Theaters thought to pose less covid risk than thought

[Mark Gulbrandsen]

Steve, A cheapo air flow meter would answer that, it is also how an HVAC tech would determine if your air handler is powerful enough for the finer mesh filters. The meter would also make it easy to determine when to change them.

[Steve Guttag]

The anemometer (which we have to measure exhaust on projectors) would give you a "number" but wouldn't tell you what the minimum flow you should see. As you go up in MERV, the flow is going to go down. One of my filters is in the ceiling for the 2nd floor...I always turn the fan on when I change it...makes it much easier to not have to hold the filter while closing the grill. I also have multi-speed fans so it is possible to increase the force there to overcome some degree of restriction. Where I have things right now, however seems to work REAL well in both filtration and air flow. There are a couple of things I'd like to change on the HVAC on the house to improve the return paths on the second floor. I settled on the Filtrete 1500s (MERV-12) through experimentation and looking at what they were catching over 3-months time. They seem to "fit" what the house is working with.

[Mark Gulbrandsen]

Just compare it to the airflow of your Merv 8 filter. I personally would not want to see more than a 10% difference. Expenses would start going up then, especially as the filter clogs. And merv 8 is even better than most people use.

[Gordon McLeod]

Years ago they used to put UV lamps and ozinators in theatre's air handlers to sterilize the air hospitals also used to have those

[Marcel Birgelen]

Just compare it to the airflow of yoyr Merv 8 filter. I personally would not want to see more than a 10% difference. Expenses would start going up then, especially as the filter clogs. And merv 8 is even better than most people use.

We have discussed this with the local health authorities. They're against anything that produces ozon, as many people are quite susceptible to higher than normal ozon concentrations. They're not against UV lamps, but you can't legally sell it as a solution against coronavirus, because the effectiveness of it hasn't really been proven.

The problem is that there is almost no research regarding the efficiency of UV rays on a moving stream of air, so you have absolutely no idea what kind of wattage you need in order to be effective.

[Mark Gulbrandsen]

Totally agree Marcel, I have not been able to find any data at all on UV light treatment. Best to stick with MERV 12 filters if the air handler can do it.

[Carsten Kurz]

A colleague just bought a mobile air cleaner from a german company, Trotec TAC V+. It uses a HEPA 14 filter. This class is used for operating rooms in germany. In general, filters in these class ranges can never be operated solitary, but always need a pre-filter that prevents the H14 filter from clogging. The device my colleague bought uses a 'cheap' F7 (equals MERV 13) prefilter on the inlet that will be disposed off regularly. The HEPA H14 filter is metal and glass-fabric based and will sanitize itself regularly by electrical heating to around 100 °C within the device. These portable devices, however, are typically not suitable for larger auditoriums.

[Mark Gulbrandsen]

Carsten, Heppa 14 is the same as a MERV 14 filter here in the States. AMC is installing MERV 13 filters evrery where. Don't know if anyone else is or not. Apparently UV treatment is not an approved thing here in the States.

[Carsten Kurz]

No Mark, HEPA 14 is not the same as MERV 14. Not even close. More like F7/F8.
Conventional HVAC systems can not work with typical HEPA 14 filters due to airflow issues. MERV13/14 or F7/F8 are used as pre-filters/coarse filters for HEPA 14.

http://iaqtechnology.eu/files/File/T...filtersEng.pdf
https://static1.squarespace.com/stat...Chart+2016.pdf


- Carsten

[Mark Gulbrandsen]

Coirrect Cacrsten. Mer 8 is about as high as an HVAC can take. However, Merv 14 and Heppa 14 filters do exactly the same job of filtering out the same size particles. IDK what AMC did to modify their air handlers, but they obviously did something. to make MERV 13 work.

[Marcel Birgelen]

A colleague just bought a mobile air cleaner from a german company, Trotec TAC V+. It uses a HEPA 14 filter. This class is used for operating rooms in germany. In general, filters in these class ranges can never be operated solitary, but always need a pre-filter that prevents the H14 filter from clogging. The device my colleague bought uses a 'cheap' F7 (equals MERV 13) prefilter on the inlet that will be disposed off regularly. The HEPA H14 filter is metal and glass-fabric based and will sanitize itself regularly by electrical heating to around 100 °C within the device. These portable devices, however, are typically not suitable for larger auditoriums.

That's also something we discussed with local health authorities and they're not fond of mobile air-filtering solutions. Right now, they're working with schools in order to try to reopen them somewhat safely and it's especially older buildings that haven't been retrofitted with modern HVAC systems that face quite some challenges.

The reason why mobile solutions are seemingly discouraged is, because most mobile units are installed on ground level. They suck in air and push it out around that same level. This causes air circulation to go gravitate towards those machines, so a lot of air inside the room will start to circulate horizontally. This causes "used air" to potentially travel alongside other occupants in the room, therefore increasing risks of spread through the air instead of reducing it.

A traditional HVAC system removes air from the top of the room. Therefore, "used air" will largely move straight upwards. So, any aerosols containing virus particles will primarily move towards the air-vents that remove air from the room. The reduced amount of horizontal airflow in those rooms, should reduce the amount of virus spreading due to aerosols pretty effectively. If the circulated air is treated with an air-filter that's sufficiently fine to block most virus particles, your HVAC system should be mostly trouble free. Obviously, those filters require frequent maintenance and those filters should be considered bio-hazardous material.

Like Mark indicated, any UV based air-treatment systems aren't approved methods to "kill" the coronavirus, not in the EU and also not in the U.S. While around here, it's technically not illegal to install any such system, it's not a certified method and can't be advertised as such.

[Mike Blakesley]

If we're going to start worrying about HVAC systems now, along with aerosols (the new fact that the virus can float around in the air for a long time), the next thing will be that we're not even safe outside as long as any other people are within 20 or 25 feet of us. At that point we might just as well shut down everything, go into lockdown, stick our heads between our legs and kiss our asses goodbye.

Let's see.... we've been told that you can get it if you accidentally brush up against a surface that an infected person happened to touch in the last two days; but oh wait, now it's not thought to spread much from surfaces. We've been told to stay 6 feet apart, but now "aerosols" can float 20 feet or more, depending on whether the person is talking, yelling, singing, coughing or just breathing. We've been told that everyone needs to be tested and in fact we'll never know how we're doing until EVERYONE gets tested, but now the CDC is saying tests aren't that necessary for asymptomatic people.

We had the WHO saying don't wear masks. Then the government said, yes, please DO wear masks. If there's not enough masks than any face covering will do, but you have to have a wire to make it tight around your nose so I guess NO, not just any face covering will do. But anything is better than nothing, but make sure it doesn't have a politically-incorrect logo on it because that's bad.

We're told that churches, theaters, weddings, and "gathering over 50 people" are dangerous, but protests and mass gatherings in the name of a political cause are OK. And schools are dangerous, unless the kids all wear masks, but if they are playing a sport (with a communal ball being touched by everyone) then they're OK, but we can't allow parents to watch them. We're not allowed to see our elderly loved ones in nursing homes at all. We're told that you don't need to worry unless you are in close contact with somebody for over 15 minutes, but you also don't dare touch a door handle that hasn't been sanitized since that last person touched it.

It's enough to drive a person out of their fucking mind. At least, I know that's what's happening to me.

[Mark Gulbrandsen]

I know masks do work. I watched covid numbers go way down here in tje Nashville area once they were mandated. Areas that have big populations and no mandate are still battling the numbers.

[Steve Guttag]

Mike...there is a definite degree of frustration but you do have to allow that with a novel virus, there is going to be an ongoing learning with how to deal/live with it so one shouldn't hang on an earlier recommendation before new data would change the recommendation. On the mask thing, part of the issue was a shortage and there was a need to prioritize health care workers got the N95 masks, in particular and not every Nervous Nelly. There are things that continue to be true as data continues to come in...Older people have a MUCH harder time with the virus so yeah, you can't really go visit Grandma safely...even now unless you know, for sure, you are COVID free. My mother-in-law is a nurse and works at a retirement home and their rules are STRICT. All nurses are tested weekly (nasal swab) and temps measured daily. If you have ANY COVID symptoms, you need to test negative twice before you are allowed back in (and they do the testing outside...you don't even get in the building until you are tested safe! She tested positive recently. And, via contact tracing, that required everyone in our household to get the nasal swab testing too. That is how testing and contact tracing works...if you get a positive, you quickly see where it may have spread to or were it might have come from. As it turns out...we all tested negative...as did she! After testing negative 3 consecutive times, she was permitted back to work. Even the nasal swab can yield a false-positive 5% of the time. That is something about statistics people don't seem to understand That percent accuracy is just that and you will get incorrect results both ways. But, for the moment, it is the best we have.

We all have our personal experiences and our personal risk/benefit levels. I, personally, would have no fear of going to see a movie in a theatre with hard-tickets and distancing. I have no intention of getting on a plane, however. My odds of getting a cold or other illness is MUCH higher when I travel by plane and I have no desire to get this one. I've opted out of bowling this season because I just don't want the prolonged relatively close contact with people I just don't know. They are doing their best to keep people distant by cutting the lane count in half so teams can sit on every other lane but not everyone on a team lives in the same house so there are variables there. I'm not comfortable with that. The other things about league bowling is people are more finicky about their equipment. Many people will wipe the lane oil off of their ball at each throw...so...once wiped they drop their rack on the rack...perhaps on my ball. That rag, which was on their hand and wiping a ball that also was on their hand is now resting on my bowling ball. Furthermore, while on the rack, your ball can be touching 2 other balls of unknown status. Low risk? I'm sure. I already decided that if I bowled, the ball would come back with me to where I'm sitting (actually 2 balls since I have a "spare" ball as well as a strike ball at all times. In the end, I decided to forgo bowling this season.

The amount of hand washing, I do now is WAY WAY higher than before and how far I stand away from people is WAY higher...it is like we each have magnets of the same pole and as you get near me...I get further away. This spring/summer I was installing a new 10-plex. Fortunately, few people are in a projection booth so when I was up there...no mask. When other workers were up there, a light weight "typical" mask. If I was downstairs where all of the various trades were...N95 mask...that was my comfort level. In my car...i have a box of standard masks (the blue/white ones) and a pack of KN95s. Depending on where I'm going/doing is what I put on when I get out. When I pump gas or mail stuff or know I'm going to touch what others have touched...gloves. What I know is I have been around those that have tested positive (besides my mother in law) and I have come up negative and, honestly, haven't caught anything either...so, for now, that's my comfort level. I come back to...yeah, I'd watch a movie in a movie theatre now. I've seen no study that shows that movie theatres aren't as safe as any indoor business. There are doctors with speculations and assumptions but no proof-positive study done in movie theatres that show COVID-19 goes from one to another by way of HVAC. I could see spraying down the seat or something.

[Marcel Birgelen]

If we're going to start worrying about HVAC systems now, along with aerosols (the new fact that the virus can float around in the air for a long time), the next thing will be that we're not even safe outside as long as any other people are within 20 or 25 feet of us. At that point we might just as well shut down everything, go into lockdown, stick our heads between our legs and kiss our asses goodbye.

I guess part of the problem is that in the U.S., much more than in most other western countries, this whole thing has been completely politicized. Do yourself a favor and don't fall for that, you're way smarter than that. Like Steve and many others have indicated, this whole thing is a giant moving target, about 7 to 8 months ago, practically nobody had seen this thing and we had to go by very limited information. But still, look at the science, even when insights are changing and people have made wrong decisions based on previously faulty assumptions. Science is still the most reliable thing we have. Those who have ignored science have paid a pretty hefty price or are still on the hook for doing so.

The advice, in the beginning, not to wear masks was primarily to avoid exhaustion of those masks for those who really needed their masks to protect their dear lives. Those people working on the front-lines in the hospital. There was also not much known about the effectiveness of masks. In the beginning, there was also the somewhat false assumption that the virus primarily spreads via contact surfaces. While it does that to a smaller extend, it now seems that this isn't the primary vector of infection. What we know now is that it primarily spreads through the air and not via direct contact.

Prolonged exposure to UV light kills the virus pretty effectively, that's probably why chances of catching the virus while being outdoors and not necessarily in big groups, are absolutely minimal, especially with warmer temperatures. In such cases, a mask also does close to nothing, that's why even not wearing a mask while walking in a park and people are social distancing, nothing much will ever happen.

What we have seen though, unfortunately, time and time again, is that whenever people pack closely together and especially in either colder weather or indoor spaces, or in other words: places where people pack together and there is no or limited exposure to UV light, stuff tends to get problematic. If that indoor space is cold, stuff tends to get even worse. This is also where both masks and HVAC systems come into place.

The average non-medical/non-(K)N95 mask will not do much for yourself, but it will protect others around you. A mask will effectively reduce the amount of aerosols you put into your direct environment, so an infected person will also put less of the virus-containing aerosols in the same room.

Now, if you have a HVAC system which effectively filters the air with a sufficiently fine-meshed filter, you'll remove almost all of the remaining virus-containing aerosols from the air. So, if people are wearing masks, are social distancing and the HVAC system is equipped with a qualifying filter, with all the information we have now, we can say you've created a pretty safe indoor space, one that I will also gladly visit.

I guess by this point we're all frustrated about how stuff is progressing, but you really need to hang in there. Don't let yourself get misinformed by some politicians who only have one priority: being (re)elected, just look at the real data out there. We all knew this thing will take at least two years to ride out. Even if they have a definitive working vaccine tomorrow, it will be mid-2021 before it's available in quantities. The fact that many people in the U.S. have already indicated to opt-out of an eventual vaccine will probably prolong stuff even further...

While the media may celebrate lower death numbers, keep in mind that while the chances of dying from this are indeed falling, also due to the stuff we learned over the last months, this thing may come with pretty nasty long-term consequences, even if you're only suffered a relatively mild case of it. Also, if you catch it, you may unwittingly transmit it to people close to you, some people who may suffer dearly. Keep your heads up, try to ride it out, be creative, but stay safe... in the end, all the money in the world is worth nothing if you can't enjoy a good health...