Effective anti-bacteria and anti-viral air treatment device

Abstract

The invention provides an air treatment device (100) configured to deactivate one or more of bacteria and viruses from air, the device (100) comprising a deactivating material (121) comprising for at least 80 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond, the air treatment device (100) further comprising a gas flow generation device (130), wherein the air treatment device (100) is configured to provide said deactivating material (121) into a space with an emission rate (S) of at maximum 250 mg/h from a release area (1112).

Claims

1. An air treatment device configured to deactivate one or more of bacteria and viruses from air, the device comprising a deactivating material comprising for at least 80 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond, the air treatment device comprising: a gas flow generation device configured to control the emission of said deactivating material into a space, wherein the deactivating material is entrained by a gas flow generated by the gas flow generation device within the air treatment device, a device chamber with an inlet opening and an outlet opening, the air treatment device in operation configured to comprise the deactivating material at least partially enclosed by the device chamber, a deactivating material unit situated within the device chamber, configured to host the deactivating material, the deactivating material unit comprising an opening in direct fluid contact with the device chamber, wherein the air treatment device is configured to provide said deactivating material into said space with an emission rate (S) of at maximum 250 mg/h from a release area.

2. The air treatment device according to claim 1, wherein the gas flow generation device is configured to introduce air from the space via the inlet opening into the device chamber and to transport at least part of the deactivating material with the air via the outlet opening into the space, wherein the air treatment device is configured to provide said deactivating material into the space with an emission rate (S) of at maximum 250 mg/h from said outlet opening.

3. The air treatment device according to claim 1, wherein the deactivating material comprises for at least 95 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond, wherein the deactivating material has a boiling point selected from the range of 150-300 C. or has a boiling point range at least partly overlapping with said range of 150-300 C., and wherein the deactivating material comprises one or more of eucalyptol (1,8-cineol) and thymol.

4. The air treatment device according to claim 1, complying with one or more of the following conditions (i) having a controllable emission rate (S) and (ii) wherein the air treatment device is limited at an emission rate (S) selected from the range of 0.5-50 mg/h from said release area.

5. The air treatment device according to claim 1, comprising a plurality of release areas, wherein the air treatment device is configured to provide said deactivating material into the space with said emission rate (S) from each of said release areas.

6. The air treatment device according to claim 1, wherein the deactivating material unit is configured as refillable unit, and wherein the deactivating material is comprised by a deactivating material cartridge.

7. The air treatment device according to claim 1, wherein the gas flow generation device comprises an ionic wind generator.

8. The air treatment device according to claim 1, wherein the deactivating material comprises for at least 90 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond.

9. The air treatment device according to claim 1, wherein the deactivating material comprises for at least 98 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond.

10. An air treatment system comprising: (i) an air treatment device configured to deactivate one or more of bacteria and viruses from air, the device comprising a deactivating material comprising for at least 80 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond, the air treatment device further comprising: a gas flow generation device configured to control the emission of said deactivating material into a space, wherein the deactivating material is entrained by a gas flow generated by the gas flow generation device within the air treatment device, a device chamber with an inlet opening and an outlet opening, the air treatment device in operation configured to comprise the deactivating material at least partially enclosed by the device chamber, a deactivating material unit situated within the device chamber, configured to host the deactivating material, the deactivating material unit comprising an opening in direct fluid contact with the device chamber, wherein the air treatment device is configured to provide said deactivating material into said space with an emission rate (S) of at maximum 250 mg/h from a release area, and (ii) a control unit configured to control the emission rate (S).

11. The air treatment system according to claim 10, configured to maintain a concentration of the deactivating material in air in the space at a level selected from the range of 0.001-1 mg/m.sup.3.

12. The air treatment system according to claim 10, further comprising a sensor configured to sense one or more of (i) a concentration of a component in air of the deactivating material in a space, (ii) an ultra fine particles concentration in air in a space, (iii) a conversion product concentration in a space, and (iv) another physical or chemical parameter in said space, and wherein the control unit is configured to control the emission rate (S) as function of a sensor signal of said sensor and a corresponding predetermined value for one or more of said component, said ultra fine particles, said conversion product, and said physical or chemical parameter.

13. A kit of parts comprising: (i) an air treatment device configured to deactivate one or more of bacteria and viruses from air, the air treatment device comprising a deactivating material comprising for at least 80 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond, the air treatment device further comprising: a gas flow generation device configured to control the emission of said deactivating material into a space, wherein the deactivating material is entrained by a gas flow generated by the gas flow generation device within the air treatment device, a device chamber with an inlet opening and an outlet opening, the air treatment device in operation configured to comprise the deactivating material at least partially enclosed by the device chamber, a deactivating material unit situated within the device chamber configured to host the deactivating material, the deactivating material unit comprising an opening in direct fluid contact with the device chamber, wherein the deactivating material unit is configured as a refillable unit configured to host one or more of said cartridges, and wherein the air treatment device is configured to provide said deactivating material into said space with an emission rate (S) of at maximum 250 mg/h from a release area, and (ii) a plurality of cartridges comprising said deactivating material.

14. The kit of parts according to claim 13, further comprising a control unit configured to control the emission rate (S).

15. A cartridge comprising a deactivating material for use in an air treatment device, the device configured to deactivate one or more of bacteria and viruses from air, the deactivating material comprising at least 80 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond, the air treatment device comprising: a gas flow generation device configured to control the emission of said deactivating material into a space, wherein the deactivating material is entrained by a gas flow generated by the gas flow generation device within the air treatment device, a device chamber with an inlet opening and an outlet opening, the air treatment device in operation configured to comprise the deactivating material at least partially enclosed by the device chamber, a deactivating material unit situated within the device chamber configured to host the deactivating material, the deactivating material unit comprising an opening in direct fluid contact with the device chamber, the deactivating material being at least partially enclosed by the device chamber, wherein the air treatment device is configured to provide said deactivating material into said space with an emission rate (S) of at maximum 250 mg/h from a release area.

16. The cartridge according to claim 15, wherein the deactivating material comprises for at least 95 wt. % of one or more of said terpenes and terpenoids.

17. The cartridge according to claim 15, wherein the deactivating material comprises for at least 80 wt. % of one or more of Menthol, Isomenthol, Neomenthol, Neoisomenthol, Menthone, Isomenthone, Eucalyptol (1,8-cineol), 1,4-cineol, m-Cymene, p-Cymene, Carvacrol, Thymol, p-Cymen-8-ol, Cuminaldehyde, Cuminylalcohol, Iridoid, and Seco-iridoid.

18. A method for deactivating one or more of bacteria and viruses from air in a closed air space, the method comprising: providing an air treatment device into said closed air space, wherein said air treatment device includes a device chamber with an inlet opening and an outlet opening, and a deactivating material unit situated within the device chamber configured to host the deactivating material, the deactivating material unit comprising an opening in direct fluid contact with the device chamber, arranging a deactivating material into a deactivating material enclosure partially enclosed by the device chamber of the air treatment device, and activating a gas flow generation unit of the air treatment device to control the emission of said deactivating material into said closed air space with an emission rate of at maximum 250 mg/h from a release area, wherein said activation comprises introducing external air into the device via said inlet opening and transporting at least part of the deactivating material with the air via the outlet opening, wherein said deactivating material comprises at least 80 wt. % of one or more of a terpene and a terpenoid having no aliphatic unsaturated bond, with a concentration of the deactivating material in air in said space at a level selected from the range of 0.001-1 mg/m.sup.3.

19. The method, according to claim 18, wherein the deactivating material comprises one or more of Menthol, Isomenthol, Neomenthol, Neoisomenthol, Menthone, Isomenthone, Eucalyptol (1,8-cineol), 1,4-cineol, m-Cymene, p-Cymene, Carvacrol, Thymol, p-Cymen-8-ol, Cuminaldehyde, Cuminylalcohol, Iridoid, and Seco-iridoid.

20. The method according to claim 18, further comprising additionally controlling the emission of said deactivating material into said closed air space via a heater unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

(2) FIGS. 1a-1j schematically depict some aspects of the invention.

(3) The schematic drawings are not necessarily on scale.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) FIG. 1a schematically depicts an air treatment device 100 configured to deactivate biological species, such as especially one or more of bacteria and viruses from air. The atmosphere or space from which these may be deactivated is indicated with reference 5. The device 100 comprises a deactivating material 121 comprising for at least 80 wt. % of one or more of a terpene and a terpenoid (both further also indicated as terpene or terpenes) having no aliphatic unsaturated bond. The air treatment device 100 further comprises a gas flow generation device 130. The air treatment device 100 is especially configured to provide said deactivating material 121 into a space with an emission rate S of at maximum 250 mg/h from a release area 1112. Reference F indicates the gas flow generated by the gas flow generation device 130; reference F indicates the gas flow comprising said deactivating material 121.

(5) FIGS. 1b-1e schematically depicts some other variants. Here, the device 100 comprises in most variants a device chamber 102 with an inlet opening 111 and an outlet opening 112. The air treatment device 100 is in operation configured to comprise the deactivating material 121 at least partially enclosed by the device chamber 102, wherein the gas flow generation device 130 is configured to introduce air from the space via the inlet opening 111 into the device chamber 102 and to transport at least part of the deactivating material 121 with the air via the outlet opening 112 into the space. Further, the air treatment device 100 is configured to provide said deactivating material 121 into the space with an emission rate S of at maximum 250 mg/h from said outlet opening 112. Reference 120 indicates a deactivating material cartridge. Reference 140 indicates a deactivating material unit (herein also indicated as active material enclosure), wherein the deactivating material 121 may be arranged, such a in the form of a cartridge 120 comprising said deactivating material 121. The deactivating material unit 140 may comprise an opening 143. This opening 143 may be in direct fluid contact with the device chamber 102, as shown in FIGS. 1b and 1c, or may be arranged external from the chamber 102, such as schematically depicted in FIGS. 1d and 1e. FIGS. 1a-1e, but also FIGS. 1f-1i do not show e.g. a heater. Emission of the deactivating material may amongst others be controlled by the gas flow generation device 130 and/or by a heater (or heating unit). For control of the emission solely via the gas flow generation device 130, especially the embodiments of FIGS. 1b and 1c may be suitable. However, other embodiments than depicted may also be applied. The deactivating material 121 may especially be entrained by the gas flow F/F, especially either already within the air treatment device (see FIGS. 1b and 1c (and 1e)) and/or in the gas flow generated in the space (see FIGS. 1d and 1e). In FIG. 1d (and also 1e) the deactivating material 121 can be considered to be associated (at least partly) with an external part of the air treatment device 100. FIGS. 1f-1g schematically depict variants with a plurality of release areas 1112, such as a plurality of openings 112, with the latter variant extensions, such as tubes, e.g. to serve different spaces, such as different rooms. However, the release areas 1112 may also be arranged in the same space, such as a large room, or a hall, etc.

(6) FIG. 1h schematically depicts an air treatment system 1000 comprising i) the air treatment device 100 (without further details) according to any one of the preceding claims and ii) a control unit 1010 configured to control the emission rate S. further, such system 1000 may include one or more sensors 1020, e.g. configured to sense one or more of i) a concentration of a component in air of the deactivating material 121 in a space, ii) an ultra fine particles concentration in air in a space, iii) a conversion product concentration in a space, and iv) another physical or chemical parameter in said space, and wherein the control unit 1010 is configured to control the emission rate S as function of a sensor signal of said sensor 1020 and a corresponding predetermined value for one or more of said component, said ultra fine particles, said conversion product, and said physical or chemical parameter. FIG. 1i schematically depicts such device 100 or system 1000 for application for a space 5. FIG. 1j is elucidated below. One or more of the sensor 1020 and the control unit 1010 may be integrated in the air treatment device 100 but may also be configured external of the air treatment device 100.

(7) It appears that terpene materials that are used may create UFP's and formaldehyde because of reactions with ambient ozone. This is not desired. Hence, the present invention especially focus on those terpenese that surprisingly show a substantially lower formation of one or more of such species. Very few reports focus on terpenes/terpenoids that do not react with ozone and therefore do not form such potentially hazardous products.

(8) During the last 15 years, extensive work took place to quantify exposure risks from Volatile Organic Components (VOC's) in ambient air. Both Chinese and WHO issued guidelines for formaldehyde levels while Germany issued guidelines for monocyclic and bicyclic terpenes/terpenoids.

(9) It appears that with the present device and deactivating material such guidelines can be met, while nevertheless have the above indicated advantages in relation to deactivating bacteria and virusses. In a specific embodiment, the device described herein is configured to emit non-reactive monocyclic terpenes.

(10) The risks of UFP's or the concern about the health consequences of exposures to high UFP levelsare known in the art. Although UFP guidelines are not yet issued, UFP levels are commonly classified using typical UFP levels in nature, metropolitan and industrial environments. UFP levels are considered acceptable when remaining at levels that occur in clean natural/indoor environments:

(11) TABLE-US-00001 Type UFP levels [1/cm.sup.3] Clean air in the alps <1.000 Clean office air 2.000-4.000 Outside Air in urban area 10.000-20.000 Polluted outside air (smog) >50.000 Cigarette smoke >50.000 Workplaces (like welding) 100.000-1.000.000

(12) Until the appearance of guideline values that are applicable to UFP's generated by terpenes/terpenoids, UFP levels of 4.000/cm.sup.3 and lower are considered to be acceptable. Hence, especially the device and system are configured and/or can be controlled to keep UFP levels below 10.000/cm.sup.3, more especially, even more especially below 4.000/cm.sup.3. To this end, a sensor may be used to sence the level of UFP in the relevant space, such as a room in a house or an office space. Especially, UFP is defined as (air-borne) particulate matter of nanoscale size, especially less than 100 nanometres in diameter (or equivalent diameter in the case of a non-spherical particle, i.e. the diameter which would be obtained when the particle with the same volume would be a spherical particle).

(13) However, in the course of the present invention it was found that terpene emitting devices can de-activate effectively bacteria and viruses while still fulfilling the air quality guidelines for terpenes, formaldehyde while maintaining UFP values to levels encountered in clean air or even very clean air.

(14) Hence, especially the invention provides a device that is able to emit controlled low levels of a terpenes/terpenoids at levels such as terpene/terpenoid 1 mg/m.sup.3, like 0.6 mg/m.sup.3, especially like 0.2 mg/m.sup.3. Especially, a terpene is used that does not react with ozone. Further, especially the device is configured and the terpene is selected to de-activate bacteria and/or viruses with each independently more than 10% according to the tests which were executed. Especially, a device may be provided thatwhile especially fulfilling one or more of the conditions as defined above may optionally generate (or induce generation of) UFP and/or formaldehyde at levels occurring in clean natural/indoor air or far below the indoor air quality guidelines. For instance, the UFP level may especially remain below values characteristic for clean air (<4000/cm.sup.3), more especially below about 1000/cm.sup.3. Further, especially the formaldehyde level may remain below a values of about 100 g/m.sup.3, and especially below a level of 30 g/m.sup.3, especially below a level of 10 g/m.sup.3.

(15) Test were carried out with a basic device 100 which contains a fan as gas flow generation device 130, housing inlet or inlet opening 111 and housing outlet or outlet opening 112, as described in FIG. 1b. The device used in our tests contained an enclosure or deactivating material unit 140, that, in the experiments, included 2 mL of a liquid that consists one or more terpene and/or terpenoid compounds.

(16) In alternative measurements, tests were performed with the basic device that contains a cartridge with two small holes and filled with paper that was impregnated with 2 mL of a mixture of 75 wt % eucalyptol and 25 wt % thymol (Eucalyptol: Sigma Aldrich 99% purity, product code C80601; Thymol: Sigma Aldrich >99.5% purity, product code T0501).

Experiment 1

(17) The device was operated in a 1 m.sup.3 box with an air exchange rate of 1.5 hr.sup.1 that was ventilated with purified air with and without the addition of approx. 60 ppb which equals 120 g/m.sup.3 ozone. The following items were analyzed at the outlet of the chamber: total VOC content, concentration levels of individual VOC's, levels of formaldehyde and other aldehydes, ozone levels, and UFP levels.

(18) In the absence of ozone, eucalyptol and thymol contents at the outlet were approx. 670 and 6 g/m.sup.3 as measured with Tenax/GC-MS techniques which, considering the air exchange rate of the test chamber, corresponds to hourly evaporation rates of 1000 and 10 g/hr, respectively. The lower thymol levels agrees with the lower volatility of thymol (as demonstrated by higher boiling points: Eucalyptol: 176-177 C. thymol: 232 C.). It appeared that at least about 96 wt. % of the emitted VOC's (especially defined as C1-C16) consist of eucalyptol and thymol and less than about 4 wt. % of the emitted volatile compounds consistes of very volatile VOC's (<C6). The emitted VOC's contain less than 1% of reactive terpenes (-pinene and -pinene). Hence, less than 20 wt. %, especially less than about 1 wt. % of the deactivating material, that is proliferated in air, comprises terpenes with aliphatic double bonds. In the presence of 120 g/m.sup.3 ozone, formaldehyde is formed at 3-4 g/m.sup.3 which is far below some current guideline values, even below average outdoor concentrations. Simultaneously, in the presence of ozone, UFP levels increase with values below 1000 l/cm.sup.3 which are also measured in very clean air. The observed small increase of formaldehyde and UFP is tentatively attributed to the low level of reactive terpenes in the eucalyptol/thymol mixture.

(19) From the data studied, it appeared that the creation of undesired side-products can be controlled at very low levels if high purity non-reactive terpenes/terpenoids are used. Note that low levels of side-products were detected even while high eucalyptol/thymol levels were created. In fact, even at such high eucalyptol/thymol levels, the created levels of undesired side-products are below the minimum detection limits of most analytical devices and the formaldehyde/UFP increase will not be noted in household environments because of the typically much higher background levels and the large variations of these background values as caused by human activities and outdoor air quality variations.

Experiment 2

(20) Further, the impact of using low-purity i.s.o. high-purity terpene/terpenoid materials. In this test, the cartridge was loaded with 2 mL of 75/25 wt %/wt % mixture of eucalyptol and thymol. The same thymol was used as above. However, in this case a low-purity eucalyptol sample of natural origin was used. It was found that many types of terpenes/terpenoids were emitted besides eucalyptol. Eucalyptol accounted for less than 25% of the total emitted terpenes/terpenoids. The remaining 75% contains reactive terpenes such as limonene, -terpinene, terpinolene, -pinene that may react with ozone to a.o. UFP's. The total level of emitted VOC levels was approx. 3 times higher than in the above experiment. Further, in the presence of 120 g/m.sup.3 ozone, UFP levels increase to above 150.000/cm.sup.3 which is 2-3 orders of magnitude higher than found in the above first experiment.

(21) Detailed analysis showed that, in the presence of ozone, levels decrease of reactive terpenes like -terpinene, terpinolene and limonene and levels increase of acetone, formic acid, acetic acid. Formaldehyde is formed at 20 g/m.sup.3, approx. 5 times higher than in the first experiment. Hence, surprisingly the use of low-purity terpene/terpenoid materials like essential oils can result in the formation of UFP's and side products to levels that exceed guideline values or values typically occurring in pure outdoor air.

Experiment 3

(22) The effectiveness of the terpenes to de-activate air-borne bacteria and viruses was also determined.

(23) The two experiments were performed using two different bacterial species: (1) Staphylococcus epidermidis (ATCC12228) is a gram-positive bacterium that is part of the normal human flora, typically the skin flora, and less commonly the mucosal flora. Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are at risk of developing infection and these infections are generally hospital-acquired. S. epidermidis is a particular concern for people with catheters or other surgical implants because it is known to cause biofilms that grow on these devices; (2) MS-2 Bacteriophage is an icosahedral, positive-sense single-stranded RNA virus that infects the bacterium Escherichia coli. It is commonly used as a surrogate test microorganism for viruses.

(24) Culture preparation: The Staphylococcus epidermidis used in the tests was prepared by inoculating 100 ml of sterile Tryptone Soya Broth (Oxoid, UK) with a 0.1 ml aliquot of previously frozen cells (in 40% glycerol). The broth was then incubated at 37 C. for 24 hours and shaken at 100 rpm. After 24 hours incubation the culture is assumed to be at the boundary between the exponential and stationary growth phases. After incubation the culture was centrifuged and re-suspended in sterile ringers solution and 1 ml of this suspension was used in the nebulizer as described below.

(25) The MS-2 bacteriophage was prepared by inoculating 100 ml of tryptone soya broth with an aliquot of a pure culture of E. coli. The culture was incubated until the culture until reached the exponential growth phase this has been estimated to take around 8 hours at 37 C. Incubating at a lower temperature overnight may achieve the same growth phase. The absorbance of the culture was measured at 600 nm in order to determine if log growth has been achievedan OD600 of between 0.5-1.0 has been suggested as indicative of log phase growth. Once the culture was in log phase growth it was inoculated with the MS2 phage culture and put back into the shaking incubator until cell lysis occurredthis has be suggested to be as little as 30 minutes or as long as 18 hours. Once cell lysis occurred the culture was centrifuged at 10,000-15,000 g for 15 minutes and the supernatant containing the phage was removed. This supernatant containing the MS-2 phage was used in the nebulizer as described in the following section.

(26) Experimental methodology: the experiments were carried out in the aerobiological test chamber, which consists of a 32.25 m.sup.3 hermetically sealed negatively pressurised chamber in which the air flow rate, temperature and relative humidity can be constantly controlled and monitored. The experiments were carried out with the ventilation system set at 1.5 AC/hr (air cycles per hour) at ambient temperature (approx 20 C.) and relative humidity (approx 50%). This means that 1.5*volume of test chamber is supplied every hour. During the microbiological experiments the bacterial aerosols were generated using a 6-jet Collison nebuliser operating at a flow rate of 12 l/min and at a pressure of 20 psi. This was connected to the room via a 25 mm diameter pipe which terminated in a plastic sphere containing twenty four 3 mm diameter holes through which the aerosol was dispersed. Air samples were collected through a plastic pipe located immediately in front of the extract grille. This pipe was connected to a six stage Andersen sampler loaded with sterile agar plates. During the sampling process air passed through the sampler and the bacteria were deposited onto the agar plates. The sampling time was varied depending upon the concentration of the bacterial culture with the aim of collecting between 200 and 300 colony forming units on the agar plates. During the experimental period the temperature, relative humidity and negative/positive ion concentrations were also monitored for 20 minute periods during the control periods and 30 minutes during the device testing periods. Readings were taken every 0.5 seconds and the data used to determine the mean value over a 1 minute period and this is plotted on the graphs in the results section.

(27) The test procedure: In this set of experiments two different types of test procedure were used depending upon the device that was being tested. The first procedure was a first standard testing procedure and the second was an extended test developed in house. The main difference in the test procedure was the amount of time allowed for the device to operate before the test samples were taken. In the standard first test procedure this is 30 minutes and in the extended inhouse test procedure this was 2 hours. When a terpene device had been used the chamber was vented at maximum ventilation rate for 2 hours between tests to ensure that no residual terpene remained in the air inside the chamber.

(28) The test room was set up as shown in FIG. 1j prior to the start of each experimental run and the chamber door closed and locked and both the sampling port (c) and the nebuliser port (d) sealed. Reference a indicates an air inlet; reference b indicates an air outlet; reference c indicates a sampling port or sampling point; reference d indicates the point at which the bacterial/fungal aerosol is introduced, i.e. the nebuliser port; and reference e indicates the location of the device (as described herein).

(29) Air fans were then switched on and operated at maximum speed (approx 12 AC/hr) for 30 minutes in order to ensure the chamber was sterile. The air fans create the air-flow of 1.5 AC/hr. These fans (located outside the test chamber, similar to all equipment that control temperature (T) and relative humidity (% RH) in the test chamber) are not shown in FIG. 1j. During this purging period the test device remained switched off. During the initial purging period the pre-sterilised nebuliser was prepared and filled with 100 ml of bacterial/phage suspension at a concentration of approximately 10.sup.5 organisms/ml of sterile distilled water. The nebuliser was then connected to the inlet tube ready for the start of the experiment. In both test procedures after the initial purging period the ventilation rate was reduced to 1.5 AC/hr and nebulisation of the bacterial culture then began and the concentration in the test chamber was allowed to stabilize again. A total of ten samples were then taken at approximately 3 minute intervals during which time the device remained switched off and these are the control samples. During the whole experimental period the temperature and relative humidity was measured.

(30) The agar plates were incubated at 37 C. for 24 hours after which the number of colonies on each plate were counted. All the counts were then subjected to positive hole correction in order to account for multiple impaction. The corrected counts for each set of plates (stages 5 and 6) were added together to give a total count and multiplied to give a count per m.sup.3 of test chamber air. Each set of samples represents ten replicates taken during steady state, the first five being the concentration without the device and the second with the device. The mean was taken of the ten replicate samples to give a mean concentration with and without the device. This allowed the mean reduction in concentration to be calculated used to give an indication as to the efficacy of the device.

(31) In order to determine the statistical significance of the results a t-test was carried out on the data sets (Control and Test Period). The purpose of the test is to determine whether the means of the two data sets are statistically different from each other. The test yields a p-value and the smaller the p-value the less likely the difference between the two data sets is the result of chance.

(32) Two replicate experiments were carried out using the basic device without the deactivating material (another material with terpenes was used, not complying with the herein defined conditions) as defined herein, a reference measurement, and with deactivating material as defined herein against aerosols of MS2 bacteriophage. A cfu/m.sup.3 reduction in the range of 20.2-25.9% was found.

(33) Also the effect of the basic apparatus, again with a reference measurement and with the deactivation material as defined herein, on aerosols of S. epidermidis was measured. The data showed that the concentration in cfu/m.sup.3 was reduced with of 22.4%.

(34) In a further evaluation it appeared that deactivating material not according to the invention may include relatively large amounts of d-limonene, -pinene and camphene, of which the first two react with ozone to generate small amounts of UFP's and formaldehyde (further information can be provided on request).

Experiment 4

(35) In this experiment, also data from the other experiments described herein are included. Three deactivating materials were tested: (1) eucalyptol (99%)+thymol (99.5%) in a weight ration 3:1, (2) a material comprising 40% limonene including other terpenes, including ozone reactive species; and (3) an eucalyptol (25%) and other terpenes, including ozone reactive species. The following results were obtained in a number of experiments, with e.g. different amounts of starting materials (hence, ranges are given):

(36) TABLE-US-00002 Terpene/ Formal- S. terpenoid UFP dehyde epidermidis MS-2 level level level deactivation deactivation (mg/m.sup.3) (/cm.sup.3) (g/m.sup.3) (%) (%) eucalyptol 0.12-0.72 <1000 <2 14-43 12-29 (99%) + thymol (99.5%) in a weight ration 3:1 40% 0.1-0.3 50,000 6 22 23 limonene including other terpenes, including ozone reactive species eucalyptol 2.6 150,000 20 n.m. n.m. (25%) and other terpenes, including ozone reactive species

(37) It appears that the deactivating material as defined herein provides the best balance in results. It further appears that high purity non-reactive terpenes de-activate bacteria and viruses effectively while fulfilling air quality standards and creating low if any additional amounts of nano-particles. In the table, n.m. indicates not measured; these were not measured as it was clear that the amount of side products, especially double bond containing terpenes (and the possible concomitant undesired reaction products) would be much too high).

Experiment 5

(38) Below some conditions are given for different deactivation materials/deactivating material components, for different rooms. It is assumed that the device will operate in the following conditions:

(39) Room volume: V m.sup.3

(40) Ventilation rate: Q dimensionless, (Q is the total hourly air volume that enters the room via ventilations, expressed as a fraction of the room volume)

(41) This means, in a 100 m.sup.3 room with ventilation factor=0.25, every hour 25 m.sup.3 air enters the room via ventilation.

(42) In normal closed household rooms, ventilation factors below 0.25 are rarely observed.

(43) With windows open, the ventilation rate can increased to above 10, meaning that 1000+m.sup.3 of air enter the room every hour by ventilation

(44) Terpene emission strength S: mg/h

(45) The terpene levels increase to steady state concentration C.sub.ss that is characterized by:
S=Q*V*C.sub.ss
or
C.sub.ss=S/(Q*V)

(46) TABLE-US-00003 Css V Q S Type (mg/m.sup.3) (m.sup.3) (dimensionless) (mg/h) Monocyclic terpene 1 25 0.5 12.5 Monocyclic terpene 1 50 0.5 25 Monocyclic terpene 1 100 0.5 50 Monocyclic terpene 1 200 0.5 100 Bicyclic terpene 0.2 25 0.5 2.5 Bicyclic terpene 0.2 50 0.5 5 Bicyclic terpene 0.2 100 0.5 10 Bicyclic terpene 0.2 200 0.5 20

(47) Assume the device does not specify a minimum room size, e.g. cartridges that emit more than 25 mg/h may create too high terpene levels in rooms of consumer homes. Most especially, terpene emission rates should remain below 25 mg/h, even more especially below 12.5 mg/h in order to generate also acceptable terpene levels in closed rooms of 50 and even 25 m.sup.3, respectively. If hourly evaporation rate of the device exceeds 250 mg/h, measures may have to be taken in most of the rooms or other spaces.

(48) In an embodiment, the device may specify a minimum room size in which it should be operated (at this moment not observed at the market). In this case, the cartridge emission rate may e.g. be below 0.5*V.sub.min with V.sub.min equaling the recommended minimum room size of the device.

(49) It is especially desired that 20 wt. % or less of the emitted deactivation material consists of terpenes/terpenoids with reactive aliphatic double bonds. Further, it is especially desired that total of mono-terpene and terpenoid levels in the absence of ozone are in total below 1 mg/m.sup.3, especially below 0.2 mg/m.sup.3 for bicyclic terpenes. Further, especially the UFP levels in the outlet of the 1 m.sup.3 box remain below 10.000/cm.sup.3, more especially below 4000/cm.sup.3, yet even more especially below 1000/cm.sup.3 when operating in the presence of 100 g/m.sup.3 ozone. Further, especially the formaldehyde levels in the outlet of the 1 m.sup.3 box remain below 10 g/m.sup.3 when operating in the presence of 100 gr/m.sup.3 ozone.

Experiment 6

(50) Some further measurements were done with setups as describe above. Data in relation to particle generation and ozone consumption as function of type of terpene were determined.

(51) The table below shows nanoparticle levels formed in a 26.5 m.sup.3 test chamber, with terpene concentrations of approx. 1 mg/m.sup.3 and with an initial ozone concentration of 100 ppb ozone. It is clear that carvacrol, eucalyptol, etc., show best performance.

(52) The table also shows the reduction of ozone levels as a result of generating a terpene concentration of 1 mg/m.sup.3 within the 26.5 m.sup.3 test chamber. It is clear that e.g. eucalyptol and thymol is most desired amongst these four options.

(53) The following data were obtained:

(54) TABLE-US-00004 average O.sub.3 Particle yield O.sub.3 max. Terpene consumption in 10.sup.6/mol Error in % 36 wt % menthol + 64 2% 391.2 76% wt. % menthone Thymol 2% 498.2 70% Eucalyptol 2% 779.9 66% Carvacrol 0% 851.8 14% Eugenol 15% 18742.9 19% Geraniol 54% 57608.1 13% (not depicted) Linalool 44% 76911.2 11% Limonene 31% 94003.4 15% y-terpinene 19% 112499.9 14%