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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentTimeAug 31st 2021 edited

    "The airborne compounds are thought to break off of PFAS-treated products such as carpeting and clothing and attach to dust or freely float through the indoor environment.

    Experts previously considered food and water to be the two main routes by which humans are exposed to PFAS, but the study’s ... findings suggest that breathing in the chemicals probably represents a third significant exposure route."

    Who'd a' guessed?

    "Also notable are the types of PFAS that the study detected. Among the most prevalent was 6:2 FTOH, a compound used in floor waxes, stain guards and food packaging. Industry previously claimed that 6:2 FTOH was safe, but in May the Guardian revealed that two major PFAS producers had hidden studies that suggested that the compounds are highly toxic at low doses in lab animals and stay in animals’ bodies for much longer than was previously known.

    The new study also found high levels of 8:2 FTOH, a type of compound that major PFAS manufacturers in the US claimed to have phased out of production because it is so dangerous. Its presence suggests that not all companies have phased it out."
    You suggested this has some connection to MHRV - what connection is that? Nothing in the article about it that I could see?
    • CommentTimeAug 31st 2021
    MHRV excels at continuously removing the continual low-level (?) off-gassing from the numerous artificial materials - furnishings and contents - with which we fill our buildings - and of non-artificial materials too e.g. formaldehyde from natural timber. That's prob the prime reason (maybe more than CO2 dilution) that people report the 'mountain freshness' of their interiors, with MVHR.

    Of course, that 'freshness' is just the same toxic mix being sucked back in, just massively diluted. 'Dumping it outside' is still what modern society has complacently done with its wastes and toxins, causing the present crisis.
    Nothing like that in this research though. They studied environments such as Californian classrooms, university buildings, offices and shops, which all tend to be mechanically ventilated with high air change rates.

    They didn't report any study of higher or lower concentrations in settings with natural ventilation such as opening windows, or accidental ventilation such as drafts.

    They did suggest some correlation with the room being carpeted and full of people wearing clothes.

    The whole point of these chemicals is they are unreactive, and do not "off gas", they are used as replacement for cheaper chemical coatings which do. They also have nothing to do with formaldehyde.

    The research tentatively suggested that dust particles were breaking off the coated carpet and clothing fibres and getting blown into the air by circulating air currents, thus carrying the coatings into the air.

    They didn't suggest any solutions (other than ban the coatings and return to the less stable ones), but I would be looking at using uncarpeted flooring, and a vacuum cleaner, rather than mechanical ventilation which circulates air currents. Or nudity.

    Edit: for the record, there's absolutely no evidence here that our exposure to coating chemicals will be decreased to a safe level by: vacuum cleaners, bare floors, MHRV, open windows, nudity, injecting bleach or anything else.... the point of science is to try these things experimentally before using them as click bait headlines!
    • CommentAuthorrevor
    • CommentTimeAug 31st 2021
    In order to get any formaldehyde from timber it would need to be heated to 50 deg C and then would be in PPB the hazard albeit low will come from wood products such as MDF and plywood from the adhesives used but most of it comes off during manufacture of the board and during exposure when initial being used.
    We have no carpets in our house but our exhaust MVHR is "dirtier" than the inlet. Cause is fibres from towels I reckon, as the evidence is in exhaust air valve in the main bathroom. We often have countryside freshness air in the form of farm smells think I am more concerned what bacteria may be in it than what might gas off the timber in the house. We once did have a lot of issues from the spreading of digestate the stuff left over from anaerobic digestion of food waste, it often contained volatile fatty acids (VFA) which have some really nasty compounds in as result of poor processing.
    • CommentTimeAug 31st 2021
    Posted By: revorour exhaust MVHR is "dirtier" than the inlet

    Wow! Now that does surprise me. We clean our filters every three months (when the red light come on on the MVHR unit). Occasionally we don't need to do anything but most commonly we have to wash the intake filter because it's covered in dust from outside and sometimes insects (we live in the country). The exhaust filter is usually clean, but we typically wash it every second time out of an abundance of caution. There's a separate filter on the exhaust terminal in the kitchen, which does get dirty, but other than that the exhaust terminals are straight through. I occasionally check inside them and they always seem to be clean.

    We do have carpets. We clean the house weekly.
    • CommentTimeAug 31st 2021 edited
    Will, I wasn't doing a summary of the study, more to add weight to what we PH-aware chaps know - that MVHR sets out to tackle just this phenomenon of indoor toxics (in addition to indoor CO2 and fart removal).

    The study doesn't attempt to suggest remedies, not ventilation nor anything. And I know it doesn't mention formaldehyde, which is nevertheless present in interiors.

    Particles breaking off and being carried by airstream vs off-gassing makes little difference. Ventilation works by dilution mainly (unless it's a catering range or fume cupboard extract situation, where directional air velocity aims to exceed the speed of PVP-driven dispersal or dispersal by other air currents). Such dilution works equally for airborne particles and gases. Not to mention airborne Covid. It's not correct to think that (turbulent) ventilation airflow actually spreads the substance - think instead that it dilutes it.

    Your last para tries to set up straw-man criticism.

    Posted By: revorhazard albeit low will come from wood products such as MDF and plywood from the adhesives used
    Coillte's Irish timber gets made into Smartply MDF, just using its natural adhesive content, proudly 'without added formaldehyde' adhesives (unlike Sterling's Scottish timber/MDF). However they're careful not to claim zero formaldehyde, admitting that the wood chips alone still off-gas some formaldehyde.
    Tom, some people have health concerns about these chemicals. There's no clarity about what level in air might be safe or hazardous (ppm? ppb? less?) - so no indication as to how many ACH of dilution ventilation would be needed to move you from 'danger' to 'safety'. (1 ACH? 1000 ACH?)

    However keen everyone is on recovering heat, you can't just declare that MHRV will "rescue" people from ill health, without any shred of medical evidence that it gives sufficient dilution, where natural ventilation would not have done. Wishful thinking isn't sufficient. It's the same as those people who tout 'covid cures' that they genuinely wish would work, but without any evidence.

    What if someone had relied on what you said, and then they got sick?

    My last para of my previous post was added to make clear that I have no evidential basis for or against any of the possibilities I mentioned in my second-last para.

    Revor, I know what you mean about mountain fresh air quality! We shut off all our ventilation weekly, while our farm neighbours one side are spreading muck, or the folks on the other side are burning their polythene bale wrappers.
    • CommentTimeSep 1st 2021 edited
    Will, why put words I didn't say into my mouth, just to shoot them down. That's straw man stuff. I didn't
    Posted By: WillInAberdeendeclare that MHRV will "rescue" people from ill health
    but there's no doubt that MVHR acts very much in the right direction, evidence people's comments about 'mountain freshness' - the smells that some toxics, VOCs put into the interior, which are usually too weak to notice but are striking in their absence, with MHVR. And I made no comparison -
    Posted By: WillInAberdeenwhere natural ventilation would not have done
    in fact I say that natural ventilation can be just as or more effective than MVHR provided the occupants are committed fresh air fiends who systematically open windows for periods whatever the weather, much more than 'normal'.
    • CommentAuthorrevor
    • CommentTimeSep 1st 2021
    Posted By: WillInAberdeenor the folks on the other side are burning their polythene bale wrappers.

    Report them to environmental health it is illegal to do what they are doing.
    Posted By: revor
    Posted By: WillInAberdeenor the folks on the other side are burning their polythene bale wrappers.

    Report them to environmental health it is illegal to do what they are doing.

    Or given that you are neighbours first talk to them and suggest they put them into the recycle system as a better option than burning
    • CommentAuthorrevor
    • CommentTimeSep 2nd 2021
    Posted By: Peter_in_HungaryOr given that you are neighbours first talk to them and suggest they put them into the recycle system as a better option than burning

    That is a fair point depends on how you get on with the neighbour as to how they will respond. There are systems for disposal of such stuff problem is that they do not want to pay for it although my neighbouring farmers are pretty good at doing the job properly. Depending on the type of farming being carried out and what schemes they are members of e.g farm assured they get audited on their procedures on all sorts of stuff.
    Sadly, that set of neighbours are 'traditionalist farmers' and don't hold with newfangled nonsense such as recycling, or with 'incomers' moving in and then complaining about farming being noisy and smelly. I agree with them, only on the second point!

    It's well known round here that Environmental health aren't staffed on Sunday afternoons, so that's when farms do noisy/dirty things. These days I doubt they would turn out for a farm bonfire anyway.

    Actually, I'm more concerned about the slurry spreading on my other neighbour's land. It's completely legal and part of the circular system on their organic farm which relies on natural manure instead of petroleum-based fertilizers. But releases a lot of ammonia into the air, though invisible at source it will be photochemically converted into PM2.5s. As with many things, it's the visible pollution that catches peoples attention, but maybe the invisible stuff needs it more.

    They have invested in a modern dribble-bar spreader to reduce emissions, check those out!
    • CommentAuthorrevor
    • CommentTimeSep 3rd 2021
    Posted By: WillInAberdeenThey have invested in a modern dribble-bar spreader to reduce emissions, check those out!

    An improvement on this is the tailing shoe gear which injects the nutrient into the slots it makes in the ground.
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