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Aerosol spread

  • 05-12-2020 7:21pm
    #1
    Registered Users Posts: 187 ✭✭ rahmalec


    I’m wondering, why has aerosol spread not been taken seriously as probably the main way, or at least one of the main ways this thing spreads. It seems only recently the world is catching on but there was clear evidence from early on for aerosol transmission, especially in situations where the amount of virus in the air can build over time to infectious doses regardless of social distancing. I’m thinking of situations like:
    - that choir rehearsal where one or two people infected pretty much the entire choir of 50 people
    - that bus where people all over the bus got infected from one person

    This being a main factor would explain a lot such as:
    - the meat plants. People working in one place in close contact for a long time.
    - why supermarkets were never a significant source or spread. People are generally in and out of such a space in a short time, so unless a staff member is infected, then the virus wouldn’t have enough time to build up in the room, plus supermarkets are usually big spaces with tall ceilings.
    - the spread in house meetings. A small space. Probably much risk if the person living in the house was infected vs a visitor, as plenty of virus would already be in the air.
    - the spread in office settings. Again, similar to households. Crazy that only now they’re recommending mask wearing in offices.

    It seems to me that a lot could be achieved not by closing everything, but that any indoor spaces including pubs and restaurants, etc, would have to keep doors and windows open.


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Comments

  • Moderators, Sports Moderators Posts: 11,205 Mod ✭✭✭✭ hmmm


    If I could give this a thousand likes I would. I don't understand it at all. It's clear as day where superspread events happen.


  • Registered Users Posts: 2,443 ✭✭✭ Tork


    The message definitely got lost early on and now the anti mask movement has become a vehicle for all sorts of cranks to stick it to the man. I'm just waiting for the usual suspects to seize on this thread and tell us that masks don't work, you'll collapse from inhaling your own CO2, how come the rates went up once masks became mandatory etc.


  • Registered Users Posts: 116 ✭✭ Solli


    I heard Prof Orla Hegarty UCD and Prof John Wenger UCC on the Claire Byrne radio program this week. It’s worth listening to this piece https://bit.ly/3lKVNy9
    They were presenting a webinar which I also listened to. It’s excellent, can post the link. And I cancelled my restaurant booking.


  • Registered Users Posts: 4,706 ✭✭✭ CalamariFritti


    Tork wrote: »
    The message definitely got lost early on and now the anti mask movement has become a vehicle for all sorts of cranks to stick it to the man. I'm just waiting for the usual suspects to seize on this thread and tell us that masks don't work, you'll collapse from inhaling your own CO2, how come the rates went up once masks became mandatory etc.

    To be fair the smaller the things are that cause the spread the less sense a mask makes.


  • Closed Accounts Posts: 59 ✭✭✭ BurgundyRose


    I'm appalled this isn't in the news more and highlighted more. We are still not over this pandemic and social distancing will be here to remain for more months. Even when vaccinations begin, we still won't be entirely safe yet because vaccinations are a 2 step process with 3 or 4 weeks in between shots. I was pub/restaurant for breakfast this morning and all I could do was hope and pray there was nobody infectious in my spot before me or the night before. There was no window open. Very poor. I wanted to leave but my boyfriend stopped me. It was also wet outside so we couldn't eat outside. I won't be going back there again.


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  • Registered Users Posts: 639 ✭✭✭ Thats me


    rahmalec wrote: »
    I’m wondering, why has aerosol spread not been taken seriously


    Good morning, it is 9 (nine) months while you being said to wear a mask and avoind non-necessary travels and visiting public places :D


  • Banned (with Prison Access) Posts: 4,077 ✭✭✭ Away With The Fairies


    I see so much city buses pass me and I notice foggy windows and no window open. Very dangerous using buses.

    Can't believe a public transport company isn't doing much but I can't really blame them when they are following the HSE guidelines which is all about distancing. There should be more emphasis on opening windows.


  • Registered Users Posts: 9,149 ✭✭✭ normanoffside


    I see so much city buses pass me and I notice foggy windows and no window open. Very dangerous using buses.

    Can't believe a public transport company isn't doing much but I can't really blame them when they are following the HSE guidelines which is all about distancing. There should be more emphasis on opening windows.

    All the Dublinbus windows have signs on them saying they must be kept opened at all times. That said, in the past week most of them have been closed.


  • Banned (with Prison Access) Posts: 4,077 ✭✭✭ Away With The Fairies


    All the Dublinbus windows have signs on them saying they must be kept opened at all times. That said, in the past week most of them have been closed.

    I haven't used a bus since all this kicked off, so don't know what kind of signs or measures have been implemented on buses. I just say what I see and no open windows.


  • Closed Accounts Posts: 423 ✭✭ AutoTuning


    The main reason is there’s apparently no building services engineering / HVAC (heating, ventilation and air conditioning) experts on NPHET and we typically have very little expertise in this area in general, due to the relatively mild climate. Most Irish buildings have windows, not ventilation.

    Our trains and trams, many offices, universities (at least parts of them) big shops and shopping centres have air handling or air conditioning, but that’s about it.

    Schools in general, for example, are heated like houses, with radiators. It would be highly unusual to have any kind of air handling. That’s due to the climate and is similar across all much of Europe.

    At the very least, we should probably installing large extractor fans in the windows of every classroom and restaurant to maximise air changes.

    The other aspect is it would breech building regulations and put out energy use way up, which is also probably serving as a barrier to doing anything. To do this efficiently actually requires sophisticated air handling with heat exchangers. Otherwise, you’re just pulling heated air out of the building.


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  • Registered Users Posts: 17,886 ✭✭✭✭ Del2005


    I see so much city buses pass me and I notice foggy windows and no window open. Very dangerous using buses.

    Can't believe a public transport company isn't doing much but I can't really blame them when they are following the HSE guidelines which is all about distancing. There should be more emphasis on opening windows.

    People keep closing them on buses and trams. The companies should make it so that the windows can't be closed on public transport that has windows that open and increase the air flow on public transport which doesn't have windows that can be opened


  • Closed Accounts Posts: 423 ✭✭ AutoTuning


    They just need to put stickers on them - COVID-19 ventilation. Do not close.

    People in Ireland can be weird about closing absolutely every window and nearly suffocating the room. There an element of society here that has an absolute paranoia about draughts and seems to think “you’ll catch your death” from mildly cool breezes, when in reality all colds, flus and now COVID 19 are caused by viruses, not slight breezes on your neck.

    I remember in both secondary school and university, classrooms that were so stuffy I would nearly be passing out due to lack of oxygen and if you opened them window you’d have either a colleague in university giving out about how there’s a draught, or a teacher sitting there in school with a jumper and about 2 scarves even though it was 25° absolutely point blank refusing my 10th request to open the window!!

    I’ve also always found, especially this time of year, both in Ireland and the U.K., most retail is unbearably hot ans stuffy. You walk into a shop, you’re in a big coat and the shop staff are wearing t shirts and it’s like 23°C or more.

    It’s one of my pet hates about shopping here in winter but, it’s worse when you consider those same habits are probably making those places much less safe than they could be.

    The other big danger I saw this summer was inappropriate use of air conditioning that has 100% recirculation. I don’t mean big air handling systems, but the cassette air conditioners that you find in a lot of cafes and so on. They just pull air in, cool it, dehumidify it, perhaps pass it through a simple fluff filter (similar to on a tumble dryer for keeping fluff out of the fans and evaporator) and return it to the room. There’s no fresh air intake or foul air outlet to outside.

    I walked out of a coffee shop earlier in the year that had that system on full blast. The air was cool & dehumidified but you could smell the mustiness of the recirculated chilled air and it would undoubtedly be excellent for maximising coronavirus exposure.


  • Registered Users Posts: 639 ✭✭✭ Thats me


    AutoTuning wrote: »
    They just need to put stickers on them - COVID-19 ventilation. Do not close.


    Open windows do interfere with conditioning system.


  • Closed Accounts Posts: 423 ✭✭ AutoTuning


    Thats me wrote: »
    Open windows do interfere with conditioning system.

    There is no air conditioning system on any bus or train here that has opening windows. They just have fans and heaters.

    There’s full air conditioning on all Irish intercity trains, and only some commuter and DART trains. Openable windows indicates no air conditioning.

    No city busses in the Dublin Bus or other cities’ Bus Éireann fleets have air conditioning, nor does the Luas. That’s just air circulation from fans. The city busses barely even have fans, which is why the windows steam up. They’re very, very basic.

    The same applies in the U.K. busses generally don’t have air conditioning and there’s absolutely none on the Tube.


  • Registered Users Posts: 2,576 ✭✭✭ mr_edge_to_you


    While out and about in recent days in the cold weather, you see can obviously see your own breath as you exhale. It clearly shows how easy it is to spread any kind of a virus via aerosol. 2m us the minimum you need to be apart from anyone.


  • Closed Accounts Posts: 423 ✭✭ AutoTuning


    Think of it like cigarette smoke. If someone lights up in a closed room, you’ll have it in your hair, on your clothes and you’ll be passively smoking.

    You can smell the particles and volatiles from a cigarette, but they illustrate quite well how micro particles can spread in air, even when you can’t detect them with your nose.


  • Registered Users Posts: 3,818 ✭✭✭ Darc19


    I haven't used a bus since all this kicked off, so don't know what kind of signs or measures have been implemented on buses. I just say what I see and no open windows.

    So how can you comment on it if you haven't been on a bus?

    This shaming and blaming is a virus in itself.

    Utterly disgusting.


  • Banned (with Prison Access) Posts: 4,077 ✭✭✭ Away With The Fairies


    Darc19 wrote: »
    So how can you comment on it if you haven't been on a bus?

    This shaming and blaming is a virus in itself.

    Utterly disgusting.

    I see a passing bus and no open windows. I don't have to be on the bus to see with my own eyes.


  • Registered Users Posts: 1,388 ✭✭✭ VeVeX


    While out and about in recent days in the cold weather, you see can obviously see your own breath as you exhale. It clearly shows how easy it is to spread any kind of a virus via aerosol. 2m us the minimum you need to be apart from anyone.

    I often wonder how has the human race survived without a 2m distance between people.


  • Registered Users Posts: 42 Claiomh


    Good to see this finally getting more traction. It was already discussed in webinars and peer reviewed studies (Skagit Choir super-spreading event) back in August, but has taken ages to get into general society. If NPHET and Government talked more about it, it could help others understand what settings were reasonably safe or not (i.e pubs and restaurants with poor ventilation catering to groups staying for 90 minutes +, as opposed to even doing a weekly shop, and trust them to make decisions themselves. Outdoors is estimated to be 20 times safer than indoors, so let pubs and restaurants do outdoor dining and takeaway, but don't let indoor open without a proper ventilation system or procedure. Perspex screens are mostly ineffective window dressing and not anywhere near as useful as regular ventilation of space with fresh, humid air.


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  • Registered Users Posts: 11,504 ✭✭✭✭ Rjd2




  • Registered Users Posts: 8,519 ✭✭✭ igCorcaigh


    Droplets are the main way of spreading the virus, but aerosol transmission can occur sometimes.

    Viral load is a big factor on transmissibility, and this may vary due to the level of infection in a person, the environment, lots of factors.


  • Registered Users Posts: 8,519 ✭✭✭ igCorcaigh


    Rjd2 wrote: »

    True.

    "The takeaway is the same. Indoors, we should always wear a mask–there is no way to make indoor restaurants or bars safe, including those outside structures that are essentially indoor. Air flow and talking matter and, indoors, neither six feet nor 15 min are absolute protection."

    And I don't think indoor dining is safe.

    But we have to look at how this happens at scale.
    Some people are super spreaders because of how much virus they carry, and other reasons.

    There is a whole spectrum of risk, and it's not sound to model an isolated incident and project that to a population level.


  • Registered Users Posts: 31,701 ✭✭✭✭ is_that_so


    Rjd2 wrote: »
    Sounds like she just wants to close bars and restaurants permanently. It also depends on what overall transmission rates are like and how infectious people are at that time. What we have learnt about COVID is our behaviour is a huge factor in how it spreads and locations are just a part of the equation.


  • Registered Users Posts: 639 ✭✭✭ Thats me


    is_that_so wrote: »
    Sounds like she just wants to close bars and restaurants permanently. It also depends on what overall transmission rates are like and how infectious people are at that time. What we have learnt about COVID is our behaviour is a huge factor in how it spreads and locations are just a part of the equation.


    Need to remember it is not only covid spreading this way. As many times pointed by covid-deniers brigade, even influenza has same fatality rate and can lead to serious side effects. And all these viruses are being spread same way. Therefore i think it would be smart move if some measures in public places would persist past covid epidemic. I mean proper ventilation everywhere, comfortable one-way traffic in the shops, space between tables in pubs and restaurants, touchless systems everywhere, starting from the toilet door in the pub etc.


  • Banned (with Prison Access) Posts: 4,077 ✭✭✭ Away With The Fairies


    The WHO and CDC has guidance on protecting each other from covid. Both sites mention opening windows for ventilation. The HSE has it under the section of how to stay safe this Christmas.

    Eh, how about how to stay safe all the time, not just Christmas?

    Wonder will they pull the finger out with this new strain in the UK (it's probably already here). This new strain is more contagious and there should be more on ventilation than what there is.


  • Registered Users Posts: 639 ✭✭✭ Thats me


    Eh, how about how to stay safe all the time, not just Christmas?


    "Après moi, le déluge" - Santa said.


  • Registered Users Posts: 8,281 ✭✭✭ PlentyOhToole


    Our local church has a ticketing system for mass on Christmas Day- I got 4 tickets, 2 of those were for elderly people.
    I then went home and had a long think about it- there would be 3 masses before us- while I know the social distancing in the church and the sanitation regime would be excellent- it was the thought of 3 masses worth droplets in the air- it would have been criminal for me to place vulnerable people, no less myself into that environment- I handed the tickets back the following day-
    I was so caught up in maintaining their tradition of Christmas mass that it took a while for me to think straight-


  • Registered Users Posts: 14,744 ✭✭✭✭ astrofool


    Our local church has a ticketing system for mass on Christmas Day- I got 4 tickets, 2 of those were for elderly people.
    I then went home and had a long think about it- there would be 3 masses before us- while I know the social distancing in the church and the sanitation regime would be excellent- it was the thought of 3 masses worth droplets in the air- it would have been criminal for me to place vulnerable people, no less myself into that environment- I handed the tickets back the following day-
    I was so caught up in maintaining their tradition of Christmas mass that it took a while for me to think straight-

    Given the average age profile of those who attend mass, it's probably sinful for them still to be going ahead in person.


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  • Registered Users Posts: 7,641 ✭✭✭ BrianD3


    Right from the start of this pandemic there was far too much emphasis on handwashing and surfaces and not enough on the fact that it is a respiratory virus spread by coughing, sneezing, talking, breathing into the air.. I remember thinking this at the start when I cleared the local hardware shops of FFP2 and FFP3 respirators for myself and the staff in work. Around the same time I saw a youtube video where an infectious diseases expert said something along the lines of handwashing etc. might prevent about 10% of cases.

    Subsequently we went into lockdown/WFH and by the summer employees were being pressured to return to poorly ventilated offices - but it was fine as long as they were more than the magic 2 metres apart and less than the magic 15 minutes together. However if they were handling a file or document in said office, H&S procedures required them to sanitise their hands before and after it, each time. There was also mention of microwaving post before handling it :rolleyes:


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