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.
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!
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.
We often spend up to 90% of our time indoors (at home, work or at school), so exposure to indoor air pollution is potentially much more damaging to our health. That is why the World Health Organisation considers indoor air pollution as one of the main health threats today, and states that around 3% of the global burden of disease is directly attributable to it.
Indoor air pollution
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.
In our homes the build up of both bacteria and viruses in the air is much greater than outside.
Sources of pollution
Damp dusting, not just dry dusting, is needed to reliably remove dust rather than just spreading it around. Most carpets are a major reservoir for dust and for every six rooms in a house around 40 pounds of dust is generated in a single year, much of which is human skin as we regularly shed our outer layer of skin as part of a continuous renewal process.
The main components of dust which can affect your health indoors are:
Prevention of indoor air pollution
It is always better to try to prevent indoor air pollution occurring before attempting to reduce or remove it:
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.
Then along came Airora ...
There is now however a new generation of air purifiers of which the Airora 4-in-1 is the first (and currently only) one. These air purifiers use the naturally occurring ‘hydroxyl radical cascade’ process found in the outside atmosphere to clean internal air (and exposed surfaces) of the full range of pollutants; allergens and irritants, pollutant gasses, bacteria and viruses and smells.
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.
Sprays, plug-ins and gels
Chemical sprays, plug-ins and gels for home perfuming are hugely popular but they can include an array of hazardous substances which may cause lung damage and tumours, interfere with our hormones and aggravate conditions such as asthma.
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.
The evidence of harm is mounting:
But manufacturers refute such concerns
Manufacturers of air fresheners, however, maintain that their products are safe. In June 2015, SC Johnson, which makes Glade air fresheners, published specific information on most of the ingredients in its products for the first time.
Company chairman Fisk Johnson says: 'We take great care in making ingredient choices to offer products that are both safe and effective.'
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, SC Johnson maintains that all its fragrance ingredients, even those not listed, are safe: 'While they are not disclosed, the remaining ingredients also must meet our strict standards.'
Incense are no better
Millions of us burn them every day to send spiritually inspiring wafts of spiciness around our homes. Research shows that ingredients such as frankincense can cause chemical changes in our brains, lifting our moods.
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.
Burning incense releases tiny chemical particles which can become trapped in our lungs, causing potentially dangerous inflammatory reactions.
The research also found that incense particles from commonly used ingredients agarwood and sandalwood are more toxic to our cells' DNA than tobacco smoke.
Nor are scented candles
Scented candles bring another dimension, adding that subtle hint of aromatic bliss. Scientists remain unmoved however, voicing extreme concerns about the pollution that they are bringing to our lives.
In March 2015, a team of experts tested six scented candles, with such aromas as clean cotton, strawberry and kiwi fruit.
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.
The candles also gave off significant levels of VOCs. Furthermore, the study warned that you don't even need to light such candles because simple evaporation will enable them to pollute your home.
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.
Then along came Airora 4-in-1 ...
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:
A study on Household Cleaning Sprays and Asthma by Professor Zock of the Municipal Institute of Medical Research in Spain, was published in the American Journal of Respiratory and Critical Care Medicine in 2007.
Professor Zock undertook the research as ‘Cleaning work and professional use of certain cleaning products have been associated with asthma, but respiratory effects of nonprofessional home cleaning have rarely been studied’.
According to the study, the exposure to certain cleaning products during professional cleaning work has been associated with MCS and other asthma symptoms for some time. This study, however, focused on the respiratory effects of non-professional home cleaning.
The study identified 3,503 persons, in 10 countries, doing the cleaning in their homes and who were free of asthma at baseline. Frequency of use of 15 types of cleaning products was obtained in a face-to-face interview. The researchers studied the incidence of asthma defined as physician diagnosis and as symptoms or medication usage at follow-up. Associations between asthma and the use of cleaning products were statistically analysed.
Participants were assessed for asthma, wheeze, physician diagnosed asthma and allergies during follow-up. They were also asked to report the number of times per week they used cleaning products.
Two thirds of the study population who reported doing most of the cleaning were women. 6% of them had asthma at the time of follow-up. Fewer than 10% of them were full-time homemakers.
Risks were predominantly found for the commonly used glass-cleaning, furniture, and air-refreshing sprays. Cleaning products not applied in spray form were not associated with asthma.
The report's conclusions
American Journal of Respiratory and Critical Care Medicine Vol. 176. pp. 735-741, (2007); The Use of Household Cleaning Sprays and Adult Asthma, An International Longitudinal Study.
Dr Wyatt blogs on his lifetime's experience of Indoor Air Quality Issues.