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Living with traffic and industrial pollution

23/9/2018

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In a typical home, inside air leaks out and outside air leaks in - typically resulting in new air from the outside replacing the existing air inside every hour or so​.
This is not a design fault; without a substantial amount of air circulating between the outside and inside, our homes can become “sick” - with condensation and mould damaging the walls and fabric of our houses, aggravating allergies, and complicating respiratory diseases brought on by certain biological agents such as mites and mildew.
Traffic and Industrial 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 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:
  • 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.
Volatile Organic Compounds (VOCs)
​VOCs include a variety of chemicals, some of which can have short- and long-term adverse health effects.
Ozone (O3)
​Ozone can trigger asthma attacks and cause shortness of breath, coughing, wheezing, headaches, nausea, and throat and lung irritation, even in healthy adults.
​Particulates (PM2.5)
​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.
​The challenge is to remove or neutralise these pollutants more quickly than new ones enter the room!
Step 1 - Reduce air leakage

​The first step that we can take to  improve matters is to reduce the quantity of pollution coming inside.
​To do that really well we would have to start from scratch and build homes according to a whole new set of rules, such as the ‘Passivhaus’ standards which employ mechanical ventilation to clean the incoming air in a controlled manner.
​For most of us, that is impractical (and unaffordable!), but we can (if it hasn’t already been done) do a lot to improve the situation by using the well understood techniques for sealing and ventilating that were developed to save energy. 
Typical Sources of Air Leakage
Typical Sources of 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:
  • Budget versions (and sometimes expensive ones!) may have only a thin layer of carbon, which makes them ineffective.
  • The speed of the air through the filter is often too high (so as to achieve a high air flow rating), giving the carbon too little time to be effective.
  • The filter becomes ‘saturated’ and ineffective without the user being able to tell that is the case – and users cannot rely on the manufacturer’s ‘average’ replacement times in areas of high pollution.
  • According to the EPA, gas-phase filters, like activated carbon, cannot readily remove carbon monoxide from the air.
  • Filter replacements, which are typically expensive, need to be frequent to ensure they don’t become saturated.
  • O3 chemically alters the carbon, reducing its efficiency, and requiring even more frequent filter changes.
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.
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​But hydroxyls are only created naturally outside.
​Airora is the only technology that can create that same safe and effective Hydroxyl Cascade inside your home, destroying or neutralising all the key types of gaseous pollutant (CO, NOx, VOCs and O3) and, over time, vaporising key harmful ultra-fine particulates.
​Airora is not a filter. The air to be cleaned does not have to pass through the device; instead, hydroxyls spread throughout the air in a room in seconds by molecular diffusion, reacting with and destroying pollution as they go.
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.

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Hay Fever Basics

3/9/2018

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​​​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.

Symptoms


​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:
  • frequent sneezing
  • runny or blocked nose
  • itchy, red or watery eyes (also known as allergic conjunctivitis)
  • an itchy throat, mouth, nose and ears
​Less commonly, you may experience:
  • the loss of your sense of smell
  • facial pain (caused by blocked sinuses)
  • sweats
  • headaches

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


​Hay fever is not considered a medically serious allergy, unlike peanut allergy or asthma which can cause potentially fatal attacks. The main impact hay fever has on everyday life is upon the general quality of life. Common effects are:
  • regular headaches
  • trouble sleeping
  • loss of productivity at work and in school
  • adverse effects on sporting activities
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​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:
  • ​is the most common allergic disease
  • affects 10-25% of adults in the UK
  • affects 10% of children (aged six-seven) and 15% of those (aged 13-14)
  • is now being seen in children as young as three and four years old

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:
  • tight chest
  • shortness of breath
  • coughing
  • wheezing

Pollen count


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:
  • low: fewer than 30 grains of pollen in every cubic metre of air
  • moderate: 30-49 grains of pollen in every cubic metre of air
  • high: 50-149 grains of pollen in every cubic metre of air
  • very high:150 or more grains of pollen in every cubic metre of air
​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?


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​Most people with hay fever are allergic to grass pollen. However, trees, mould spores and weeds can also cause hay fever. Research suggests that pollution, such as cigarette smoke or car exhaust fumes, can make allergies worse.
There are around 30 types of pollen and 20 types of spore that could cause your hay fever. The pollen that causes hay fever could come from:
  • grass: The majority of people in Ireland with hay fever are allergic to grass pollen,
  • trees: such as birch, oak, ash and cedar, or
  • weeds: such as mugwort and ragweed
​Spores that cause hay fever can come from:
  • fungi, such as wild mushrooms, and
  • mould, for example from compost heaps​

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:
  • From January to April, pollens from trees are the most common cause of hay fever.
  • From May to August, pollens from grass are the most common cause of hay fever. 
  • During the autumn, hay fever may be caused by weeds such as nettles and docks, late flowering plants, and mould and fungal spores.​

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:
  • Perennial rhinitis: In perennial rhinitis, some other allergen, like house dust mite, is involved (symptoms are present all year round but, for some reason, seem worse in the pollen season). To learn more about rhinitis, visit our Rhinitis Information page.
  • Sinusitis: This is inflammation of the sinus cavities, which are empty spaces within the skull, behind the nose. Sinusitis may be caused by allergy, but it may also be caused by benign growths in the nose called polyps. Acute sinusitis can also result from bacterial infection.

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. 
When outside:
  • avoid cutting grass, playing or walking in grassy areas, and camping
  • wear wraparound sunglasses to stop pollen getting in your eyes when you are outdoors
  • change your clothes and take a shower after being outdoors to remove the pollen on your body
  • try to stay indoors when the pollen count is high
  • keep car windows closed - you can buy a pollen filter for the air vents in your car (which will need to be changed every time the car is serviced)
When indoors:​
  • ​keep windows and doors shut in the house - if it gets too warm, draw the curtains to keep out the sun and keep the temperature down
  • do not keep fresh flowers in the house.
  • vacuum regularly, ideally using a machine with a HEPA (high-efficiency particulate air) filter.
  • don't bring pollen indoors – during hay fever season try to change your clothes on arriving home and wash or rinse your hair
  • dry laundry indoors to prevent them collecting pollen from outside
  • damp dust regularly. 
  • Using an air cleaner may help, but it depends on the type of air cleaner (see below)
  • keep pets out of the house during the hay fever season - if your pet does come indoors, wash it regularly to remove any pollen from its fur
  • do not smoke or let other people smoke in your house - ​smoking and breathing in other people's smoke will irritate the lining of your nose, eyes, throat and airways, and can make your symptoms worse.
​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:
  • they can only clean the air that passes through them, and stratification, eddies and more means that some air in the room never passes through the filter
  • they don’t clean surfaces at all and it only takes a small disturbance to put settled pollen back into the air
​The only technology we know of that can over time neutralise pollen throughout the air in a  room and on surfaces is Airora’s ‘Hydroxyl Cascade’ technology.
You can learn more about why traditional air cleaners don’t work well here and why Airora’s unique technology does work here.
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    Author

    Dr Wyatt blogs on his lifetime's experience of Indoor Air Quality Issues.

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