/ Health, Home & Energy

Is your home making you sick?

indoor pollution cleaning spray

Talk about air pollution, and it’s likely you’ll think of car emissions and polluted streets. But we spend 90% of our lives indoors, and the odourless and unseen gases, chemicals and small particles in the air, could literally make you sick.

Worse still, the products you’re using to mask the bad stuff – the lemon and pine you associate with cleaning products – could actually be the bad stuff.

Some people are more susceptible to the effects of indoor pollutants too – for example, if you suffer from asthma, are sensitive to allergens indoors or have heart and lung disease.

Looking for air purifiers? We’ve tested 10 models to see how well they remove pollen, dust and smoke from the atmosphere. 

Indoor pollution put to the test

So, where’s the evidence of indoor pollution? We sent lab technicians to three ordinary semis: a supposedly ‘draughty’ Victorian one; a 1950s house made airtight with improvements such as double glazing and cavity wall insulation; and a new-build.

We wanted to see how much pollution was generated before and after bursts of common activities in kitchens, bathrooms, living-rooms and bedrooms. For example, when we vacuumed, did the cleaning, used air-fresheners and scented candles, cooked a fry-up and burned the toast.

We discovered surprisingly high levels of pollutants with potential long-term health effects in all the test houses.

For example, we found very high levels of volatile organic compounds (or VOCs) in every room we tested. Results were as much as 34 times the UK Building Regulations recommended maximum level – although measured over a busy 30 minutes, not 24 hours.

This was after activities including burning candles and using plug-in air fresheners, scented washing powder and toiletries such as antiperspirant and perfume.

What are VOCs?

VOCs are chemicals found in a wide variety of materials in the home and from outdoors, that can evaporate into the air at room temperature, producing vapours that we inhale.

VOCs (especially terpenes including limonene and pinene) can combine with ozone from outside air, particularly during hot weather, to form gases including formaldehyde. This is a breathing irritant that can cause sensitisation reactions, and – at very high levels – is carcinogenic.

We also saw very high increases in particulate matter – tiny particles that can enter your lungs, potentially causing serious health problems over time – in all our test-house kitchens.

How you can breathe easy

So what does this mean for you? Well, this shouldn’t make you anxious about every scented candle you burn, or open fire you light. This is about the longer-term view.

In workplaces, employers are required to provide ventilation for adequate fresh air. Inside our own homes however, the quality of the air is in our own hands, and it’s all about controlling sources of pollution and maximising ventilation.

Choose products and activities that will minimise pollution in the first place, ventilate before and after polluting activities such as cooking, vacuuming and using toiletries. Keep trickle vents open, use extractor fans and don’t block air bricks.

Are you concerned about indoor air pollution? What do you do to keep your home ventilated?


I find that products that have a vanilla scent give me an instant headache and make me feel really nauseous. I’ve given away quite a few scented candles because of the reaction I have when/if I burn them.

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My advice is to avoid buying household products sold as sprays or aerosols.

I am an asthmatic and some scented products can leave me short of breath. When staying away from home my first job is to round up reed diffusers, plug-in air fresheners and even bowls of fresh potpourri. I consign them to the back of a cupboard, out of harms way.

At home, I keep the trickle vents above my windows open and the house has a chimney, which helps provide ventilation. I usually use the cooker extractor hood when cooking and always when frying.

Thanks for this Conversation, Joanna. Is there any more information about the VOCs discovered in the Which? tests done on properties?

Early double glazing installations rarely had trickle vents and they are still regarded as an optional feature rather than the default provision. I think they are essential to maintain a cross-flow of air in a home even in cold weather. They don’t all have to be open but it is good to have at least one open on each floor on each side of the house that has a window. Keeping internal doors open helps cross-ventilation. Modern enclosed bathrooms and en suite shower rooms don’t help because the extractor fans never pull out enough air to remove the particles quickly and freshen the atmosphere, and bathrooms are probably the worst rooms for using pollutants for a variety of purposes.

Only in the last decade or so have double-glazed casement windows had two-position locking latches so that a small ventilation gap can be left open. Not a good idea to leave them in that position on the ground floor when the house is vacant or overnight because the window can be prised open, but on upper floors they can be left like that while residents are in bed; they are also good in children’s rooms because the window is effectively locked ajar and cannot be opened any wider.

Even in the winter when the central heating is on all day it is a good idea to open a window or a garden door from time to time just to change the air and make the house smell fresh; it doesn’t have to be for long.

I am not sure that we should live in a totally sterile environment, and all food preparation and cooking releases some ‘pollution’, but as a society I think we have become too heavily influenced by hygiene marketing and have an array of sprays, gels, carpet powders, plug-ins and other things that just add to the toxic overload and all competing with each other to achieve an unnatural fragrance that a good blast of fresh air will supply for nothing [unless you live near a soap factory or a die works or in Bury St Edmunds which has a massive beet-sugar factory in the middle of the town that covers the entire district with a sickly atmosphere – not harmful though, I understand, just too much of a good thing].

Hairspray is another product that can have an adverse affect on some people and historically it has already had two potentially carcinogenic propellant aerosols removed from it (vinyl chloride and methylene chloride) in the last ten years. Specific ingredients are now referred to as fragrances and are not listed on the label so it is not known what has replaced them.

I have now switched the highly perfumed laundry powder I used to use to Waitrose own unperfumed brand for sensitive skins. It certainly does a good job on my cotton white laundry and I am very impressed with the result. I have yet to find a washing up liquid that doesn’t make me sneeze.

My upstairs double glazed casement windows don’t have trickle vents but instead have the two positioned locking latches (John mentions in his comment above,) which are usually kept open in the main bedroom when I am at home. There is more than enough ventilation in my kitchen, which is always tested during the annual boiler service and I also use the extractor fan when cooking. I always open the bathroom window
even in very cold weather after showering and close the door to keep the rest of the house warm.

While effective ventilation is good for healthy living it is even better to stop using products that cause the problems in the first place. The combination of unknown chemicals and hermetically-sealed living arrangements is probably responsible for more health problems than we realise. And it’s not just in our homes – shops, hotels, restaurants, pubs, cinemas, and all sorts of other places are using cleaning sprays, carpet deodorisers, laundry and dry-cleaning chemicals, floor polishes, and other products which get embedded in the fabric and furnishings, suspended in the atmosphere, and recirculated round the air-conditioning system.

I was interested that, in the Which? test, one of the properties used was a Victorian semi. The Victorian builders were the leading developers of the sash window for domestic properties. They had been around for a long time but only in grander places mostly with high ceilings and they were both simple and draughty. The Victorians improved the construction of wooden sash windows which were particularly beneficial alongside the other Victorian introduction – gas lighting. When fully closed and with the sash fastener on the meeting rails tightened, a well-made sash window was virtually draught-proof, but by opening the window by a couple of inches at the top and bottom a flow of air was provided that would remove stale smells [coal fires, candles, and gas lighting among others] and let in outside air [which admittedly was not of the purest in industrial districts]. Cool air would enter at the bottom of the window and hot air would escape from the top opening. The improved ventilation of houses and enforced standards of building separation to admit more air and light were two of the main contributors to public health and the lowering of infant mortality rates. Unfortunately the Victorians were using some fairly gruesome compounds for daily domestic tasks and I was reading recently about the widespread use of arsenic in interior decorations, especially wallpapers, that was never prohibited; the manufacturers just stopped using it when other chemical dyes became available in the latter part of the nineteenth century but arsenic was still in use into the twentieth century. I think we have come a long way since then but we have to be constantly on the look-out for modern chemicals that are being sneakily introduced into our homes, largely on the back of cunning advertising and marketing ploys. The Victorians also came up with carbolic soap [Lifebuoy among others] which had antiseptic properties but could also irritate the skin; this was considered to be virtuous and a sign of its efficacy!

Beryl – I believe the use of vinyl chloride as a propellant in hairspray etc was banned in the 1970s, and not before time.

Methylene chloride (dichloromethane) is a solvent rather than a propellant and I’m not sure when this disappeared from household products. In recent years it has been removed from paint and varnish removers, though it is still available online.

As you say, ‘fragrances’ are not identified, and that must change.

I stand corrected I should have written “ingredients are not always listed”. Having just checked the list of ingredients on my aerosol can of hairspray they read as follows:

Alcohol, Denat, Dimethyl Ether, Aqua/water, Polyurethane, Dimethicone, Glycerin, Hydroxycitronellal, Limonene, Alpha-Isomethyl, Ionone, Argania Spinosa oil/Argania Spinosa Kernel Oil, Coumarin, Linalool, Citronellol, Benzl Alcohol, Geraniol, Benzyl Benzoate, Amyl Cinnamal, Parfumerie/Fragrance, (F.I.L C170584/1).

Apart from the obvious highly inflammable, can anyone translate into which ingredients are potentially harmful/unharmful?

And I should have written: ‘… fragrances are not always identified…’ I suspect FIL relates to the US Fragrance Ingredients List.

Many household and gardening chemicals have been banned since I studied chemistry at university and it is difficult to know which ones are safe. Our hair is dead but many chemicals can penetrate the thin skin on the scalp and as we are discussing, we can inhale them. I hope there are simpler products available.

The perfume is the worst in my experience but a lot of these are nasties for me. Why not try, “Green People” products or “Home Scents”.

I agree with a lot of what you say. I use, “Green People”, “Home Scents”, “Healthy House” and “Ecos/ Lakeland organic Paint.” That way I don’t fill my house and body with VOCs and petro chemical pollution.

Most of these modern scents are just artificial chemicals that you don’t need. If you can tolerate them, fine, but many people find respiratory tract symptoms of post-nasal drip, asthma, emphysema, etc are improved without these unnecessary chemicals in their lives.

JMM says:
13 April 2017

If you can tolerate them, fine – but the person sitting next to you on the bus, or in the cinema, or even round your kitchen table, while the scent wafts off you hair, or your clothes, may be unable to tolerate them. They are all unnecessary – please, just avoid.

What is the smell that you get after opening a glossy magazine that has been wrapped in a plastic “envelope”? Is it a voc from the ink?
It seems to give me a temporary headache, although that might be psychosomatic!

Really glossy magazines have laminated covers which could also be releasing vapours, as could the plastic envelope itself. Best avoided – stick to Private Eye from a newsstand. Can still make you feel sick though . . .

I have mentioned before the use of mechanical air exchangers to keep air fresh in a property and also allow the extraction of heat to warm the replacement fresh air. I hope that Which? covers this aspect in its forthcoming report – but I fear disappointment.

The general recommendation is four exchanges an hour but with heating costs most people live in a fug. There has been plenty of research on the subject and it is a shame the subject is so rarely “aired”. The other point is that stale air is also often moisture laden which leads to other problems in the home.

Apropos bathrooms VentAxia [and probably others] for the last twenty years have sold extractor fans controlled by humidistats which continue to extract until the desired moisture level is reached in the bathroom. And it could equally well be used in a kitchen. One wonders why it is not in Building Regs as the dangers of mould and the damage of condensation are hardly new.

I am interested in your last paragraph, Patrick, as I had not heard of that before. It seems like it should be an essential provision. Many people seem to have isolated their extractor fans in bathrooms, shower rooms and toilets because they don’t like the noise! In any case they only seem to run for a few minutes after the light is switched off and certainly are not effective in clearing the room of moisture or domestic pollution especially if the door is left open because that will short-circuit the air exchange. In such rooms with daylight, if the light is not switched on, there is no air change at all. Where a toilet is adjacent to a kitchen with no intervening compartment the building regulations require a powerful extractor to be installed that will run for at least fifteen minutes after the light is switched off [but if there is no need to switch the light on the extractor is not activated – perhaps it should be interlocked with the door latch or linked to a motion sensor (no pun intended)]. There is no such requirement for other bathrooms etc.

“linked to a motion sensor”… Wonderful!

On a slightly more serious note we have a full air conditioning system installed here, which cleans, humidifies (or de-humidifies) the air as appropriate, and heats or cools the air on demand. It became necessary because our lounge and dining rooms overlook the Snowdonia Carneddau range and the sun sets opposite during the summer months, turning the rooms into fair imitations of a microwave oven. The interesting bit is the total cost, including installation, came to a lot less than new double glazing. And the heating effect through heat-pump technology affords us 2.5kw of heating for .5kw of electricity.

As Patrick says, this is something worthy of attention from Which?

Good point. Many years ago I had a loft fan fitted as an effective treatment for slightly elevated Radon levels (I live in Cornwall). I believe these products were originally designed to combat condensation in new-build properties, but it had the added benefit of making the house much healthier and fresher. The loft fan essentially brings in outside air via the loft space, and runs continuously, so if you have high external pollution levels it might not be such a good idea. It consumes very little electricity – a few watts. More recently I’ve added a fan that automatically circulates the heat from the conservatory into the living room, which has a similar effect. When the jasmine is flowering the scent is spread through the entire house – but maybe that counts as another pollutant!

There is a UK site that compares three of those available – and for those unfamiliar with them this is the salient point:

” Featuring the somewhat standard 60% to 90% adjustable humidistat this is a great little fan, however for just an extra twenty pound or so you could get the XXXXX above which is truly an impressive fan.”

Fans can/ will run on until that point you desired is reached. Simple and for some unknown reason too much a secret. As I believe in educating the buying public I am a bit miffed that there is no easy unbiased resource.

Jeff Howells recently dropped from the Telegraph has bee a font of wisdom over the years and if Which? had any sense they would hire him to bolster a major weakness in the offering.

Anyway a little bit of advice ” fans mounted in plasterboard ceilings or stud partition walls can seem excessively noisy, because these act as sounding boards. It is better to mount a fan directly through an outside masonry wall, where possible, or in the case of an upstairs bathroom, to have an “in-line” fan fixed to a rafter or other roof timber, connected by flexible ducting to the ceiling inlet and roof outlet.

” You can use a dehumidifier when you notice signs of damp, such as condensation on your windows. But it should be the last measure you take to tackle excess moisture. Taking these simple steps can help to reduce your reliance on a dehumidifier: Use an extractor fan or open a window when taking a bath or shower.”

Read more: http://www.which.co.uk/reviews/dehumidifiers/article/dehumidifiers-explained – Which?

You might well think that in this recent article that Which? would have mentioned that installing a humidistat extractor fan would be far cheaper and more logical than buying a dehumidifier. Certainly in an article on dampness in homes this would have been one of my first suggestions.

I enjoyed his column immensely. How about a Jeff Howells appreciation society 🙂

I have a small indoor ‘garden’ as I’ve heard that plants help to clean the air.

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Certain plants can extract VOC’s from the air and that is irrelevant to the CO side. This recent scientific paper is useful:

” The researchers tested five common house plants and eight common VOCs, and they found that certain plants were better at absorbing specific compounds. For example, all five plants could remove acetone — the pungent chemical that is abundant at nail salons — from the air, but the dracaena plant took up the most, around 94 percent of the chemical.

“Based on our results, we can recommend what plants are good for certain types of VOCs and for specific locations,” Niri says. “To illustrate, the bromeliad plant was very good at removing six out of eight studied VOCs — it was able to take up more than 80 percent of each of those compounds — over the twelve-hour sampling period. So it could be a good plant to have sitting around in the household or workplace.”

Your printed copy article on this included wood burners on the list of pollution generators. People have been burning wood, coal and heaven knows what else in open fires for generations without noting ill effects. I live in a ‘draughty Victorian house’ (but less so now it has secondary glazing) with a solid fuel central heating system. My living room is two smaller rooms knocked into one – so there are two fireplaces at opposite ends. One has the fire/boiler and I had the other stopped up over 40 years ago, ensuring its chimney was properly swept and a large air-brick installed to give it ventilation – and also to ensure a supply of air for the room heater. So the fire provides cross-flow ventilation by drawing air down the redundant chimney – and all the ‘nasties’ go up its own chimney. Not that they are particularly nasty – I ensure it’s good and hot before burning ‘tree’ wood – until it is, I burn used wood, and anthracite at night to keep it in. Air is always fresh – and yes – I don’t allow anyone to smoke cigarettes etc. indoors.

Steve: I spent a huge part of my youth camping and cooking on wood fires. I loved bonfires and had coal fires in most of the houses I’ve lived in. But New Scientist has been publishing research which suggests burning wood on fires is only marginally better than shooting yourself.


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John says:
26 March 2017

My house has a damp problem and despite some thorough cleaning I always smell mould (or mildew) when I come into the house. Recently, after a bout of flu, I have had a persistent cough which has been going on now for nearly a month. I can’t help feeling the mould is, at least partly, to blame.

I’ve just joined Which? in order to research air purifiers. Can anyone recommend a good way to deal with mould, and has anyone had experience of an air purifier they trust? Thanks.

Hi John,
Welcome to Which. If you register and log in, you will be able to keep track of any replies you might get.

You might like to have a look at Mould Allergy Advice here:

There are air purifiers for mould, but they don’t remove excess moisture in the air. You might want to check out dehumidifiers with HEPA air filters as they might be what you need.

I have a Daikin air purifier (at least 8 years old) to help with hay fever in the summer. I also have a Mitsubishi MJ-E16VX (at least 8 years old now) bought to dry laundry, but works very well at removing excess moisture from a room.

If buying a dehumidifier, it is worth checking water collection rate and the size of the collection tank as some of them are quite small and was the main reason I decided on the Mitsubishi.

If you look at the “Healthy House” website or phone them to ask advice they have been helping people for many years. A Which recommended “Maeco” dehumidifier is very useful for removing moisture from rooms especially in the winter when outside humidity may be 90%. Cooking, breathing, showering and drying washing indoors creates a lot of moisture and heating moist air is more costly, so a dehumidifier can pay for itself in lower heating costs. (John Lewis and Amazon sell these too). Again “Healthy House” tried and tested air purifiers work and help combat moulds, chemicals etc. Ecos/Lakeland paints are solvent free, organic paints and have different solutions to help this problem without creating pollution! Ask these people they have been researching and helping people for years. Get rid of your gass cooker if you have one. Good Luck.

I’m pleased that Which? has finally got round to producing an article on ‘nasties’ in the indoor environment – I’ve sent letters and emails several times to Which?, over many years, suggesting the need for research and articles on this subject.

A few years ago, ‘The Ecologist’ magazine published a series of articles, looking at the ingredients list of a number of household products including, as far as I recall, cleaning and toiletry items, together with some cosmetic products. The results were horrifying, as many of them included actual or suspected carcinogens, toxins, central nervous system disruptors, skin penetrators and allergens. I recall that at least some of these were present merely to extend the shelf life of the products.

Since then, I’ve tried to keep well clear of perfumed products (e.g. soap and washing powder), when I can, and I don’t use air fresheners – as a Scot, I obviously prefer opening a window, as it’s free!

It would be helpful if, when publishing product reviews in future, Which? would take up my previous suggestion of listing known harmful products contained in the products tested. If consumers are unaware of their presence, many manufacturers will continue to get away with selling potentially harmful products, rather than being shamed into altering them, for the benefit of consumers’ health.

Unfortunately for many household products the proportion of ingredients by volume is not stated so it is impossible to assess how much influence they might have on the atmosphere or our health. Most of them are unnecessary. The amazing thing is how sales hold up even during what commentators describe as a sharp recession and period of extreme austerity. Either the products are essential for people’s lives or the marketing is extremely good. Many people on limited budgets are persuaded to buy them when fresh air, soap and water, and simpler products would be just as effective. There’s often some boiled water left in the kettle after making a cuppa; put a little household soda in the plughole and pour the water in slowly. Do it frequently and there’ll be no more need for expensive drain unblocking products with all their heavy chemicals.

Thank you Which magazine for a balanced view from a well respected source. I have a friend who has suffered from, “multiple chemical sensitivity” for about 25 years. In its extreme form it is totally debilitating. While this problem is not generally recognised in Britain it is recognised in Canada and the USA. It is recognised there that people have a right to breathe clean air and so there is legislation to protect them when using taxis, public buildings, schools etc. I would like it if Which magazine could do more research to learn what they know and inform the British public. I am aware that some work places ask staff not to use certain personal chemical products such as, perfumes and deodorants, as these trigger asthma in sensitive individuals.
While you give people advice on what not to use, am I allowed to name companies that produce products without solvents, VOCs and petro chemicals that pollute the home?

Helen says:
6 April 2017

Hi this is great that Which are looking at this problem. I work at MCS-Aware, a registered charity in the UK and we help support people who are ill from environmental pollutants. We are seeing an increase in health problems due to indoor pollutants. MCS or Multiple Chemical Sensitivity is recognised in many countries as an illness but not in the UK. Besides reacting to things like cleaning products, shampoo, perfumes and pesticides, many sufferers are also sensitive to food, medicines, moulds and electromagnetic fields.

[Sorry, we don’t allow promotional material on Which? Conversation. Please check out our Community Guidelines for more info. Thanks, mods]

I don’t see any reference to possible pollution from domestic Oil Fired boilers? They use similar fuel oil like diesel and presumably spew out particulates too.
In Suffolk the most common form of heating seems to be oil fired boilers.
Are there any statistics available for comparison?

Increasing ventilation is the complete opposite of what we are advised to do to save energy and protect the environment from the adverse effects of rising carbon dioxide levels. As Patrick Taylor has pointed out, the solution would be to use ventilation fans with heat exchangers, but these seem to be rarely used. I would like to add my voice to his in calling for a Which? report on such devices to raise awareness of them.

Thanks for the support Mike. It does seem daft that with all the emphasis on insulating, and fuel poverty, such an important matter has been missed for so long.

Unfortunately I think that the outsourced testing has lead to a heavy concentration on consumer electronics and very little on more expensive items that consumers buy for the long term. Which? seems to shy away from these matters. Worktops spring to mind as a common item that Which? has not dealt with.

Choice, the small but very active Australian consumer group, did a review of all the materials for worktops last year. I wonder if the readership could easily turn to an evaluation here in the UK of the dozen alternatives.

I realise that a Best Buy label could hardly be awarded but educating consumers is part of the Articles of the charity.

Did you know that this was covered in the BBC series, Trust me I’m a doctor – web page – http://www.bbc.co.uk/programmes/articles/1yGxPx6ljN6GxNCkmNkwmF9/how-does-air-pollution-affect-us
This came up with some very interesting facts and figures (for both outside and inside pollution) and also gave a list of plants which you could buy for your home to reduce formaldehyde (one of the more common indoor pollutants, also very toxic) :- Chlorophytum (Spider plant), Dracaena (Dragon tree), Scindapsus (Golden Pothos), Hedera helix (English Ivy).
The results of our very small experiment suggest that the plants could have played a role in reducing the levels of formaldehyde in our families’ homes.
One study in 2010 tested 86 species of plant for their effectiveness in absorbing formaldehyde, and found 9 to be excellent absorbers:
• Osmunda japonica (Japanese royal fern)
• Selaginella tamariscina
• Davallia mariesii (squirrel’s foot fern)
• Polypodium formosanum (grub fern)
• Psidium guajava (common guava)
• Lavandula spp (lavender)
• Pteris dispar
• Pteris multifida (spider fern)
• Pelagonium spp. (geranium)
Other studies have looked at a wider range of chemicals, and house plant species which have excellent all-round absorbing ability seem to be:
• Hemigraphis alternate
• Hedera helix (English ivy)
We have an air purifier for upstairs and one for downstairs because I have asthma and my husband suffers from bronchiectasis, we have found them very helpful. We also sleep with the window open at night – whatever the weather!
We have no air fresheners whatsoever.

JMM says:
13 April 2017

I saw the BBC “Trust me I’m a doctor” programme too and suddenly understood why even Ecover cleaning products made me cough. Limonene is in effect formaldehyde, not a nice squeeze of lemon juice for the scent. (I think Ecover is no longer the really green operation it was when it first launched, and is much more likely to contain VOCs and other industrial ingredients as it’s now part of some large conglomerate, but I may have misremembered the take-over – it was a long time ago.) One house, where the owners sprayed “air freshener” over everything (including the dog) umpteen times a day, was found to have astonishing levels of chemical contaminants. Have houseplants by all means, but much better would be just to accept natural smells and natural ventilation. I do draw the line at a dog that’s just rolled in dead fox, though.
A lot of these issues could be covered by building regs and planning legislation, but all the move is away from control and towards whatever a developer wants to do. So a bathroom with an outside window is almost unheard of in new property. Flats have nowhere to dry washing, and airtight windows are deemed to be a good thing. My daughter’s rented ground-floor flat in London, built about 5 years ago, has only glazed doors to the bedroom, not a window. So getting any ventilation means leaving an outside door open. The window to the living room gives directly onto the street, so is not good to leave open if there’s no-one home. That design detail should never have got through building regs. Ceiling heights are too low and rooms sizes too small – the smallest in Europe – so the same amount of indoor air pollution is concentrated. The Victorians believed in fresh air and through draughts because they thought disease was caused by miasma (i.e. was spread on the air). Even when they realised germs were spread by human contact, and Dr John Snow discovered that cholera was in fact spread by water, even modest houses were still built with large windows and decent ceiling heights. A modern airtight home may help with fuel poverty, but if the occupier is made ill by the combination of mould and indoor chemicals, that’s no economy.

julian williams says:
4 April 2018

I think that ventilation has a highly underrated influence on our daily lives. In my line of work I see plenty of people who live in homes with damp and mould. One of my tasks is to advise on remedies and another is to advise on energy efficiency. When people are replacing older windows with new double glazing, I think that it is an enormous mistake for Building Regulations to allow a choice of ‘with trickle vents’ or ‘without trickle vents’, based upon whether or not trickle vents were there before. The fact is that older windows, including Victorian sashes, were ‘leaky’ and this, in effect, allowed ‘trickle ventilation’. Reducing this basic necessity makes living conditions worse. Very many people simply do not understand that a home sealed from draughts and fresh air is going to become humid and damp, because of the many sources of evaporating moisture inside: boiling a kettle, breathing, cooking, showering, running a tap, bathing, mopping a floor, washing up and so forth. Now to prevent damp and mould developing in the first place, where the cause is NOT from ‘external influences’ (such as leaks, rainwater or rising damp, for instance) you need good insulation, good ventilation and some heating. A highly insulated home needs no ‘heating system’ because the ‘heat’ comes from human bodies, the lighting and the ‘machines’ we operate inside, including computers. But we always need ventilation. One common reason that people have damp and mould is due to condensation – either on the inside of windows (single-glazing or low-quality double glazing) or on walls, ceilings and even floors. When double glazing unit ‘seals’ fail, you see ‘interstitial’ condensation between the panes of glass. Many people do not have enough money to add insulation to their walls, floors and roofs. Unfortunately, when the temperature outside is cold, the temptation inside is to keep all of the windows closed and very many people do not have trickle vents in their double glazing, so a build-up of stale, humid air is inevitable. Furthermore, many people not have effective working extract fans in bathrooms and kitchens, or they find them so noisy, or believe that they are expensive to run, that they don’t use them. Some people have extract fans and draught proofing but no trickle vents (to readily supply the fresh air to replace the stale air extracted. Many people do not realise that a poorly ventilated home is often a damp home, because the ‘humidity’ has to go somewhere – so it is absorbed by the fabric of the building (plaster, brickwork, wood, furnishings, etc. A humid home is harder to heat than a dry one, because it takes extra energy to evaporate the moisture. Therefore opening windows sufficiently for fresh air (not a breeze), even during colder weather, helps maintain not just healthy internal air quality but also a more reasonable temperature by keeping humidity lower. Humans can tolerate humidity levels of 40-60% (what is called ‘relative humidity’) – higher or lower than this range eventually gives us problems. One result of poor ventilation is that people – especially the old and the young – get sick, take time off work, spend time in hospital, develop long term health problems and even die, due to breathing difficulties and severe lung problems. My personal view is that domestic ventilation is a critically important issue which receives a relatively miniscule amount of Press attention, especially within existing homes. Poor ventilation, ‘condensation damp’ and mould seems to me to be worse in low income homes and in rented properties. I think this is a blind spot that Which? should be helping to draw attention to. My online Which? search today (04/04/2018) revealed only seven Which? tests on cooker hoods (most over ten years old) and none on bathroom or WC extract fans, or even kitchen extract fans (for where a hood is impossible). BTW, because ‘recirculation’ fans simply throw greasy, humid, CO2-laden stale air around the kitchen, my personal view is that they should be banned altogether.
I believe that all extract fans should be suitably quiet, efficient to run, easy to control and have optional sensors included, such as humidity and carbon dioxide, so that they work according to need. These are all aspects which affect our health and our monthly expenditure.
Come on guys and girls – please try harder!

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Paul says:
4 June 2018

In France, modern houses are required to have a ‘VMC’ (ventilation mécanique contrôlée). This normally consists of a single fan unit that extracts air from wet rooms via tubes. All other rooms are fitted with trickle vents to allow a controlled flow of incoming air. The system consumes very little energy – the fan is usually rated at approx 40W, and is very effective. A whole system can cost as littme as €100. More sophisticated versions have controls to boost manually the air flow or automatically using an humidistat. The most sophisticated, ‘VMC double flux’, use a heat exchanger and two fans to provide both extract from wet rooms and inflow for the other rooms. This system does not need trickle vents and recuperates heat from the extracted air to incoming fresh air. Some systems claim 90% efficiency for heat recuperation. These systems are very quiet and, in most cases, not difficult to fit. Why don’t we have systems like this in UK?

We do. MVHR units and MEV’s. Google the acronyms.

Paul says:
4 June 2018

OK, but nearly all houses (even older refurbished ones) in France have this system. What percentage in UK?

MVHR (mechanical ventilation with heat recovery) systems are very common in non-domestic applications in the UK, where they can be used to provide heating and cooling as well as fresh air. In domestic use, the power consumption of the fans is likely to be small compared with the loss of heat from rooms because the heat exchanger is not (and cannot be) 100% effective at transferring heat from outgoing warm air to incoming cold air. That will be less of a problem in a warmer climate.

Here’s a Which? assessment of a gadget to measure air pollution – https://www.which.co.uk/news/2019/10/my-week-with-the-atmotube-pro-air-quality-monitor/
No mention of whether it is accurate in its measurement. It may be enough to know when the air is polluted or not, but giving true readings is important.

One conclusion seems to be Which?, for the benefit of its staff, should move “I can’t change the fact that my office is on a polluted street,“. Along with many other organisations. Cutting down on commuting and polluting seems the best way forward.