting antioxidant effects. Conversely, we detected increased SOD-1 activity after 90 days as compared with untreated controls. This SOD-1 regulation could induce antioxidant effects in these patients. The long-term treatment with algae extract and aminosulphurates for 90 consecutive days decreased certain heavy metal levels (Hg++, Ag, Sn, Pb, and U) as compared with basal levels. However, Hg++ and Sn reductions were observed after 90 days as compared with untreated controls (without dental materials). The dental amalgam restoration using activated nasal filters in conjunction with long-term nutritional supplementation enhanced heavy metals removal. Finally, the long-term supplementation with these algae and aminoazuphrates was safe and non-toxic in patients. These supplements prevented certain deficits in oligoelements without affecting their Na+/K+ ratios after long-term nutraceutical supplementation.

Lower allergen levels in hypoallergenic Curly Horses? A comparison among breeds by measurements of horse allergens in hair and air samples.

BackgroundExposure to horses can cause severe allergic reactions in sensitized individuals. The breed, American Bashkir Curly Horse is categorized as hypoallergenic, primarily due to reports of allergic patients experiencing fewer symptoms while handling this special breed. The possible reasons for this phenomenon could be lower allergen production and/or reduced allergen release into the air because of increased sebum content in their skin and hair compared to other breeds. Therefore, the aim of the current study was to compare different horse breeds in relation to allergen content in hair and airborne dust samples.MethodsIn total, 224 hair samples from 32 different horse breeds were investigated. Personal nasal filters were used to collect airborne dust during the grooming of 20 Curly Horses and 20 Quarter Horses. Quantitative analysis of all samples was performed using two newly developed immunoassays for the detection of horse dander (HD) antigens and the major allergen Equ c 1 and the commercial assay for Equ c 4. Results were analyzed using multiple linear regression models for hair samples and the Mann Whitney U test for airborne samples.ResultsHorse antigen and allergen levels differed up to four orders of magnitude between individual animals. Despite enormous variability, levels of HD antigen, Equ c 1 and Equ c 4 in hair were significantly related to the breed and gender combined with the castration status of male animals. Curly Horses had significantly higher concentrations of all three tested parameters compared to the majority of the investigated breeds (medians: 11800 μg/g for HD antigen, 2400 μg/g for Equ c 1, and 258 kU/g for Equ c 4). Tinker Horses, Icelandic Horses and Shetland Ponies were associated with approximately 7-fold reduced levels of HD antigen and Equ c 1, and up to 25-fold reduced levels of Equ c 4 compared to Curly Horses. Compared to mares, stallions displayed increased concentrations of HD antigens, Equ c 1 and Equ c 4 by a factor 2.2, 3.5 and 6.7, respectively. No difference was observed between mares and geldings. No differences in airborne allergen concentrations collected with personal nasal filters during grooming were found between Curly and Quarter Horses.ConclusionBreed and castration status had a significant influence on the antigen and allergen levels of horse hair. However, these differences were smaller than the wide variability observed among individual horses. Compared to other breeds, Curly Horses were not associated with lower allergen levels in hair and in air samples collected during grooming. Our approach provides no molecular explanation why Curly Horses are considered to be hypoallergenic.

Design and Development of a Novel Nanofiber Nasal Filter (NNF) to Improve Respiratory Health

Currently available nasal filters are not well-suited for protecting humans against the fine and ultrafine airborne particles. In this research, we designed and evaluated a novel nanofiber nasal filter (NNF) capable of reducing personal exposure not only to large allergenic particles but also to ultrafine particles, thus reducing respiratory health risks. A new hybrid filter (HF) medium for the NNF was fabricated by overlaying a carbon filter substrate with nylon nanofibers produced by electrospinning. After optimizing the filter’s production parameters, the HF was produced using the Nylon-6 polymer solution with a concentration of 15 wt%, a substrate based on a MERV 5 carbon filter with a density of 61 kg m–3, and a nanofiber surface coating density of 0.72 g m–2 (or 0.54 g m–2 as a second choice). The new HF was tested with fluorescent polystyrene latex beads sized 0.026–3.1 µm and at operating flow rates of 7.5–30 L min–1. The newly developed NNF showed more than a 90% collection efficiency for particles > 1 µm, representing bacteria and molds, and more than a 50% efficiency for particles < 0.5 µm, including ultrafine particles—about a 2.3-fold improvement compared to commercially available nasal filters. Thus, this NNF may serve as a useful tool to minimize our exposure to airborne pollutants.

Clinical efficacy of Dobronos nasal filters in complex allergic rhinitis therapy

Allergic rhinitis (AR) is a wide spread chronic respiratory disease requiring prolonged anti-inflammatory treatment. AR exacerbations follow the contact with allergen / allergens. We evaluate nasal filters efficacy in complex AR of mild and moderate severity therapy in patients with house dust and animal dander sensitization. 6-week open study included 50 patients 5 to 42 years old. The study included 2-week enrollment and 4-week treatment periods. 46 patients completed the treatment period, 3 were excluded due to nasal discomfort during filter use, and one patient due to non-compliance. In mild AR patients we revealed significant reduction in all AR symptoms according to the TNSS scale. In moderate AR patients we found significant reduction in nasal itch and sneezing only. In comparison with the enrollment period, the number of days with as-needed antihistamine intake reduced and the number of symptom-free days increased significantly in both mild and moderate AR groups. Nasal protective filters can be recommended for complex therapy in mild and moderate AR in most patients.

Clinical Application of Nasal Filters: An Observational Study on the Usability of Nasal Filters in Managing Seasonal Allergic Rhinitis

A recent park study found a substantial preventive effect of a new nasal filter for seasonal allergic rhinitis. However, the nasal filter still needs to prove that it is sufficiently convenient and comfortable for everyday use during a regular pollen season. The objective of this study was to evaluate the usability of the nasal filter (Rhinix, Rhinix ApS, Aarhus, Denmark) in a large population. An observational, open-label study (NCT02108379) conducted during the main grass pollen season in 2014 in Denmark included 1073 participants with seasonal allergic rhinitis, with or without asthma. Participants received the filters for a 2-week use period. Identical online questionnaires were answered after each week of use. End points included ratings on satisfaction, usage, and interest in continued use, stratified by allergy and asthma severity. There were 834 filter users in week 1; 634 of these continued use in week 2. After week 1, 630 (76%) expressed interest in continued use of the filters. Participants who continued use in week 2 had higher screening scores for nasal symptoms (P= .01), had more severe asthma for those with asthma (P= .04), and were more dissatisfied with their usual treatment compared with the participants who discontinued use (P= .03). Of 834 new users, 630 stated interest in continued use of the filters. On the basis of the findings of this large observational usability study, the nasal filters appear sufficiently convenient and comfortable to use and thus clinically relevant for symptom management for many allergy sufferers.

Preventive effect of nasal filters on allergic rhinitis: A randomized, double-blind, placebo-controlled crossover park study

A recently reported small, out-of-season environmental exposure unit study found nasal filters to be efficacious in preventing seasonal allergic rhinitis (AR). However, nasal filters still need to show efficacy in a natural setting in a regular pollen season. We sought to evaluate the efficacy of nasal filters (Rhinix; Rhinix ApS, Aarhus, Denmark) for the prevention of symptoms related to seasonal AR. The trial was a single-center, randomized (1:1), double-blind, placebo-controlled crossover clinical trial (NCT02108574) conducted over 2 days in the main grass pollen season in June 2014 in Aarhus, Denmark, on 65 adults with proven grass allergy. A total nasal symptom score (TNSS) consisting of blocked nose, runny nose, nasal itching, and sneezing was used to evaluate symptoms. The difference in daily∑ TNSS (the sum of 13 ratings) was the primary outcome measure. The difference in maximum TNSS (highest score, 13 ratings) was also evaluated. The nasal filters significantly reduced daily∑ TNSSs (P = .03) and maximum TNSSs (P = .03) compared with placebo. Median relative reductions were 40% for daily∑ TNSSs (P = .02), 43% for maximum TNSSs (P = .004), 83% for daily∑ sneezing (P = .001), 75% for daily∑ watery eyes (P = .02), and 53% for daily∑ runny nose (P = .005) when compared with placebo. The nasal filters were well tolerated, and no serious adverse events were recorded. Statistically significant and clinically relevant reductions were achieved for the primary outcome measure of daily∑ TNSS, for maximum TNSS and for a subset of individual symptoms. The results support the preventive role of nasal filters for managing seasonal AR.

Nasal filters for the treatment of allergic rhinitis: A randomized, double-blind, placebo-controlled crossover clinical trial

Nasal filters for the treatment of allergic rhinitis: A randomized, double-blind, placebo-controlled crossover clinical trial