​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:

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, 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!

​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. 

​CO (carbon monoxide) is a dangerous, colourless gas which reduces your blood’s ability to carry oxygen and can make you ill. 

The Committee on the Medical Effects of Air Pollution recently reviewed the evidence for the adverse health effects of NOx and concluded that:

• Short-term exposure to NO2 likely causes respiratory ill health, may cause an increase in hospital admissions for heart problems, and may cause an increase in overall mortality.
• Long-term exposure to NO2 may cause an increase in respiratory and cardiovascular mortality, children's respiratory symptoms, and decreased lung function.

​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.

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.

​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!

​Having reduced air leakage, let’s look at our options for removing or neutralising polluting gasses and particulates before we breathe them in:

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.

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.

​​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.

​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.

​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. 

​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.

​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 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.

​In the open air, 'Hydroxyl Radical Cascades' are continuously created by the complex chemical interactions that occur naturally in the atmosphere. Hydroxyls are the powerful but entirely safe and natural air cleaning agent, often referred to by scientists as 'Natures Detergent', which continuously decontaminate the air and gives 'fresh air' that clean and refreshing feel that we all love.

​Indoors, the natural atmospheric ingredients that continuously create hydroxyl radicals don't exist and allergens remaining active, smells remain smelly and bacteria and viruses constantly build up in the air and on surfaces. Consequently, indoor air is generally much more polluted than outdoor air, yet until recently it has received far less public attention. 

​Indoor air pollution is a complex mixture of microbes and substances in the air that are potentially harmful to health. The composition of this indoor air pollution can vary greatly depending, for example, where you live and on the contents of your home.

​In a home in a non-urban setting for example, house dust mite, pollen and mould spores can be a major cause of indoor air pollution and related health problems. In a new-build home or office, fumes from paints and insulation, new carpet and furniture can significantly contribute to the pollution. Especially in industrial or built up areas, traffic and industry pollution also play an increasing part in indoor air pollution.

The main components of dust which can affect your health indoors are:

• house dust mite
• mould spores
• pollen
• soot
• pet dander (including cat saliva)
• particulate cigarette smoke
• bacteria and viruses

From 0.1 microns and smaller, pollution falls into the nanoparticle and molecular size range and includes:

• the gaseous, that is non-particulate, components of cigarette smoke
• combustion products such as carbon monoxide and nitrogen oxides from boilers and cookers
• volatile organic compounds (VOCs) such as formaldehyde, which slowly seeps out from carpet or medium-density fibreboard often used in DIY or flat pack furniture and ​as found in a wide range of household products including cleaning solutions, air fresheners, aerosol toiletries and paint​
• ozone, which at too high a level is a known lung irritant
• radon is a radioactive gas that can be found in homes in certain areas if they are built on rocks containing uranium which naturally decays to radon

It is always better to try to prevent indoor air pollution occurring before attempting to reduce or remove it:

• if you smoke, it is best to do so outside and to ask smoking visitors to do likewise
• If you suspect you live in a radon-affected area, get the radon level in your home tested and take appropriate corrective advice and action
• check any DIY products or household aerosols or air fresheners for VOC content

Read the label and note whether the product should not be used in an enclosed space and remember that there are often more 'environmentally-friendly' alternatives to conventional paints, glues and similar products, so choose wisely:

• avoid MDF and other products which release formaldehyde into an enclosed environment
• getting rid of clutter, which attracts dust, will help reduce mould spores, bacteria and house dust mite
• carpet is a prime reservoir for house dust mite - consider replacing your carpets with hard flooring
• invest in a leakage free HEPA vacuum cleaner
• keep humidity low to discourage mould and house dust mite

Where the main source of pollution is internal rather than external then letting fresh air into your home to displace internally polluted air is a good way of improving indoor air quality.

​Where the main source of pollution is internal rather than external, it is helpful to open windows after bathing, showering or cooking so that damp and mould don't build up.

An effective air purifier can play an essential part in reducing indoor air pollution in your home or place of work. But the key word here is ‘effective’ and the unfortunate truth is that most traditional air purifiers are not very effective!

​Various types of traditional air purifier focus on different pollutants, typically pollens, spores and other particles or on gaseous pollutants. Some combine technologies to address more than one type of pollutant.

​But all have the same drawback, they only clean the air passing through the device and rely, to only limited effect, on a high throughput of air to draw in pollution from the ever changing air in the room. However good the filter mechanism, they will only ever clean a modest proportion of pollutants from the air in a room because constant air changes, re-contamination, re-circulation and eddy formation means that there are always significant airborne pollutants in a room which have not been drawn into the device.

​However, evidence has been increasing for some time that all of these products contain industrial chemicals which can, among other things, damage lungs, aggravate asthma and cause tumours.

​Many air fresheners employ carcinogens, volatile organic compounds (which are characterised by their low boiling point which mean they form a gas at room temperature) which are known to increase the risk of asthma in children and known toxins such as phthalate esters in their formulas.

​However, not all of the ingredients used in the actual perfumes are fully listed and could well be made up of many different chemicals.

​However, incense's mystic allure has been clouded by new findings warning that its fumes may be more dangerous than cigarette smoke, causing cancerous mutations in our DNA.

​Behind their labels, however, lay a host of potentially dangerous industrial chemicals, including formaldehyde at levels which, with long-term exposure, are known to raise the risk of respiratory problems and cancer.

​Most scented candles are made with paraffin, which brings other problems. The oil by-product gives off ultra-fine soot particles containing acetone, benzene and toluene, usually seen in diesel emissions, and known carcinogens.

​Why try to 'cover up' smells such as wet dog, cigarette smoke, damp, toilets and cooking? Airora 4-in-1 simply removes such smells and creates a wonderfully fresh, clear and clean atmosphere. Don't just take our word for it, our independent test panel says Airora makes them feel: ​