EFFICIENCY OF RESPIRATORY PROTECTION DEVICES AGAINST BIRD FLU VIRUS

Transcription

1 EFFICIENCY OF RESPIRATORY PROTECTION DEVICES AGAINST BIRD FLU VIRUS ŽELJKO SENIĆ Military Technical Institute, Belgrade, MARINA ILIĆ Military Technical Institute, Belgrade, ANTON RADOJKOVIĆ Military Technical Institute, Belgrade, DUŠAN RAJIĆ Military Technical Institute, Belgrade, RADOVAN KARKALIĆ Technical Testing Center, Belgrade, Abstract: This study presents efficiency of different protection devices against the effects of the bird flu virus. Laboratory results of determining the efficiency of respiratory protection devices are presented. Comparative study of efficiency of different nanomaterials has been carried out and the suggestions for improvement of the protection level of the respiratory devices in regards to the bird flu have been given. Key words: virus, bird flu, protection efficiency, respiratory devices, nanomaterials. 1. INTRODUCTION World population of today is in great danger of various diseases spread. The World Health Organization, (WHO) has announced the possibility of different pandemic forms. Only in last century there were 3 influenza pandemics [1]: Spanish influenza, virus subtype А (H1N1), around 20 million people died Asian influenza, virus subtype А (H2N2), 1968 Chinese (Hong Kong) influenza, virus subtype А (H3N2) Real pandemic danger, virus subtype А (H5N1 and H9N2). Source of infection was poultry. Pandemic was avoided due to the absence of inter human virus transfer Mexican or Swine influenza, А (H1N1). In the last decade there has not been any pandemic with high mortality rate, despite some predictions. However, the probability of pandemic emerging with many casualties is very real, so it is necessary to provide adequate protection for the population. Most respiratory protection devices which are used by armies worldwide are very effective for the biological agents protection. Respiratory protection devices available to the civilian populations are half masks, surgery masks and epidemiological masks. Best protection is ensured with epidemiological nanomasks. Military Technical Institute in cooperation with company ''9 th September'', from Gornji Milanovac, has developed and produced new epidemiological mask. This study shows testing results of epidemiological masks and analysis of efficiency of protection against viruses. 2. BIRD FLU Avian virus (Bird flu) first appeared in Italy 100 years ago [2]. During the twentieth century there were several local infections caused by different variants of the avian virus. In the last eight years, disease frequently appeared in Asia, but in 2003 there was a local disease in Europe. Even though there were few weird cases of disease spread in Thailand and Vietnam, for now, the bird flu virus is not transmitted from human to human, which is proved by the genetic analysis which have been conducted so far. However, Avian virus (Picture 1) can be transmitted from birds to humans. 592

2 Respirators (semi masks) protection from radioactive dust or industry or mines dusts. Disposable masks (surgical and epidemical masks) protection from dust in industry, biological agents(bacteria, viruses etc.) in medicine. For civilian use there are some very effective respirators and disposable masks. Quality of those devices depends on type and quality, i.e. the class of particle filter. (Picture 2). Picture 1: Avian (Bird flu) virus - enlarged times The transmission process starts with birds expelling virus through their faces for 10 days. Then it dries, hardens and turns into dust, thus the virus is gets into an organism by being inhaled. Bird meat and eggs are not contagious, thus it is highly unlikely for someone to get infected as a result of eating poultry or eggs. Virus can be easily destroyed by temperatures over 80 C, but it is very resistant to freezing, being able to survive the temperature as low as 270 C. For now, avian influenza can only be transmitted from birds to humans, but many experts believe that there is a chance of pandemic, if the virus mutates. When a person, who was in contact with infected birds, simultaneously gets infected by both, bird and human flu, there is a chance of gene exchange between the two viruses in human body. This new virus then can be transmitted among humans and with the probability of it increases with the number of people who are double infected. 3. BIRD FLU RESPIRATORY PROTECTION DEVICES 3.1. General statements Respiratory protection devices are divided in two functional types: filtrating and isolating type. Filtrating respiratory protection devices use environmental air purified by filters for breathing, while isolating respiratory devices use oxygen bottles or other breathing air sources. [3] Filtrating protection masks are structurally simpler, fo a less weigh, and smaller dimensions in comparison to isolating mask and that is why they are basic respiratory protection device. Protection masks can be [4]: Military protection masks protection of respiratory organs, face and eyes against CWA, biological agents and radioactive aerosols. Industry protection masks protection from toxic gases and vapors in industry facilities, mines, etc. Picture 2: Particle filter Particle filters ( filters for protection against particles) are classified by its ability to retain particles in filter classes 1, 2 and 3 (Table 1, 2 and Picture 3) [4]. They are marked by letter R ( P in cyrilic), filter class and white colour. The coulour for marking is seen in filter enclosures painted in white or the ring painted in white which is on the neutrally painted filter enclosure. The higher filter class includes the possibility of filtrating the lower filter classes for particles. [5]. Table 1: Particle filter classes Particle filter Filtration Protection classes capabilities P1 Solid particles low Solid and liquid P2 medium particles Solid and liquid P3 high particles Table 2: Semi mask classification CLASS Allowed total leakage (%) Max breathing resistance allowance(pa) FFP FFP FFP Particle filters are by rule made of natural or artificial fibers. Particle filters filter (clean, purify) air from particles (floating materials and aerosols, dust, smoke, fog, etc.), which depending on the filtrating power divide at different quantities. 593

3 New research involves titanium oxide nanoparticles in filters. As nanomask construction is concerned, there are two types of it: one-part and two-part masks(picture 4a and 4b) One-part nanomasks have particle filter with one layer of nanoparticles. Wearing time is limited to 6-8 hours. Two-part masks are suitable for multiple uses. Two-part nanomasks have two filters, one for particles and other with nanoparticles. [7]. Company 9 th September from Gornji Milanovac has developed one-part nanomask which is tested in Military Technical Institute laboratories. Tests are performed in accordance with SRPS EN 149:2007 part 8.5 and SRPS EN 14:2007 part 8.7. Picture 3: Particle filter classes and filtration efficiency Filters of the P1 filter class may be used only for inert particles protection. Inert particles are non-toxic chemicals which cannot harm respiratory organs. Also particles with less than 1% of quartz in mass are considered inert. Filters of the P3 filter class are used for micron size (hazardous material) particles. P3 filters are also in use for protection from radioactive particles and viruses. Biological aerosol particles may vary in size: viruses from 0,003 to 0,05 µm, and bacteria from 0,3 to 30 µm [6] Nanomasks Disposable masks (surgical and epidemic masks, the so called nanomasks ) have ben used over the last ten years mostly by civilian population for protection against viruses. Surgical mask have provided partial, but not full protection. With nanotechnology development, production of nanomasks for protection against viruses started and it had in its particle filters a certain quantity of nanoparticles. Nanomasks have filters for nanoparticles that are very efficient in viruses and bacteria protection. Nanoparticles increase inner filtration efficiency and also have hazardous impact on viruses and bacteria. Most commonly used nanoparticles used in filters are silver oxide nanoparticles. Silver oxide nanoparticles can destroy more than 650 types of viruses, fungus and bacteria in 6 minutes from the contact. 4. EXPERIMENT 4.1. Testing apparatus Inner leaking sodium chloride test is performed on apparatus shown on Picture 5 and its main parts are [5] [8]: а) Aerosol generator Generated aerosol concentration (sodium chloride) in the testing chamber (5) must be homogeneous. Sodium chloride aerosol is generated from 2% (mass) sodium chloride water solution. Sodium sodium-chloride aerosol, a big Collison type generator is used at a pressure of 7 bar or other type of aerosol generator that meets the requirements described in 6.2.b above). The total flow of air with particles of sodium chloride required for the test chamber is 100 dm 3 /min. If the aerosol particles are not well dried it is necessary to remove moisture by the air heating process. b) Sodium chloride aerosol Average concentration value in the testing chamber must be in range of (8 ± 4) mg/m 3. Granulometric distribution must include particles with aerodynamic diameter between μm, with average diameter by weight of 0.6 μm. c) Flame photometer Flame photometer is used for sodium chloride aerosol concentration determination. Main properties of flame photometer must include: possibility for direct aerosol concentration determination, possibility for determination of aerosol in concentration range of 0,5 ng/m 3 to 15 mg/m 3, total aerosol sample flow of sodium chloride needed for determination of the concentration trough the flame photometer must not exceed 15 dm 3 /min, response time must be less than 500 ms; а Picture 4: Nanomasks б 594

4 4.4. Calculation of leakage Inner leakage (P) is calculated from aerosol concentration average values in last 100 seconds of every test session. Inner leakage (Р) expressed in percentage is calculated with the formula (1): Picture 5: Sodium chloride inner leakage test apparatus 1 Aerosol generator (Atomizer) 2 Pump 3 Valve for sample selection 4 Air filtration filter 5 Testing chamber 6 Aerosol sample from testing chamber C о 7 Aerosol sample under the mask C m 8 Pressure sensor 9 Flame photometer 10 Universal filter simulator 11 Treadmill 12 Aerosol inlet 13 Extra air for aerosol dilution 14 Sampling impulse interface d) Sampling probe Sampling probe must be implemented into the mask and must be well sealed. Also, anti-condensation measures must be performed (dry air introduction). Sampling probe must not touch lips and must not disturb normal breathing process Operating principle Examinee with protection mask walks on treadmill and above his head must be special chamber. Through this chamber constant NaCl aerosol flows. Samples of the air under the mask are taken during the breathing phase. Samples are taken with the sampling probe Testing process Testing process: Examinee with mask without filter enters the testing chamber and walks for 2 minutes on treadmill at the speed of 6 km/h. After 2 minutes aerosol concentration is determined. Determination of aerosol concentration is being done until the constant value is determined. Examinee keeps walking another 2min or until reaching equilibrium values of concentration of sodium chloride aerosol; Examinee performs following tasks during the walk: walking, head turning left right (15 times), head moving up and down (15 times), saying the alphabet (or other text). Monitoring of aerosol concentration in the chamber Cm t in + tex P (%) = 100 (1) Co tin C m NaCl aerosol concentration under the mask, determined in the inhalation phase (mg/m 3 ); C o average NaCl aerosol value in the testing chamber (mg/m 3 ); t in t ex 5. RESULTS overall inhalation time (s); overall exhalation (s) Testing samples During the Bird flu epidemic company 9th September, Gornji Milanovac, start to develop new one-part mask with nanomaterial. Nanomaterial was fiberglass type (manufactured by company LYDAIR). Different models of nanomasks (semi-masks) were produced from that nanomaterial Testing results Testing result of nano semi-masks are shown in Table 3. Table 3: Tested semi-masks classification in accordance with SRPS EN 149:2007 No. Sample number Resistance to the airflow of 30 L/min (Pa) Average NaCl aerosol leakage (%) Class in accordance to SRPS EN 149/ FFP FFP ,4 FFP ,3 FFP ,9 FFP ,7 FFP ,6 FFP ,2 FFP ,5 FFP ,9 FFP Discussion Best results of all tested mask, in accordance to the SRPS EN 149:2007, were masks with the sample numbers: 1. For class FFP1 - sample number 10311, 2. For class FFP2 - sample number and 3. For class FFP3 - sample number Samples are structurally similar, so that results are similar 595

5 too. All samples are homogenous and it is good characteristic for semi-masks. Airflow resistance for all masks are is in accordance with requirements given SRPS EN 149:2007 part Based on presented results, conclusion is that company 9th September was successfully developed new nano semi-masks classes FFP1, FFP2 and FFP3 in accordance with European standard SRPS EN 149:2007. Semi-mask model with sample number is the only class FFP3 mask model and only suitable for Bird flu virus protection. 6. CONCLUSION In the last ten years there has not been any pandemics with high mortality, but the likelihood of a pandemic and the threat to public health is not decreased so, it is necessary to provide adequate protection to citizens in case of any of its occurrence.. Nanomasks class FFP3 is very effective in providing protection against Avian virus (Bird flu virus) and other similar viruses. Nanomask wearing time is limited and depends on nanomask quality, but must not exceed 8 hours. The effectiveness of nanomask depends a lot on the proper use of masks (masks-fixing). Company 9 th September has proved that is capable of developing and producing effective nanomask class FFP1, FFP2 and FFP3 in accordance with European standard SRPS EN 149:2007. ACKNOWLEGDEMENT The publishing of this paper has been supported through material and financial help of the Ministry of Education and Science within the project TR 34034, to which the authors are deeply grateful. REFERENCES [1] Ortrud, W., Harder, T. C., Bird Flu, [2] Veselinovic, M., BIRD FLU A/H5N1, Review article, publisher.medfak.ni.ac.rs/2007- html/3.../pticiji%20grip%20ah5n1.pdf [3] EN 132: 1998, Respiratory Protective Devices - Definitions of Terms and Pictograms. [4] EN 134: 1998, Respiratory Protective Devices - Nomenclature of Components. [5] SRPS EN 149:2007 Respiratory Protective Devices Filtering Half Mask to Protect Against Requirements, Testing, Marking [6] Lazarevic, N., Filipovic, M., Jevremovic, M., Nesesery Assessment of Respiratory Protection Required in Relation to Radioactive Aerosols, Military Technical Institute , Belgrade, [7] [8] SRPS 8746: 2005, Personal Respiratory Protection Devices, Protective mask, Testing methods. 596