How Fresh Air Fights Infections such as Flu and Coronaviris
You might think that going outside in the cold makes you more likely to ‘catch a cold’. But in fact, colds, the flu and COVID-19 spread much more easily inside. Let us explain …
How are infections such as Flu and Coroanvirus spread?
Both flu (and the common cold) and Coronaviruses such as COVID-19 are caused by viruses, which are spread through exposure to respiratory secretions (i.e. an infected person’s sneezes or coughs). The virus can be spread through the air, personal contact (such as a handshake), or by touching contaminated objects.
How long do these viruses remain infectious?
As you can see, these can hang around indoors for up to 72 hours – and people can shed huge numbers of cold / flu viruses into the air which can in turn settle onto surfaces:
Nature’s outdoors remedy - Hydroxyls
However, outside, you’re much less likely to catch these viruses. That’s because Hydroxyl Radicals, which occur naturally and abundantly in the air outside, kill all human pathogens on contact, including cold and flu viruses.
Hydroxyl Radicals are commonly known as ‘Nature’s Detergent’, and we think they are pretty amazing!
Only Airora's technology creates the same remedy indoors, in both the air and on surfaces.
Learn more about hydroxyls >
Airora product development has continually focused on safety. In June 2020, the Airora Professional PAW100/500 product passed an IAQ (Indoor Air Quality) test at the UK's Building Research Establishment (BRE) with flying colours.
The IAQ test measured the amounts of some potentially harmful substances in the ambient air (representing a typical room) before and after using Airora Professional.
Those substances were: CO (Carbon Monoxide), CO2 (Carbon Dioxide), NOx (Nitrogen Oxides), NO2 (Nitrogen Dioxide), Ozone, PM1, PM2.5, PM10 particulates, Formaldehyde, and VOCs (volatile organic compounds).
To pass the test, the air after using the Airora device could not exceed the IAQ guidelines for safe levels for any of these pollutants.
The results demonstrated that Airora products meet IAQ standards across the board.
Moreover, the amounts of every substance measured were far smaller than the maximum safe levels.
We're delighted to be able to confirm that Airora is a people-safe technology.
For detailed results of our IAQ tests, please contact us.
We will soon be conducting efficacy testing of our new Airora products. Please follow us to stay informed.
15 weeks into the COVID-19 pandemic, scientists know a lot more about how the disease is transmitted.
The highest risk for public health is from crowded indoor spaces with poor ventilation, and especially with
prolonged face-to-face interactions. In close proximity, people speaking, coughing, singing, or simply
breathing can produce respiratory droplets containing the COVID-19 (SARS-CoV-2) virus. These droplets
may land on the nose, mouth or eyes of another person close by.
There is also increasing consensus that some droplets may become aerosolized, and hang about in the air. One study due to be published found that SARS-CoV-2 survives aerosolization better than other coronaviruses and maintains infectivity in aerosols for at least 16 h. Strong air conditioners or fans can spread these droplets further within an enclosed space. Last week, a review article published in Science stated that 'a large proportion of the spread of coronavirus disease 2019 (COVID-19) appears to be occurring through airborne transmission of aerosols produced by asymptomatic individuals during breathing and speaking' and that therefore 'For society to resume, measures designed to reduce aerosol transmission must be implemented'.
Droplets may also land on surfaces. Although surface contamination generally has a much lower risk than
airborne particles, studies show that the virus can stay active on plastic and metal for up to 7 days. The
highest risk comes from high-contact furnishings such as door handles, toilet flushes, handrails, payment
terminals, lift/elevator buttons, and, ironically, hand sanitiser dispensers and protective screens. Flushing toilets can also 'create clouds of virus-containing particles', according to recent research published in Physics of Fluids.
Outdoors, where people can usually distance themselves from each other more effectively, the risk is
greatly reduced. Air movement helps to dilute virus-carrying droplets. Critically, hydroxyls are also
abundant in outdoor air, especially in conditions with lots of sunlight and humidity, and these powerful
molecules continually inactivate viruses in the air and on surfaces. However, indoors is where most of us
live, work, do errands like shopping, and spend a lot of our leisure time; realistically, we can’t avoid being
near other human beings, and most of us don’t want to!
Masks, distancing, increased hygiene, and other behavioural changes can all help reduce risks, and of
course medical researchers are working urgently to develop vaccines and effective treatments. However,
other long-term solutions are needed to help us get us back to, and continue to enjoy, our normal way of
life. We’re proud to have developed the world’s first products to provide 24/7 decontamination of entire
indoor spaces - air and surfaces - so people can safely get on with their lives.
Reducing transmission of SARS-CoV-2 - Science, 26 June 2020
How Exactly Do You Catch Covid-19? There Is a Growing Consensus - Wall Street Journal, 16 June
At work, school and seeing friends: How to lower your coronavirus risk - New Scientist, 27 May 2020
The Airora patented technology is a Hydroxyl Cascade air and surface sanitiser capable of destroying all types of harmful bacteria and viruses, including the COVID-19 coronavirus.
While it is not possible at this time (for safety reasons) to test our technology directly against the COVID-19 virus, we know that Airora's technology destroys ALL types of pathogenic viruses, including those in the coronavirus family (which includes the SARS-CoV-2 coronavirus that causes COVID-19), in the air and on surfaces.
This is demonstrated by the testing carried out by Public Health England's microbiologists at Porton Down using MS2 Coliphage virus as a surrogate. In every test, our process quickly rendered MS2 Coliphage inactive in the air and on surfaces.
The microbiologists at Porton Down use MS2 Coliphage as a gold-standard surrogate for pathogens because it is exceedingly difficult to inactivate. If you can use a process to inactivate MS2 Coliphage then that process would be expected to inactivate all types of pathogenic virus and bacteria. Like all coronaviruses, MS2 is a positive sense single-stranded RNA virus and studies have shown that it is 7 to 10 times more resistant to denaturation (i.e. harder to inactivate) than a coronavirus. In the Porton Down tests, our technology was demonstrated to kill 99.9999% of MS2 Coliphage in an 18-cubic-metre testing chamber in less than 5 minutes.
Airora creates a 'Hydroxyl Cascade' which is well known to destroy all human pathogens, both viruses and bacteria. Our technology has been demonstrated in multiple leading independent testing facilities to quickly, efficiently and safely destroy human pathogens, both viruses and bacteria, in the air and on surfaces.
Hydroxyl Radicals, often called 'nature's detergent', are lethal to both pathogenic viruses and bacteria (gram –ve & +ve), for example MRSA, C. difficile, Salmonella, Norovirus, cold and flu viruses, and coronaviruses. NASA even deployed hydroxyl air purification against Anthrax.
As well as destroying airborne pathogens, hydroxyl radicals strip them, layer by layer, from smooth exposed surfaces.
Hydroxyls kill bacteria, viruses and mould spores by reacting with the lipids and proteins in their thin, delicate cell wall causing lysis (breaking down of cell membranes). Pathogenic viruses suffer from oxidation of their surface structures; when hydroxyls react with viruses, they disrupt the lipid envelope and/or capsid (protein shell) around the virus and inactivate the protein used to enter human cells. Hydroxyl radicals also penetrate the interior of the virus and disrupt the genome (RNA content). These reactions inactivate the virus, rendering it completely harmless and unable to infect humans and animals.
Other safety and efficacy tests of Airora technology have been successfully performed in labs as well as real world settings (a coffee shop, care home, and cinema), by institutions such as the UK Building Research Establishment (BRE), the University of Ottowa, and the FDA Laboratory in Rochester, NY.
View detailed testing data: Testing and Verification of Airora’s Patented Technology.
Learn more about how Airora destroys different types of pollution, including viruses: The Chemistry of Hydroxyl Radical Air Cleaning.
Read an example of hydroxyls inactivating human coronaviruses.
Image source: https://en.wikipedia.org/wiki/2019%E2%80%9320_coronavirus_pandemic#/media/File:SARS-CoV-2_49534865371.jpg
For The World Health Organisation (WHO) has declared the COVID-19 coronavirus outbreak a pandemic. The WHO continues to be a trusted source of the latest information about this unprecedented situation, with frequent updates posted at who.int/emergencies/diseases/novel-coronavirus-2019 as well as via Twitter @WHO.
Key advice from the WHO on minimising the spread of infection by SARS-CoV-2 includes:
The WHO also provides useful information about wearing a mask.
The UN has also just launched a new global multilingual portal for information on COVID-19: un.org/coronavirus
Health guidance on the COVID-19 pandemic is changing daily and varies by region, so please consult your local and national health authority for the most accurate information relevant to your circumstances.
Airora & Viruses
Airora's patented air purifying technology produces a cascade of Hydroxyl Radicals, often called 'nature's detergent'. Hydroxyls have been shown to kill all airborne bacteria and viruses that are known to harm people, including Colds, Influenza, MRSA, C-difficile, Norovirus, and Coronaviruses. As well as destroying airborne pathogens, hydroxyl radicals strip them, layer by layer, from smooth exposed surfaces.
Airora's technology was tested for efficacy against pathogens by the UK Government’s Health Protection Agency at Porton Down, where it was demonstrated to kill 99.9999% of MS-2 Coliphage (a test surrogate for pathogenic respiratory viruses) in an 18m3 testing chamber in less than 5 minutes.
Other safety and efficacy tests have been successfully performed in labs as well as real world settings (a coffee shop, care home, and cinema), by institutions such as the UK Building Research Establishment (BRE), the University of Ottowa, and the FDA Laboratory in Rochester, NY. For detailed results, see our webpage on the Testing and Verification of Airora’s Patented Technology.
The team behind Airora will soon be launching a personal wearable air purifier device, which can be worn during your commute, travel, or in public spaces. To receive the latest updates about this product, please register your email and follow us on Facebook, Twitter or Instagram @AiroraPurifier.
The Environmental Protection Agency (EPA) estimates that our indoor air is nearly 5x more polluted than outdoor air. Some homes may even have 100x more pollution.
Here are thirteen common sources of indoor air pollution:
1. Chlorine bleach
2. Household cleaning chemicals, paints and solvents
3. Synthetic fragrances, perfumes and deodorizers
4. Dry cleaned clothes
5. Tobacco smoke
6. Biological pollutants
7. Pet dander
8. Carpets and upholstery
9. Building and decorating materials
11. Office and craft materials
12. Combustion pollutants
13. External pollution
Can Air Purifiers Help?
This then is the conundrum; we need air to circulate from outside to inside, but in areas with substantial external pollution that circulation continuously brings harmful outside pollution into our homes.
Outside vs Inside
Outside, Nature wages a powerful war of attrition against atmospheric pollution.
Wind disperses pollution, diluting its local effects. Natural chemical and photochemical interactions create an abundance of ‘hydroxyl radicals’ (called ‘Nature’s Detergent’ by scientists) which attack and neutralise a wide range of pollutants, and rain and snow wash pollution and its by-products out of the air.
Of course, in the urban environment, pollution can build up where it is created more quickly than nature can remove it.
Inside, the natural conditions which create hydroxyls are absent, and pollution, well, it hangs around for us to breathe it in!
What does the pollution consist of?
Before deciding on an effective strategy for reducing pollution leaking in from outside, it is necessary we understand the scope and nature of the pollution we are attempting to neutralise.
Historically, the main air pollution problem in both developed and rapidly industrialising countries has typically been high levels of smoke and sulphur dioxide emitted following the combustion of sulphur-containing fossil fuels such as coal, used for domestic and industrial purposes.
These days, the major threat to clean air is now posed by traffic emissions. Petrol and diesel powered vehicles emit a wide variety of harmful pollutants, principally carbon monoxide (CO), oxides of nitrogen (NOx), volatile organic compounds (VOCs) and particulate matter (PM2.5). Additionally, the photochemical reactions resulting from the action of sunlight on nitrogen dioxide (NO2) and VOCs create ozone.
Carbon Monoxide (CO)
CO (carbon monoxide) is a dangerous, colourless gas which reduces your blood’s ability to carry oxygen and can make you ill.
Oxides of Nitrogen (NOx)
The Committee on the Medical Effects of Air Pollution recently reviewed the evidence for the adverse health effects of NOx and concluded that:
Volatile Organic Compounds (VOCs)
VOCs include a variety of chemicals, some of which can have short- and long-term adverse health effects.
Ozone can trigger asthma attacks and cause shortness of breath, coughing, wheezing, headaches, nausea, and throat and lung irritation, even in healthy adults.
Particulate matter, also called PM or soot, consists of microscopically small solid particles or liquid droplets suspended in the air.
PM2.5 refers to what are termed “fine particles” of below 2.5 microns in diameter. The smaller the particles, the deeper they can penetrate the respiratory system and the more hazardous they are to breathe.
Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 microns in diameter). UFPs are the main constituent of airborne particulate matter. Owing to their numerous quantity and ability to penetrate deep within the lung, UFPs are a major concern for respiratory exposure and health
PM pollution can cause lung irritation, aggravates the severity of chronic lung diseases, causes inflammation of lung tissue, causes changes in blood chemistry and can increase susceptibility to viral and bacterial pathogens.
Step 1 - Reduce air leakage
Click here for a good basic guide on what can be done to both save energy (and money!) and reduce air leakage.
Simply reducing leakage won’t solve the pollution problem (reducing leakage by, say, 50%, won’t really help in pollution terms; the air inside will still be as polluted as the air outside), but the lower the leakage rate, the more effective the use of air cleaning technology will be.
Think about it this way: Sit an air cleaner, however effective, next to an open window, and it will be overwhelmed by new pollution to the point where it will have no effect. For an air cleaner to be effective, you have firstly to slow the flow of new air into a room to give it time to work.
So, reducing leakage is only the first step in mitigating the pollution problem. The second step is using an air cleaner that really works!
Step 2 – Remove or neutralise internal pollution
Having reduced air leakage, let’s look at our options for removing or neutralising polluting gasses and particulates before we breathe them in:
Can filters reliably remove or neutralise all of CO, NOx, VOCs and O3?
X No! CO, NOx, VOCs and O3 are gasses that cannot be filtered out by HEPA, Ionising (Ionic) or Electrostatic (Electronic) filters, which are all designed to filter out particulates, not gasses.
What about activated carbon filters?
These are sometimes suggested to remove these gasses from the air and can be implemented either as stand-alone filters or in combination with a HEPA filter to capture the larger particulates.
There are many problems with using this type of filter to address outside air pollution:
X So, all in all, activated carbon filters are not effective as a solution for removing gaseous pollutants.
OK, how about HEPA filters?
The ‘gold standard’ for particulate filters is the High Efficiency Particulate Air (HEPA) filter. Filters meeting the HEPA standard remove 99.97% of particles that have a size 0.3 microns or larger from the air passing through them.
However, 90% of particulates in the air, including the most harmful ones, are smaller than that, so most HEPA air purifiers only catch a fraction of all particulates, and none of the potentially most harmful ones.
X Hepa Filters will only remove 10% of the particulates.
So, filters simply aren't effective at removing industrial and traffic pollution?
Correct. And air filters don't work well in the real world anyway! Not only are there no suitable and affordable filters for the purposes we require, the unfortunate fact is that portable air filtration devices, of whatever type, are not very effective at treating any kind of pollution.
All portable air filters share the same fundamental shortcoming; even if they do filter the air passing through them effectively, they only clean that limited amount of air that passes directly through them, not all of the air in the room. You can find out more here.
Then along came Airora…
Let us return to where we started, outdoors.
Outside, Nature wages a powerful and successful war of attrition against atmospheric pollution by employing natural chemical and photochemical interactions to create an abundance of ‘hydroxyl radicals’ (known as ‘Nature’s Detergent’ by scientists) which attack and neutralise a wide range of pollutants.
Find out more about how Airora breaks down harmful gasses and vaporises key ultra-fine particulates that are too small to be trapped by HEPA filters here.
Hay fever is a type of allergic rhinitis caused by pollen or spores. Allergic rhinitis is a condition where an allergen (something that causes an allergic reaction) makes the inside of your nose inflamed (swollen).
Hay fever usually occurs in spring and summer, when there is more pollen in the air. Trees, grass and plants release pollen as part of their reproductive process. Mould and fungi also release tiny reproductive particles, called spores.
People with hay fever can experience their symptoms at different times of the year, depending on which pollens or spores they are allergic to.
Hay fever symptoms vary in severity and your symptoms may be worse some years than others, depending on the weather conditions and the pollen count (see below). Your symptoms may start at different times of the year depending on which types of pollen you are allergic to.
The symptoms of hay fever include:
Less commonly, you may experience:
Hay fever is an allergic reaction
Hay fever symptoms are caused by protein molecules in pollen grains. The immune system ‘over-reacts’ to these allergens, which it manifests in the form of an allergic reaction. Immune molecules known as Immunoglobulin E are produced and these cause the release of the inflammatory chemical called histamine from mast cells (a type of immune cell).
It is histamine that produces the characteristic symptoms of an allergic reaction.
A non-allergic person’s immune system will not produce this reaction on exposure to allergens in pollen.
Hay fever and everyday life
Research shows that students’ academic performance may be affected during exams, given that the exam season usually coincides with the height of the pollen season.
How common is hay fever?
Hay fever is a relatively new disease, first described in 1819. It took nine years to accumulate enough hay fever cases to present a paper on this new condition to a medical journal. Now hay fever is much more common, particularly in the UK, which has more cases than anywhere else in the world (followed closely by Ireland, New Zealand, Australia and Canada). Hay fever:
Hay fever and asthma
If you have asthma, your asthma symptoms may get worse when you have hay fever. Sometimes, asthma symptoms only occur when you have hay fever. These symptoms include:
Hay fever symptoms are likely to be worse if the pollen count is high. The pollen count is the number of grains of pollen in one cubic metre of air.
Air samples are collected in traps set on buildings two or three storeys high. Taking samples from this height gives a better indication of the pollen in the air from both local and distant sources. Traps on the ground would only collect pollen from nearby trees and plants.
The air is sucked into the trap and the grains of pollen are collected on either sticky tape or microscope slides (glass plates). The pollen is then counted. Samples are usually taken every two hours, and the results are averaged for a 24-hour period.
The pollen forecast is usually given as:
Hay fever symptoms usually begin when the pollen count is over 50. The pollen count is usually given as part of the weather forecast during the spring and summer months.
Which pollens are you allergic to?
Spores that cause hay fever can come from:
When is there most pollen?
Different trees and plants produce their pollen at different times of the year.
Depending on which pollen you are allergic to, you may experience your hay fever symptoms at different times. In the UK:
The effect of the weather
The amount of sunshine, rain or wind affects how much pollen plants release and how much the pollen is spread around. On humid and windy days, pollen spreads easily. On rainy days, pollen may be cleared from the air, causing pollen levels to fall
During their pollen season, plants release pollen early in the morning. As the day gets warmer and more flowers open, pollen levels rise. On sunny days, the pollen count is highest in the early evening.
Confusing hay fever with other conditions
A person who appears to be suffering hay fever symptoms may be suffering from:
Alleviating hay fever
It is very difficult to completely avoid pollen or spores. However, reducing your exposure to the substances that trigger your hay fever should ease the severity of your symptoms. Follow the advice below to avoid being exposed to excessive amounts of pollen and spores.
Finally, check the pollen count regularly to know when your efforts need to be more concentrated.
Can an air cleaner help?
While numerous manufacturers of ‘air cleaners’ / ‘air filters’ claim to be able to clear pollen from the air, they can only reduce, not eliminate, the problem, because:
Pets produce dander (microscopic skin flakes that they shed), and the protein in it can cause severe allergic reactions for some people.
Pet dander is a little like dandruff flakes, only smaller; at around 2-3 microns in size it easily becomes airborne and can be inhaled.
Dander can cause allergic reactions for a long period and may persist for many months after the pet has left the house.
The origin of the allergens is in the pet’s urine, sweat and saliva. These excretions adhere to their skin, for example when they clean themselves, and become of the dander they shed.
Cat dander is the most commonly inhaled allergen after house dust mite and pollen. Other types of pet, such as dogs, mice and guinea pigs, may similarly cause allergic reactions.
Because they are so light, pet allergens are widely distributed in the air, remaining airborne for several hours before settling, only to be easily stirred up into the air again.
Clearly, the best way of avoiding pet dander is to not have a pet! However, many of us love our pets too much to do without them! In that case, there are various measures you can take to reduce your exposure, including controlling the pet’s access to certain rooms, and using an effective air purifier to neutralise the dander.
Pet allergies and your health
Pet allergies are known to play a role in:
People with a tendency to allergy (known as atopy), should avoid owning pets if possible. Unfortunately, some people who don’t initially exhibit allergic reactions, can nevertheless develop symptoms after continued exposure.
Why pet dander causes an allergic reaction
Allergens usually enter the respiratory system through the nose. Mast cells in the airways release mediators, which trigger the allergy attack. This attack is an overreaction of the body’s immune system to the invading allergens that have bonded with antibodies. Mast cells are one of the human body’s principal defences against allergens and are found in connective tissue and mucous membranes. One of its biological functions is innate immunity including involvement in host defence mechanisms against parasitic infestations, tissue repair, etc.
Pet dander is very ‘sticky’ and can stay in your hair, clothes and other belongings for long periods of time. This is why you can still suffer symptoms when you are away from the pet causing those symptoms.
The major cat related allergens are found in the cat’s sweat and saliva and the major dog related allergen is found in its saliva.
What animals cause allergy problems?
A wide range of animals can cause allergic reactions including cats, dogs, birds, mice, rats, guinea pigs, rabbits, parrots and hamsters.
Male cats shed more allergen than females, and cats shed more allergen than dogs. Horses produce very powerful allergens and old mattresses stuffed with horsehair can produce symptoms. Snakes, lizards and other reptiles, and even insects, may shed dander-like skin particles into the air.
Perhaps the best pets for a pet allergy sufferer are fish, as they are not associated with allergy!
What about hypoallergenic dogs?
Avoiding pet allergens
Before turning to technological or other solutions, careful allergen avoidance / environmental allergen control is important. For example:
And don't forget - Are you sure pet allergen is really the cause of your allergy? It could be that house dust mite, mould or pollen is the real culprit. An allergy specialist will be able to offer an allergy test to pinpoint the true allergen.
Can an air cleaner help?
While numerous manufacturers of ‘air cleaners’ / ‘air filters’ claim to be able to clear pet dander from the air, they can only reduce, not eliminate, the problem, because:
There is a long history of disease caused by inhaled particles that stretches from observations by Agricola and Paracelsus in the 15th and 16th centuries up to the present. In the 20th Century the twin scourges of asbestos and crystalline silica (quartz) exerted a terrible toll of death and disease. The bad old days when these dust related lung diseases were common are fortunately gone but as we move into the 21st century a new particle type, the ultra-fine particle, has emerged as one with a potential role in causing disease.
What are ultra-fine particles and where do they come from?
Ultrafine particles (UFPs) are particulate matter of nanoscale size (less than 0.1 μm or 100 nm in diameter). This size class of ambient air pollution particles, which are far smaller than the regulated PM10 and PM2.5 particle classes, are believed to have several more aggressive health implications than those arising from larger particulates.
There are two main divisions that categorise types of UFPs. UFPs can either be carbon-based or metallic, and metallics can be further subdivided by their magnetic properties.
UFPs are the main constituent (by number) of airborne particulate matter. UFPs arise from a range of indoor sources that including printers and copiers, cooking, tobacco smoke, vaping, candles, chimney cracks and vacuum cleaners. Those indoor sources are often considerably supplemented by the penetration of contaminated air from outside, where vehicles and industry are the major contributors.
Unlike their larger PM10 and PM2.5 brethren, UFPs that are inhaled, because they are very small, can penetrate tissue and / or be absorbed directly into the bloodstream where effects may become apparent quickly.
Exposure to UFPs, even if the underlying materials are not very toxic, may cause oxidative stress, inflammatory mediator release, and could induce heart disease, lung disease, and other systemic effects. A robust association has been observed between fine particulate levels and both lung cancer and cardiopulmonary disease.
The exact mechanism through which UFP exposure leads to health effects remains to be fully understood, but effects on blood pressure may play a role. It has recently been reported that UFP is associated with an increase in blood pressure in schoolchildren with the smallest particles inducing the largest effect.
Reducing exposure to UFPs indoors
Standard HEPA filters as fitted to almost all air cleaners only collect particles down to around PM2.5 although specialist HEPA filters such as 'HyperHEPA clean room grade filters' can collect particles across much of the ultra-fine spectrum.
Ion generators have been found to have mediocre UFP removal performance and ultraviolet germicidal irradiation (UVGI) has demonstrated very limited or no UFP removal capabilities.
In addition, all filter-based devices, whatever the underlying technology, share the same shortcoming which limits their effectiveness. They only clean the air that passes through the device, not all the air in the room.
Then along came Airora ...
The advent of the Airora air purifier offers a new approach which promises to reduce the number of ultra-fine particles throughout a room.
In this approach, the ultra-fines are subject to in-situ oxidation by hydroxyl radicals. Oxidation by hydroxyls is known to fragment organic carbon ultra-fine particles, which typically constitute most ultra-fines indoors, changing them over time from solids to harmless gasses.
Research on this important subject continues!
Dr Wyatt blogs on his lifetime's experience of Indoor Air Quality Issues.