How to choose an air purifier for Multiple Chemical Sensitivity (MCS) and VOC Removal

Over the last twenty years we have helped countless Chemical Sensitivity sufferers choose the correct type of air purifier to alleviate their symptoms and we hope this short guide may in turn help you or someone you know benefit from our experiences.

What causes MCS and what are the most common symptoms?
Chemical Sensitivity can be one of the most difficult medical conditions to live with. It is basically an intolerance to many commonly used, everyday chemicals (VOC's). For some, exposure to simple things like a spray of deodorant or the merest whiff of perfume can set it off, for others it is the chemicals in things like smoke, paint fumes, plastic products, scented products and basic household cleaning products to name but a few. Symptoms vary from person to person depending upon their sensitivity, but the most common ones tend to be tiredness, feeling dizzy, having headaches and even coming out in skin rashes or suffering shortness of breath.

What type of air purifier should be used to combat Chemicals in the air and help relieve these symptoms?
By default, whichever air purifier you ultimately choose will most likely already have a Hepa ( High Efficiency Particulate Arrestor ) filter inside. Almost all air purifiers these days use a Hepa filter to remove airborne pollutants and allergens like traffic pollution, dust mites, pollen, pet dander, viruses and bacteria. However, a Hepa filter on its own is virtually powerless when it comes to removing VOC's from the air. Being fumes, rather than particulates, VOC's fly straight through even the most advanced Hepa unchecked. These harmful chemicals need to be adsorbed after they come through the Hepa filter and before they re-enter the room. The only thing that will effectively adsorb these is a carbon filter. The type and weight of the carbon filter is directly related to just how much of the chemical fumes will be removed. Specialist air purifiers will contain around a kilo or more of genuine carbon. Most cheap and cheerful (and some not so cheap) units found in UK High Street stores contain just a token gesture of carbon. Often this is just a lightweight, thin piece of sponge which has been impregnated with a 'dusting' of carbon. This token amount is all that is required for the manufacturer to claim that their machine removes VOC's, when the reality is however that such a tiny amount is virtually negligible when it comes to actually adsorbing anything at all.

The techy bit! …
In order for a carbon filter to adsorb fumes effectively, the speed at which the air passes through it is crucial. Basically, the longer it takes the contaminated air to travel through the carbon the better. This is called the ‘dwell time’, the longer the air dwells on its way through, the more odour, fumes and gases are adsorbed into it. Therefore the thicker the carbon, the longer the dwell time (good), the thinner the carbon, the shorter the dwell time (bad!).

So, any air purifier with a decent carbon filter inside will remove VOC's and alleviate my MCS symptoms?
Almost, but not quite! The filter is only half the solution, getting all those aggravating VOC's to actually migrate towards the filter to be adsorbed is the other half. If you think about it, no matter how good the filter is, if the fan that sucks the fumes in is too weak to draw them all in quickly (and frequently) enough, then the filter itself is almost irrelevant. So, ideally the correct combination is a genuine carbon filter (not a piece of sponge with carbon impregnated into it) coupled with a fan motor which is powerful enough to actually suck all that chemical infused air into it as fast as possible. Ideally try to choose a machine which is powerful enough to recirculate ALL of the air in the room through the filter around 5 times every hour (more on this below) .

Finally, Room Size - (always read the small print).
This is one of the most common mistakes people make when it comes to choosing an air purifier. We have already explained earlier in this article how it is important to try and choose an air purifier that is powerful enough to drag all of the air in your room size through the filter around five times an hour for it to be genuinely effective. This is often abbreviated to ACPH (Air Changes Per Hour) , however it is easy to be misled on this.

Some manufacturers grossly exaggerate the room sizes that their equipment will operate effectively in. It is common to see air purifiers advertised on the internet and in our High Street stores which claim to be suitable for fairly substantial room sizes. However, the reality is that many of these units could only ever be remotely effective in rooms which are much, much smaller.

One manufacturer who typifies this approach is VAX. Their entry level AP01 air purifier is rated on their own website as being for rooms up to 61m2 - however a quick look at its official airflow ratings prove that in order for it to provide around 5 air changes an hour it would need to be operated in a room no larger than 7.2m2! Their other models like the Pure Air 300 (£299.00) and AP03 (£259.99) are just as misleading in quoting 120m2 and 103m2, when in actual fact their effective application would be in rooms no bigger than 30m2 and 17m2 respectively.

Now compare that to a more specialist air purifier, like the Stadler Form Roger for example. This costs about the same price as the AP03 and yet it is vastly more powerful and contains much more genuine carbon for better VOC removal. There are also some professional machines out there which take Chemical Removal to a whole other level, and which contain heavy duty carbon filters and MerV19 Hepa filters, both of which are not generally found in day to day air purifiers. Officially certified as Class 1 Medical devices Airgle Air Purifiers are widely regarded as being amongst the very best money can buy. However this type of performance comes at a cost, with the AG300 unit costing £750.00.

So the message is, take the advertised room size with a pinch of salt, always ask how many actual air changes the unit will provide in your room – regardless of what is claimed on the box.

Click here to see a list of the best air purifiers for MCS sufferers.

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