HEPA filters don't work for smoke

[THAIJAMES]

According to the particle size on Wikipedia smoke particles are smaller than .3 microns and can't be filtered by standard HEPA filters what do you think?

https://en.m.wikipedia.org/wiki/Particulates

 

http://csceng.com/services/indoor_air_quality/after_the_wildfire_smoke_has_cleared/index.php

[impulse]

I'd have more confidence in a graph without so many spelling errors. 

 

If they don't get the spelling right, what else are they getting wrong?

[THAIJAMES]

1 hour ago, impulse said:

I'd have more confidence in a graph without so many spelling errors. 

 

If they don't get the spelling right, what else are they getting wrong?

I don't see any spelling mistakes in the graph.

 

the original article from Wikipedia is very good and has excellent formation about particle pollution.

https://en.m.wikipedia.org/wiki/Particulates

For example:

Particulate matter studies in Bangkok Thailand from 2008 indicated a 1.9% increased risk of dying from cardiovascular disease, and 1.0% risk of all disease for every 10 micrograms per cubic meter. Levels averaged 65 in 1996, 68 in 2002, and 52 in 2004

 

That means just the average of 65 micrograms you have a 12% increase from dying from cardiovascular disease.

 

The air is likely much worse in Chiang Mai

And the point is the HEPA filters we are using may not filter the smoke which is one of the the main causes of pollution up north.

 

You would need a filter that could filter down to  .01 microns HEPA filters only filter down to .3 microns

[vivid]

Regarding consumer grade stuff that you get in the market (eg Samsung, Sharp etc) ......

 

Other than 2.5, 1, 0.5 and 0.3 microns, their 0.1 micron performance is decent too.  There is still sufficient CADR for 0.1 microns.   

 

Share a reference video.  Just for reference coz at least they bothered to measure 0.1 microns UFP which is pretty expensive), i know it's more of a Dyson promotional video.

Source : https://www.youtube.com/watch?v=dFbSpp_q9WU

 

The rectangular pleated filter below is from a Sharp D40 (jap version or something).  Filtration is at about 87% at 0.1 microns for the H13 filter.

 

 

 

[vivid]

1 hour ago, THAIJAMES said:

 

You would need a filter that could filter down to  .01 microns HEPA filters only filter down to .3 microns

Haze caused by biomass burning has a particulate matter spatial distribution down to about 0.1 microns only.

 

eg

Distributions can be unimodal (see above) or multimodal (typically bimodal) as shown in the sketch below of cumulative volume versus particle size (from S. K. Friedlander, Smoke, Dust and Haze 2000).

 

And HEPA filters do handle that pretty ok.  HEPA H13, H12, H11 filters just do not "stop" at 0.3 microns.  0.3 microns is chosen just as a standard for filtration testing (eg DOP testing).

 

 

 

 

You might be reading and referring to traffic fumes particulate matter pollution, ie Ultra Fine Particles.  They do have some stuff in 0.1 microns and below.  Some smog types also have UFPs, those are the photochemical smog types that you get in some cities and not the current haze.

For eg, below shows traffic exhausted related particulate matter

 

 

Tobacco smoke average about 0.1 microns by count, 0.38 microns by mass.  So consumer HEPA does ok.

https://www.ncbi.nlm.nih.gov/pubmed/2751166

 The size distribution parameters obtained were similar for all cigarettes tested, with an average CMD (count median diameter) of 0.1 micron, a MMD (mass median diameter) of 0.38 micron, and a GSD (geometric standard deviation) of 2.0. 

[vivid]

If you ARE worried about traffic exhaust UFPs, you can spec U15-U16 grade ULPA filters and also commercial boxes of FFU-Fan Filter units meant for cleanrooms in manufacturing/pharma/labs, which are tested to be able to do 0.12 microns at an extremely high efficiency of 99.9995% (many times higher than HEPA 99.97%).  Note, that does not mean that they only filter 0.12 microns stuff and drop like a cliff.  HEPA are tested at 0.3 microns and maxes out at H14 grade. 

 

 

ULPA are quite expensive though.  The cheapest that you can get is from Taobao....and if anyone does not believe in China stuff, then good luck and i hope you have real deep wallets.

Consumer adapted versions, IQAir does use something that filters 0.003 microns at a very high efficiency (and also smaller than that at a good efficiency)of 99.5%, if i remember correctly Amway Atmosphere too, but way too bloody expensive for the relatively low CADRs you are getting .....you really are better off getting cleanroom FFUs.  Bloody expensive units, bloody expensive replacement filters. 

 

PS. Forgot about this.  IQAir 150/250 etc and Amway Atmosphere air purifiers do filter down way below 0.1 microns into the UFP territory and at a very high efficiency %, but only in their low fan speed modes, ie at low air velocity flowing across the ULPA media.  I believe Amway Atmosphere mentions this before.   You can use brute force power and force air past it and get higher m3/hr airflow, but the CADR for UFPs (< 0.1 microns) drops, though the CADR for 0.3 microns to 2.5 microns would go up.

A cleanroom FFU has a filter box that is a few times larger/more voluminous than the consumer air purifiers, they can support higher CADR for UFPs.   

So if you use IQAir/Amway for UFPs in a heavily polluted traffic place, practically you'd need probably need 2 units per room esp if it's a big one, if it is to be of any practical usefulness in terms of CADR sizing for the room coz you cannot make the room to be too airtight due to CO2 concentration buildup concerns.    

[vivid]

Too long didn't read version - don't worry, HEPA filters do work for the current dense haze in N Thailand caused by biomass burning. 

[impulse]

2 hours ago, THAIJAMES said:

I don't see any spelling mistakes in the graph.

 

How do you spell tobacco and allergens?

 

[impulse]

36 minutes ago, vivid said:

ULPA are quite expensive though.  The cheapest that you can get is from Taobao....and if anyone does not believe in China stuff, then good luck and i hope you have real deep wallets.

 

My big concern is that it won't stay clear very long if you're filtering down to those levels.  And the replacement filter elements are a huge part of the total cost.  In that past, even with HEPA filters, I always put a pre-filter on them to grab the bigger particles, and yet the HEPA filters would still plug up in a matter of days. 

 

Or was I doing something wrong?

 

[vivid]

3 hours ago, impulse said:

 

My big concern is that it won't stay clear very long if you're filtering down to those levels.  And the replacement filter elements are a huge part of the total cost.  In that past, even with HEPA filters, I always put a pre-filter on them to grab the bigger particles, and yet the HEPA filters would still plug up in a matter of days. 

 

Or was I doing something wrong?

 

 

Yes, you are right.   Of course, these expensive ULPA stuff are supposed to work in pretty pristine conditions.  A mesh prefilter at the intakes of the FFU does nothing in the the traffic conditions of BKK, much less Chiang Mai. 

So you might actually need to DIY another box and ducting and do a cheaper F9-H11 grade before the intakes of the U15-U17.

 

If you are talking about haze esp current very heavy haze levels, the concentration levels are even higher. That is why i mentioned a couple of times in other threads that instead of using $50-100 H13 original branded filters, go the "China way", they do cheaper H12 filters and they work just as well. Even cheaper still are those DIY type H11 panels without side sealing, bare naked pleated H11 media (something like those SmartAir cannon DIY types), in reality they measure to around 91-92% efficiency from my own testing.  Just $5 a pop, i'll take 10 @ AQI 800 levels, thank you!  ????

The chinese have already done the sums and found that their N China environment and requirements is really very different from other countries.  The recommendation is actually to change out every 45 days during their winter smoggy season, in fact 20-30 days or even less if you can afford it.   ????

 

It's a little more complicated than this, but just to show it more clearly in real life with regards to CADR.  

92% x 300 m3/hr = 276 m3/hr

99.9% x 300 m3/hr = 299.7 m3/hr

Heck H10's 85%  x 300 = 255 m3/hr

 

Other than plugging in a matter of weeks (or days as you reported, though i really think they can be used for a fair bit more in reality). another thing is that they do start to smell a bit.  How much it smells really depends on what is being burnt and differs from location to location or even country to country.   So during relatively clean days, you really start to smell the filter after a while, even though there is ample capacity left in the filter theorectically.   You gotta dispose of it, nobody wants a smelly filter.  

 

 

Put it in layman's term, you wanna use an inexpensive broom to sweep the streets or an expensive dyson vacuum cleaner? 

 

I've seen people saying that of course for such hazardous levels they'd want the best of the best to filter, but is it really practical in the first place.  And even then, can people really afford running multiple units at such high levels and especially over extended duration?  Those expensive filters are not gonna last and keep at that high airflow level, esp if the house is leaky. 

 

[vivid]

An IQAir set is even more expensive than those branded $50-100 H13 filters (I was paying something like $100 for the Sharp filters here in Singapore).   IIRC, for IQAir it is close to $1k here.   Imagine running 3-4 units of those around the house.  ????   Blueair ain't cheap too.

Just not very practical, right? 

 

PS. Talking about ULPAs and cleanrooms, here in Singapore 2015, the dense haze did cause some issues to wafer productions even though they have ample prefiltering.   So yeah, tough conditions.   Can't seem to be able to google those articles though, but you get the idea.

 

[THAIJAMES]

4 hours ago, vivid said:

Too long didn't read version - don't worry, HEPA filters do work for the current dense haze in N Thailand caused by biomass burning. 

Wow thank you for your very informative and expert type opinion. I'm still trying to digest it all and no doubt we'll have more questions.

 

I started this thread because I thought that my girlfriend was foolish for buying an Amway filter and thought that a regular HEPA filter should be good enough.

 

Using its state of the art Inteliflow technology, the Atmosphere Sky™ unit’s HEPA-based filter** effectively removes 99.99% of particles as small as .007 microns as they pass through the filter. It is fast, quiet and effective – all while maintaining high energy efficiency with low power consumption. The Clean Air Delivery Rate (CADR) is no less than 300 at speed 5 – perfect for cleaning the air in rooms up to 43.5 m2 (465 sq.ft.) in size.

 

As it turns out I may be the foolish one for relying on my p.m. 2.5 sensors and regular HEPA filters.

[THAIJAMES]

5 hours ago, vivid said:

 

The rectangular pleated filter below is from a Sharp D40 (jap version or something).  Filtration is at about 87% at 0.1 microns for the H13 filter.

So basically what you're saying is that it may not get all of it at the first pass but after a few passes it will get most of it eventually?

[vivid]

2 minutes ago, THAIJAMES said:

So basically what you're saying is that it may not get all of it at the first pass but after a few passes it will get most of it eventually?

 

Yes, that is correct.  99.99999%, 97%, 92%, 87%.....all will work, just a matter of time difference.

 

Don't worry about the UFPs, unless if you are living right beside a what.....super 5 lane x 2 directions expressway that is constantly clogged and the diesel vehicles are not even Euro 1 and cars don't have cat convertors, then yeah i'd get the Amway Atmosphere or IQAir 250, or DIY my own cleanroon FFU.  

 

Chiang Mai......umm....well i think the traffic is still not too bad right?  Original consumer branded filters would still work great, a Xiaomi would still work great, maybe those China $5 H11 filters are a wee bit lacking but hey they are cheap and so you can operate multiple units to make up for it.   A xiaomi replacement filter runs about $25?  So do you own sums for the long term.  ????

 

  Now, if you are in Chittagong Bangladesh, or some city in India, heck even New Delhi is hardcore, i'd use the Amway Atmosphere/IQAir 250, no doubt about it.   Even N China is seeing quite a bit of changes.

 

Another thing that they mention is that for really super small UFPs way smaller than 0.1 microns, even with a very high particle count, their total mass concentration (ug/m3) is so small due to them being so light that the overall danger is not high.  Even though, yes, they do get past the lungs as if the membranes there is like nothing.

[vivid]

BTW, those cheap China laser particle counters are usually using Plantower brand laser particle modules, cheap but still sensitive to around 0.5 microns and have usable sensitivity to 0.3-0.2 microns.  

This is the module......am sure if you open up the meter and see, you'd see this module.  Some meters come in acrylic plastic, semi DIY style, you already can see that clearly.  There are several version over the years, G1, G3, G5 etc...

https://s.taobao.com/search?q=plantower&type=p&tmhkh5=&spm=a21wu.241046-cn.a2227oh.d100&from=sea_1_searchbutton&catId=100

 

 

 

Nowadays i think most are already using the laser particle modules, a few years ago they were still using some Sharp brand IR module, the same module is used in the Sharp air purifiers.  The same laser modules are used in Xiaomi APs, china APs etc.  Not all, but those branded ones would be using laser.

 

You can check your own PM2.5 meter with cigarette smoke, that gives you a good predominantly ~ 0.3 microns source, and very little of the big stuff.  If you want am evem smaller particulate matter source, unfortunately i don't know of any.  heh...

[vivid]

For the Amway Atmosphere Sky AP that your GF has just bought, well, just use it in good health.

 

A good way to ensure filter longevity is to have another 1 or 2 Xiaomi in the same room/house.  That way the Amway is not doing all the heavy lifting.  Else i can already hear your GF's wallet screaming for current N Thailand conditions.   ????

 

If it's to guard against vehiclular pollution in CM during May - Jan, those levels are probably fine, use it in good health.

 

BTW, don't forget, only set the Amway Atmosphere Sky in fan speed 1 or 2 (the lowest ones), for best UFP filtration. 

I think they do write it somewhere in the manual or something as well, i have come across that.  

Else you gun 400 m3/hr across the media, it would not filter UFPs.  Slowly is the word.

If you want to filter haze, pollen, cigarette smoke, no issue, gun it hard.

 

The air purifier hardware is just a box and a fan.  The pleated filter is doing all the real work.   For UFPs, the filtration is done by a process  called xxxxx is it called diffusion? (check it out in a while) in which needs low airflow speeds across the filtration media.  There are like a total of 4 processes that work in HEPA filtration.

 

 

 

 

Oh yes....it's called Diffusion.  3 processes at work here.

 

Diffusion

an enhancing mechanism that is a result of the collision with gas molecules by the smallest particles, especially those below 0.1 µm in diameter, which are thereby impeded and delayed in their path through the filter; this behavior is similar to Brownian motion and raises the probability that a particle will be stopped by either interception or impaction; this mechanism becomes dominant at lower air flow velocities.

Interception

where particles following a line of flow in the air stream come within one radius of a fiber and adhere to it.

Impaction

where larger particles are unable to avoid fibers by following the curving contours of the air stream and are forced to embed in one of them directly; this effect increases with diminishing fiber separation and higher air flow velocity.

Diffusion predominates below the 0.1 μm diameter particle size, whilst impaction and interception predominate above 0.4 μm.^[7] 

 

In between, near the most penetrating particle size (MPPS) 0.21 μm, both diffusion and interception are comparatively inefficient.^[8] Because this is the weakest point in the filter's performance, the HEPA specifications use the retention of particles near this size (0.3 μm) to classify the filter.^[7] However it is possible for particles smaller than the MPPS to not have filtering efficiency greater than that of the MPPS. This is due to the fact that these particles can act as nucleation sites for mostly condensation and form particles near the MPPS.^[8]

[THAIJAMES]

12 minutes ago, vivid said:

A good way to ensure filter longevity is to have another 1 or 2 Xiaomi in the same room/house.  That way the Amway is not doing all the heavy lifting.  Else i can already hear your GF's wallet screaming for current N Thailand conditions.   ????

 

If it's to guard against vehiclular pollution in CM during May - Jan, those levels are probably fine, use it in good health.

 

BTW, don't forget, only set the Amway Atmosphere Sky in fan speed 1 or 2 (the lowest ones), for best UFP filtration. 

I think they do write it somewhere in the manual or something as well, i have come across that.  

Else you gun 400 m3/hr across the media, it would not filter UFPs.  Slowly is the word.

Great advice!

So ideal for her would be to leave the xiaomi on while she's at work and then turn on the Amway when she's home.

 

She also bought the coway for her office.

That one can filter down to .1 micron

[vivid]

4 minutes ago, THAIJAMES said:

Great advice!

So ideal for her would be to leave the xiaomi on while she's at work and then turn on the Amway when she's home.

 

She also bought the coway for her office.

That one can filter down to .1 micron

 

Yes, i believe all those branded stuff, Coway, Philips, Sharp, Samsung, LG, even Xiaomi, Mfresh, Midea can do 0.1 microns pretty ok....no worries.

I actually have seen a picture of a Samsung being tested at 0.1 microns and the results, can't really seem to find it though.

 

No, just operate the Xiaomi simultaneously as the Amway.  ????  Actually if you can even find a way to duct most of the output of the Xiaomi to the Amway, even better, lay the Xiaomi on its side and blow at the Amway's intakes or something.   Won't look too good though i guess.

[Kelsall]

IQAir 250.  I leave it on 24/7 during this time of year.

 

 

[THAIJAMES]

3 minutes ago, vivid said:

No, just operate the Xiaomi simultaneously as the Amway.  ???? 

Is that because you think the leakage into the room would be great enough that it wouldn't make a difference to have the room pre-filtered with a cheap xiaomi s2

[THAIJAMES]

1 minute ago, Kelsall said:

IQAir 250.  I leave it on 24/7 during this time of year.

 

 

Were you be able to buy that in Thailand?

If so what was the cost.

[Kelsall]

3 minutes ago, THAIJAMES said:

Were you be able to buy that in Thailand?

If so what was the cost.

Yes, 59,000 THB.  the IQAir Facebook page is where I bought it.

[vivid]

8 minutes ago, THAIJAMES said:

Is that because you think the leakage into the room would be great enough that it wouldn't make a difference to have the room pre-filtered with a cheap xiaomi s2

Yes that is a fair point also.   Another reason is just to share the load between the 2, i mean the Amway filter is expensive.   Vehicular traffic fumes is probably what the Amway Astmosphere sky would excel in on fan speed 1 and 2, and burning season or no burning season smokey haze, there are still vehicles around.....  though arguably like i said the UFP components do not have a very high total mass concentration.   Traffic fumes also have 0.1 to nearly 1 microns of course (check the graph that i posted), which of course for those can be handled by the Xiaomi or whatever branded AP or even cheap DIY HEPA effectively and efficiently.  

 

But with that said, i think the CM traffic situation is not yet disastrous, even though it might be pretty bad at times.  But if your house is near a cluster of thai car or boat tuning workshops doing dynos many hours in a day or what, then power to the IQAir or Amway.  ????

 

Having cheap/brute force but still relatively effective stuff is always good.  another eg A massive wave of $5000 war drones armed with bombs.

[THAIJAMES]

11 minutes ago, vivid said:

Yes that is a fair point also.   Another reason is just to share the load between the 2, i mean the Amway filter is expensive.   Vehicular traffic fumes is probably what the Amway Astmosphere sky would excel in on fan speed 1 and 2, and burning season or no burning season smokey haze, there are still vehicles around.....  though arguably like i said the UFP components do not have a very high total mass concentration.   Traffic fumes also have 0.1 to nearly 1 microns of course (check the graph that i posted), which of course for those can be handled by the Xiaomi or whatever branded AP or even cheap DIY HEPA effectively and efficiently.  

 

But with that said, i think the CM traffic situation is not yet disastrous, even though it might be pretty bad at times.  But if your house is near a cluster of thai car or boat tuning workshops doing dynos many hours in a day or what, then power to the IQAir or Amway.  ????

 

Having cheap/brute force but still relatively effective stuff is always good.  another eg A massive wave of $5000 war drones armed with bombs.

I personally live near the hills so I'm not affected by the road traffic. She lives in town and is more likely to be affected by road pollution.

 

So a good conclusion for people living in Chiang Mai is if you're not very close to road traffic then the regular HEPA filter will be fine, but give it more time to work properly.

If you're in a heavily polluted part of the city and close to road traffic then spend the money and get a good filter you cannot put a cost on your health.

[vivid]

15 minutes ago, THAIJAMES said:

I personally live near the hills so I'm not affected by the road traffic. She lives in town and is more likely to be affected by road pollution.

 

So a good conclusion for people living in Chiang Mai is if you're not very close to road traffic then the regular HEPA filter will be fine, but give it more time to work properly.

If you're in a heavily polluted part of the city and close to road traffic then spend the money and get a good filter you cannot put a cost on your health.

Yep you can say that.

 

If you can well afford it and wanna get that last small portion of the overall big picture, and you are someone who likes being healthy, then go for it.   I'd also guess generally (not all of course) for people who are over 40-50 / have kids, they tend to pay more attention to health.    

 

Else the cheaper stuff also work great.  In fact the AP scene has improved by a lot, the China stuff are also pushing the boundaries not technologically but  brute force airflow at low costs.   Just ~ 10 years ago, the offerings were very limited, and very expensive.  I remember my Sharp 840 with just what...218 m3/hr costing nearly 400 dollars then.  Replacement filters, like i said, cost about $100.  

 

A Xiaomi 2S costs just usd 110 here in Singapore via local online sites.  A replacement filter like $25. Literally everyone has access to it. even the low income. That's good.  

And you can even control it via the internet, switching in ON when you are on the way back so that the home is purified when you open the door.     While a Daikin wifi module to plug into the aircon FCU is an additional $400 option here if you wanna switch on the AC via in the internet, which is bulls*** pricing.

[THAIJAMES]

10 minutes ago, vivid said:

A Xiaomi 2S costs just usd 110 here in Singapore via local online sites.  A replacement filter like $25. Literally everyone has access to it. even the low income. That's good. 

Wow. As usual the price is double in Thailand.

But to be honest with you even at 200 it's cheap.

I love being able to turn them on remotely an hour or two before I get home.

[donim]

What about using air ionizer ?

The smaller (ion) particles would stop floating around and drop on the floor, ready for a wipe.

Use this together with the hepa filter machines.

 

Any  - thought/experience/real measured situation -  on that?

[THAIJAMES]

The Dyson video that vivid linked to mentions that they lose efficiency after a few months.

 

[vivid]

3 hours ago, donim said:

What about using air ionizer ?

The smaller (ion) particles would stop floating around and drop on the floor, ready for a wipe.

Use this together with the hepa filter machines.

 

Any  - thought/experience/real measured situation -  on that?

Most models do not emit ozone but some might.   The cleaning effect is pretty small compared to the filter.

 

Just stick with HEPA and the airflow (CADR), then take note on the noise levels in medium, medium high, high speed, Turbo.  Replacement filter costs and availability.  Size and footprint of the machine. If possible, oversize the machine or aim to get multiple sets.  See which one gives you the best bang for the buck.  Generally won't go wrong.

[vivid]

5 hours ago, THAIJAMES said:

Wow. As usual the price is double in Thailand.

But to be honest with you even at 200 it's cheap.

I love being able to turn them on remotely an hour or two before I get home.

Dang it, S$139 only now at my local online site.  ????  

Tempted.

That's 3258B.  ????

Get 4pcs of them and your wallet won't even break a sweat, and then haul some 1200m3/hr of air.  Might need earplugs for continuous operation though.  ????