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Negative ion reaction equations

Negative air ions (NAI) are important air component, generally referring to the collections of negatively charged single gas molecules or ion clusters in the air. They play an essential role in maintaining the charge balance of the atmosphere.[1][2] The main components of air are nitrogen and oxides. Due to the strong electronegativity of oxygen and other molecules, they can easily capture free electrons to form negatively charged air ions, most of which are superoxide radicals ·O2−,so NAI is mainly composed of negative oxygen ions, also called air negative oxygen ions.[3]

Research history

In 1889, German scientists Elster and Geitel first discovered the existence of negative oxygen ions.[4][5]

At the end of the 19th century, German physicist Philipp Eduard Anton Lenard first explained the effects of negative oxygen ions on the human body in academic research.

In 1902, scholars such as Ashkinas and Caspari further confirmed the biological significance of negative oxygen ions. In 1932, the world's first medical negative oxygen ions generator was invented in the United States.[6]

In the middle of the 20th century, Professor Albert P. Krueger of the University of California, Berkeley,conducted pioneering research and experiments on the biological effects of ions at the microscopic level. Professor Krueger demonstrated the impact of negative oxygen ions on humans, animals, and plants from the aspects of biological endocrine, internal circulation, and the generation reactions of various enzymes through a large number of animal and plants experiments.[7][8][9]

From the end of the 20th century to the beginning of the 21st century, many experts, scholars, and professional medical institutions applied negative ions (negative oxygen ions) technology to clinical practice. Through various explorations, new ways of treating diseases were opened up.[10][11][12][13][14]

In 2011, the official website of the China Air Negative Ion (Negative Oxygen Ion) and Ozone Research Society was launched. This website is the first negative ions industry website in China, and its purpose is to rapidly promote the orderly development of the air negative ion (negative oxygen ion) industry.

In 2020, the Tianjin Advanced Manufacturing Research and Development Center of Tsinghua University successfully developed a medical-grade high-concentration negative oxygen ion generator. It only needs to be sprayed on the room's walls to form a uniform and dense layer of nanoparticles on the wall, allowing the indoor wall to stably and long-term release high-concentration small-particle negative oxygen ions.[15]

Generation mechanism

Common gases that produce negative air ions include single-component gases such as nitrogen, oxygen, carbon dioxide, water vapor, rare gases, or multi-component gases obtained by mixing these single-component gases. Various negative air ions are formed by combining active neutral molecules and electrons in the gas through a series of ion-molecule reactions.[16]

In the air, due to the presence of many water molecules, the negative air ions formed are easy to combine with water to form hydrated negative air ions, which are typical negative air ions, such as O-·(H2O)n, O2-·(H2O)n, O3-·(H2O)n, OH-·(H2O)n, CO3-·(H2O)n, HCO3-·(H2O)n, CO4-·(H2O)n, NO2-·(H2O)n, NO3-·(H2O)n,etc.[17][18][19][20] The ion clusters formed by the combination of small ions and water molecules have a longer survival period due to their large volume and the fact that the charge is protected by water molecules and is not easy to transfer. This is because in the molecular collision, the larger the molecular volume, the less energy is lost when encountering collisions with other molecules, thereby extending the survival time of negative air ions.[21][22]

Generation methods

Negative air ions can be produced by two methods: natural or artificial.The methods of producing negative air ions in nature include the waterfall effect, lightning ionization, plants tip discharge, etc. Natural methods can produce a large number of fresh negative air ions. The artificial means of producing negative air ions include corona discharge, ultraviolet irradiation, and other methods.[23] Compared with the negative air ions produced in nature, although artificial methods can produce high levels of negative air ions, there are specific differences in the types and concentrations of negative air ions, which makes the negative air ions produced by artificial methods may not achieve the excellent environmental health effects of negative air ions produced in nature.[24] Improving the artificial method to produce ecological-level negative ions is necessary.

Natural environments

  • Waterfall method : When people are in a water-rich environment such as a waterfall, fountain, or seaside, they usually feel relaxed and release of stress, which is related to many negative air ions in the environment. As one of the most common methods for producing negative air ions in nature, the scope of the waterfall method is not limited to the surrounding areas of waterfalls. Rainfall, lake ripples, city fountains, etc., can also cause charge redistribution.[25][26]
The Leonard Effect
The mechanism of producing negative air ions by the waterfall method was first discovered by German scientist Lenard in 1915. The Lenard effect is achieved through two methods: the rupture of the "ring-bag" structure and the local protrusion separation.[27][28] The "ring-bag" structure rupture theory believes that during the collision between water and gas, the water droplets will form a "U"-shaped intermediate with a "ring-bag" structure when subjected to external impact. The intermediate will then break apart to form small droplets with negative charges and large droplets with positive charges. The local protrusion separation theory believes that when water droplets collide with each other or are subjected to external forces, the water droplets will automatically protrude locally and generate negative charge aggregation. When subjected to shear force, this part will form negative ions with crystal water and be released into the air.[29][30][31]
  • Lightning strike method : The atmosphere itself is a huge electric field. Positive and negative charges will accumulate above and below the clouds. When the droplets in the clouds continue to accumulate and gradually approach the ground due to gravity, a giant capacitor will be formed between the clouds and the ground. When the electric field strength between the two exceeds the dielectric strength of the air, discharge will occur and break through the air.[32] During the lightning discharge process, charged particles bombard the surrounding air molecules, ionizing the molecules to generate negative air ions. At the moment of the lightning strike, hundreds of millions of negative air ions will be generated.[33] This is why people feel the air is fresh and clean after rain. It is not only because the rain increases the humidity of the air, but more importantly, the concentration of negative ions in the air has increased significantly. The lightning strike method is one of the most important methods of providing negative air ions in nature.[34][35]
The tip of the leaves of vegetation will discharge under the action of the photoelectric effect, which can ionize nearby air molecules under the action of the atmospheric electric field. Like the corona discharge, the needle tip will continue to ionize and release negative air ions. In addition, the reason why negative air ions can maintain a high concentration for a long time in forests and some areas covered by green vegetation is that the oxygen concentration released by vegetation during photosynthesis is much higher than that in cities, and a large amount of water vapor is released through respiration and leaf transpiration. Oxygen and water vapor can produce free electrons under ionization. Due to their strong electronegativity, water molecules and oxygen molecules can easily capture free electrons to form negative air ions.[37]

Artificial ionization

  • Corona discharge method : Currently, the most common artificial method uses corona discharge to generate negative ions. The specific process of the corona discharge method to produce gaseous negative ions is to connect the high-voltage negative electrode to a skinny needle-shaped wire or a conductor with a minimal radius of curvature so that a strong electric field will be generated near the electrode to release high-speed electrons. Its speed is enough to drive the electrons to collide with gas molecules, further ionizing to generate new free electrons and positive ions. The newly generated free electrons will repeat the previous process and continue to collide and ionize to generate new negative air ions. This process will be repeated many times. In the area near the electrode, positive ions and negative ions with the same charge will be evenly distributed. Due to the interaction between charges, ions with positive charges will migrate to the negative electrode so that the negative ions in the local space will be relatively excessive at a certain moment. And the mutual repulsion of same charges, negative air ions will diffuse to the surroundings so that negative air ions are continuously released from the tip electrode.[38][39]

Determination method

Detection of negative air ions is divided into measurement and identification. NAI measurement can be achieved by measuring the change in atmospheric conductivity when NAI passes through a conductive tube. NAI identification is generally achieved using mass spectrometry, which can effectively identify a variety of negative ions, including O−,O2−,O3−,CO3−,HCO3−,NO3−, etc.[40][41][42]

Application of negative air ions

Health Promotion

The effects of NAI on human/animal health are mainly concentrated on the cardiovascular and respiratory systems and mental health. The impacts of NAI on the cardiovascular system include improving red blood cell deformability and aerobic metabolism and lowering blood pressure[43][44][45]. In terms of mental health, a experiments have shown that after exposure to NAI, performance on all the experimenters test tasks (mirror drawing, rotation tracking, visual reaction time and hearing) was significantly improved[46], and symptoms of seasonal affective disorder (SAD) were alleviated.[47] The effects of NAI in relieving mood disorder symptoms are similar to those of antidepressant non-drug treatment trials, and NAI have also shown effective treatment for chronic depression.[48]

Negative air ions precipitation particulate matter

Environmental Improvement

Negative air ions can be effectively used to remove dust and settle harmful pollutants such as PM. In particular, they can significantly degrade indoor pollutants, improve people's indoor living environment, and purify air quality. Some experts and scholars have used a corona-negative ions generator to conduct experiments on particles sedimentation through three steps: charging, migration, and sedimentation. They found that charged PM will settle faster or sink faster under the action of gravity so that PM will settle/precipitate faster than uncharged PM[49][50][51][52]. In addition, experimental studies have shown that negative air ions have a specific degradation effect on chloroform, toluene, and 1,5-Hexadiene and produce carbon dioxide and water as final products through the reaction.[53]

See also

References

  1. ^ First, Melvin W. (1980). "Effects of Air Ions". Science. 210 (4471): 714–716. Bibcode:1980Sci...210..714F. doi:10.1126/science.210.4471.714. ISSN 0036-8075. PMID 17739525.
  2. ^ Franklin, J L; Harland, P W (1974). "Gaseous Negative Ions". Annual Review of Physical Chemistry. 25 (1): 485–526. Bibcode:1974ARPC...25..485F. doi:10.1146/annurev.pc.25.100174.002413. ISSN 0066-426X.
  3. ^ Goldstein, Naum I.; Goldstein, Roman N.; Merzlyak, Mark N. (1992). "Negative air ions as a source of superoxide". International Journal of Biometeorology. 36 (2): 118–122. Bibcode:1992IJBm...36..118G. doi:10.1007/BF01208923. ISSN 1432-1254.
  4. ^ Fricke, Rudolf G. A.; Schlegel, Kristian (2017). "Julius Elster and Hans Geitel – Dioscuri of physics and pioneer investigators in atmospheric electricity". History of Geo- and Space Sciences. 8 (1): 1–7. Bibcode:2017HGSS....8....1F. doi:10.5194/hgss-8-1-2017. ISSN 2190-5010.
  5. ^ Elster, J.; Geitel, H. (1894). "Photo-Electric Phenomena". Nature. 50 (1297): 451–452. Bibcode:1894Natur..50..451E. doi:10.1038/050451a0. ISSN 0028-0836.
  6. ^ Yates, Alayne; Gray, Frank B.; Misiaszek, John I.; Wolman, Walter (1986). "Air ions: Past problems and future directions". Environment International. Indoor Air Quality. 12 (1): 99–108. Bibcode:1986EnInt..12...99Y. doi:10.1016/0160-4120(86)90019-X. ISSN 0160-4120.
  7. ^ Krueger, Albert Paul; Smith, Richard Furnald (1959). "The Physiological Significance of Positive and Negative Ionization of the Atmosphere". Journal (Royal Society of Health). 79 (5): 642–648. doi:10.1177/146642405907900526. ISSN 0370-7318. PMID 14412202.
  8. ^ Krueger, Albert P.; Smith, Richard F.; with the technical assistance of Eddie Reed (1960). "The Biological Mechanisms of Air Ion Action". The Journal of General Physiology. 44 (2): 269–276. doi:10.1085/jgp.44.2.269. ISSN 1540-7748. PMC 2195092. PMID 13754552.
  9. ^ Krueger, Albert P.; Kotaka, Sadao; Andriese, Paul C.; with the technical assistance of Eddie J. Reed. (1962). "Studies on the Effects of Gaseous Ions on Plant Growth". The Journal of General Physiology. 45 (5): 879–895. doi:10.1085/jgp.45.5.879. ISSN 1540-7748. PMC 2195229. PMID 14459883.
  10. ^ Gilbert, G. O. (1973). "Effect of negative air ions upon emotionality and brain serotonin levels in isolated rats". International Journal of Biometeorology. 17 (3): 267–275. Bibcode:1973IJBm...17..267G. doi:10.1007/BF01804620. ISSN 0020-7128. PMID 4756240.
  11. ^ Hawkins, L. H.; Barker, T. (1978). "Air Ions and Human Performance". Ergonomics. 21 (4): 273–278. doi:10.1080/00140137808931724. ISSN 0014-0139. PMID 668669.
  12. ^ Tom, Gail; Poole, Marilyn Freeman; Galla, Jane; Berrier, Jolie (1981). "The Influence of Negative Air Ions on Human Performance and Mood". Human Factors: The Journal of the Human Factors and Ergonomics Society. 23 (5): 633–636. doi:10.1177/001872088102300513. ISSN 0018-7208. PMID 7319500.
  13. ^ Fornof, K. T.; Gilbert, G. O. (1988). "Stress and physiological, behavioral and performance patterns of children under varied air ion levels". International Journal of Biometeorology. 32 (4): 260–270. Bibcode:1988IJBm...32..260F. doi:10.1007/BF01080025. ISSN 0020-7128. PMID 2466798.
  14. ^ Sirota, T. V.; Safronova, V. G.; Amelina, A. G.; Mal’tseva, V. N.; Avkhacheva, N. V.; Sofin, A. D.; Yanin, V. A.; Mubarakshina, E. K.; Romanova, L. K.; Novoselov, V. I. (2008). "The effect of negative air ions on the respiratory organs and blood". Biophysics. 53 (5): 457–462. doi:10.1134/S0006350908050242. ISSN 0006-3509.
  15. ^ Liu, Yun; Rui, Yueyue; Yu, Bingyan; Fu, Lihu; Lu, Gang; Liu, Jie (2024). "Study on the negative oxygen ion release behavior and mechanism of tourmaline composites". Materials Chemistry and Physics. 313: 128779. doi:10.1016/j.matchemphys.2023.128779. ISSN 0254-0584.
  16. ^ Popov, N. A. (2010). "Evolution of the negative ion composition in the afterglow of a streamer discharge in air". Plasma Physics Reports. 36 (9): 812–818. Bibcode:2010PlPhR..36..812P. doi:10.1134/S1063780X10090084. ISSN 1562-6938.
  17. ^ Ewing, Robert G.; Waltman, Melanie J. (2010). "Production and utilization of CO3− produced by a corona discharge in air for atmospheric pressure chemical ionization". International Journal of Mass Spectrometry. 296 (1): 53–58. Bibcode:2010IJMSp.296...53E. doi:10.1016/j.ijms.2010.08.024. ISSN 1387-3806.
  18. ^ Luts, Aare; Parts, Tiia (2002). "Evolution of negative small air ions at two different temperatures". Journal of Atmospheric and Solar-Terrestrial Physics. 64 (7): 763–774. Bibcode:2002JASTP..64..763L. doi:10.1016/S1364-6826(02)00076-7. ISSN 1364-6826.
  19. ^ de Urquijo, J.; Bekstein, A.; Ducasse, O.; Ruíz-Vargas, G.; Yousfi, M.; Benhenni, M. (2009). "Negative ion clusters in oxygen: collision cross sections and transport coefficients". The European Physical Journal D. 55 (3): 637–643. Bibcode:2009EPJD...55..637D. doi:10.1140/epjd/e2009-00248-8. ISSN 1434-6079.
  20. ^ Ewing, Robert G.; Waltman, Melanie J. (2009). "Mechanisms for negative reactant ion formation in an atmospheric pressure corona discharge". International Journal for Ion Mobility Spectrometry. 12 (2): 65–72. doi:10.1007/s12127-009-0019-8. ISSN 1865-4584.
  21. ^ Fehsenfeld, F. C.; Ferguson, E. E. (1974). "Laboratory studies of negative ion reactions with atmospheric trace constituents". The Journal of Chemical Physics. 61 (8): 3181–3193. Bibcode:1974JChPh..61.3181F. doi:10.1063/1.1682474. ISSN 0021-9606.
  22. ^ Branscomb, Lewis M. (1957), Negative Ions, Advances in Electronics and Electron Physics, vol. 9, Elsevier, pp. 43–94, doi:10.1016/s0065-2539(08)60163-8, ISBN 978-0-12-014509-6, retrieved 2024-09-12
  23. ^ Lin, Hai-Feng; Lin, Jin-Ming (2017). "Generation and Determination of Negative Air Ions". Journal of Analysis and Testing. 1 (1): 6. doi:10.1007/s41664-017-0007-7. ISSN 2509-4696.
  24. ^ Yan, Xiujing; Wang, Haoran; Hou, Zhengyang; Wang, Shunyan; Zhang, Dongyou; Xu, Qing; Tokola, Timo (2015). "Spatial analysis of the ecological effects of negative air ions in urban vegetated areas: A case study in Maiji, China". Urban Forestry & Urban Greening. 14 (3): 636–645. Bibcode:2015UFUG...14..636Y. doi:10.1016/j.ufug.2015.06.010. ISSN 1618-8667.
  25. ^ Luts, Aare; Parts, Tiia-Ene; Laakso, Lauri; Hirsikko, Anne; Grönholm, Tiia; Kulmala, Markku (2009). "Some air electricity phenomena caused by waterfalls: Correlative study of the spectra". Atmospheric Research. 13th International Conference on Atmospheric Electricity. 91 (2): 229–237. doi:10.1016/j.atmosres.2008.02.019. ISSN 0169-8095.
  26. ^ Laakso, L.; Hirsikko, A.; Grönholm, T.; Kulmala, M.; Luts, A.; Parts, T.-E. (2007). "Waterfalls as sources of small charged aerosol particles". Atmospheric Chemistry and Physics. 7 (9): 2271–2275. doi:10.5194/acp-7-2271-2007. ISSN 1680-7316.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  27. ^ Kolarž, P.; Gaisberger, M.; Madl, P.; Hofmann, W.; Ritter, M.; Hartl, A. (2011). "Characterization of ions at Alpine waterfalls". dx.doi.org. Retrieved 2024-09-12.
  28. ^ Zilch, Lloyd W.; Maze, Joshua T.; Smith, John W.; Ewing, George E.; Jarrold, Martin F. (2008). "Charge Separation in the Aerodynamic Breakup of Micrometer-Sized Water Droplets". The Journal of Physical Chemistry A. 112 (51): 13352–13363. doi:10.1021/jp806995h. ISSN 1089-5639.
  29. ^ Lenard, Philipp (1892). "Ueber die Electricität der Wasserfälle". Annalen der Physik. 282 (8): 584–636. doi:10.1002/andp.18922820805. ISSN 0003-3804.
  30. ^ Botti, A.; Bruni, F.; Imberti, S.; Ricci, M. A.; Soper, A. K. (2005). "Solvation shell of OH− ions in water". Journal of Molecular Liquids. Routes from Local Order to Large Scale Cooperativity. 117 (1): 81–84. doi:10.1016/j.molliq.2004.08.013. ISSN 0167-7322.
  31. ^ Luts, Aare; Parts, Tiia-Ene; Laakso, Lauri; Hirsikko, Anne; Grönholm, Tiia; Kulmala, Markku (2009). "Some air electricity phenomena caused by waterfalls: Correlative study of the spectra". Atmospheric Research. 13th International Conference on Atmospheric Electricity. 91 (2): 229–237. doi:10.1016/j.atmosres.2008.02.019. ISSN 0169-8095.
  32. ^ Dwyer, Joseph R.; Uman, Martin A. (2014). "The physics of lightning". Physics Reports. The Physics of Lightning. 534 (4): 147–241. doi:10.1016/j.physrep.2013.09.004. ISSN 0370-1573.
  33. ^ Borra, J-P; Roos, R A; Renard, D; Lazar, H; Goldman, A; Goldman, M (1997). "Electrical and chemical consequences of point discharges in a forest during a mist and a thunderstorm". Journal of Physics D: Applied Physics. 30 (1): 84–93. doi:10.1088/0022-3727/30/1/011. ISSN 0022-3727.
  34. ^ Nishikawa, Kazuo; Nojima, Hideo (2001). "Air Purification Effect of Positively and Negatively Charged Ions Generated by Discharge Plasma at Atmospheric Pressure". Japanese Journal of Applied Physics. 40 (8A): L835. doi:10.1143/JJAP.40.L835. ISSN 0021-4922.
  35. ^ Harrison, R. G.; Carslaw, K. S. (2003). "Ion‐aerosol‐cloud processes in the lower atmosphere". Reviews of Geophysics. 41 (3). doi:10.1029/2002RG000114. ISSN 8755-1209.
  36. ^ Jiang, Shu‐Ye; Ma, Ali; Ramachandran, Srinivasan (2021). "Plant‐based release system of negative air ions and its application on particulate matter removal". Indoor Air. 31 (2): 574–586. doi:10.1111/ina.12729. ISSN 0905-6947.
  37. ^ Jiang, Shu‐Ye; Ma, Ali; Ramachandran, Srinivasan (2021). "Plant‐based release system of negative air ions and its application on particulate matter removal". Indoor Air. 31 (2): 574–586. doi:10.1111/ina.12729. ISSN 0905-6947.
  38. ^ Chang, J.-S.; Lawless, P.A.; Yamamoto, T. (1991). "Corona discharge processes". IEEE Transactions on Plasma Science. 19 (6): 1152–1166. doi:10.1109/27.125038.
  39. ^ Goldman, M.; Goldman, A.; Sigmond, R. S. (1985). "The corona discharge, its properties and specific uses". Pure and Applied Chemistry. 57 (9): 1353–1362. doi:10.1351/pac198557091353. ISSN 1365-3075.
  40. ^ Gardiner, P S; Craggs, J D (1977). "Negative ions in Trichel corona in air". Journal of Physics D: Applied Physics. 10 (7): 1003–1009. Bibcode:1977JPhD...10.1003G. doi:10.1088/0022-3727/10/7/006. ISSN 0022-3727.
  41. ^ Ross, Stuart K.; Bell, Andrew J. (2002). "Reverse flow continuous corona discharge ionisation applied to ion mobility spectrometry". International Journal of Mass Spectrometry. 218 (2): L1–L6. Bibcode:2002IJMSp.218L...1R. doi:10.1016/S1387-3806(02)00693-0.
  42. ^ Hill, C. A.; Thomas, C. L. P. (2003). "A pulsed corona discharge switchable high resolution ion mobility spectrometer-mass spectrometer". The Analyst. 128 (1): 55–60. Bibcode:2003Ana...128...55H. doi:10.1039/b207558j. PMID 12572804.
  43. ^ Iwama, H. (2004). "Negative air ions created by water shearing improve erythrocyte deformability and aerobic metabolism". Indoor Air. 14 (4): 293–297. doi:10.1111/j.1600-0668.2004.00254.x. ISSN 0905-6947.
  44. ^ Iwama, Hiroshi; Ohmizo, Hiroshi; Furuta, Setsuo; Ohmori, Satoshi; Watanabe, Kazuhiro; Kaneko, Toshikazu; Tsutsumi, Kazuo (2002). "Inspired superoxide anions attenuate blood lactate concentrations in postoperative patients:". Critical Care Medicine. 30 (6): 1246–1249. doi:10.1097/00003246-200206000-00014. ISSN 0090-3493.
  45. ^ Ryushi, T.; Kita, Ichirou; Sakurai, Tomonobu; Yasumatsu, Mikinobu; Isokawa, Masanori; Aihara, Yasutugu; Hama, Kotaro (1998). "The effect of exposure to negative air ions on the recovery of physiological responses after moderate endurance exercise". International Journal of Biometeorology. 41 (3): 132–136. doi:10.1007/s004840050066. ISSN 0020-7128.
  46. ^ Hawkins, L. H.; Barker, T. (1978). "Air Ions and Human Performance". Ergonomics. 21 (4): 273–278. doi:10.1080/00140137808931724. ISSN 0014-0139.
  47. ^ Bowers, Bonnie; Flory, Randall; Ametepe, Joseph; Staley, Lauren; Patrick, Anne; Carrington, Heather (2018). "Controlled trial evaluation of exposure duration to negative air ions for the treatment of seasonal affective disorder". Psychiatry Research. 259: 7–14. doi:10.1016/j.psychres.2017.08.040.
  48. ^ Goel, Namni; Terman, Michael; Su Terman, Jiuan; Macchi, Mariana M.; Stewart, Jonathan W. (2005). "Controlled trial of bright light and negative air ions for chronic depression". Psychological Medicine. 35 (7): 945–955. doi:10.1017/S0033291705005027. ISSN 0033-2917.
  49. ^ Uk Lee, Byung; Yermakov, Mikhail; Grinshpun, Sergey A. (2004). "Removal of fine and ultrafine particles from indoor air environments by the unipolar ion emission". Atmospheric Environment. 38 (29): 4815–4823. doi:10.1016/j.atmosenv.2004.06.010. ISSN 1352-2310. PMC 7319258. PMID 32834730.
  50. ^ Mayya, Y. S.; Sapra, B. K.; Khan, Arshad; Sunny, Faby (2004). "Aerosol removal by unipolar ionization in indoor environments". Journal of Aerosol Science. 35 (8): 923–941. doi:10.1016/j.jaerosci.2004.03.001. ISSN 0021-8502.
  51. ^ Grinshpun, S. A.; Mainelis, G.; Trunov, M.; Adhikari, A.; Reponen, T.; Willeke, K. (2005). "Evaluation of ionic air purifiers for reducing aerosol exposure in confined indoor spaces". Indoor Air. 15 (4): 235–245. doi:10.1111/j.1600-0668.2005.00364.x. ISSN 0905-6947.
  52. ^ Berry, David; Mainelis, Gediminas; Fennell, Donna (2007). "Effect of an Ionic Air Cleaner on Indoor/Outdoor Particle Ratios in a Residential Environment". Aerosol Science and Technology. 41 (3): 315–328. doi:10.1080/02786820701199702. ISSN 0278-6826.
  53. ^ Wu, Chih Cheng; Lee, Grace W. M. (2004). "Oxidation of volatile organic compounds by negative air ions". Atmospheric Environment. 38 (37): 6287–6295. doi:10.1016/j.atmosenv.2004.08.035. ISSN 1352-2310.
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