Most of us are underestimating the importance of the Hepa Air Filtration System

[ModelX]

I am near SLC with an occasional long commute. Our air can get very bad! I will be happy to have clean air while driving!

 

[Aljohn]

The Air Filtration system is one of those things that wasn't "sexy" to explain. I found it a little boring during the Launch session in California. First, it seeemed a bit misplaced in the presentation. Everyone was awaiting the falcon doors and other "sexy" features while Elon went through the filtration system for what seemed like forever after waiting an hour and half to get into the presentation area.

In hind sight, the Filtration System has its purpose -- China! The documentary -- Chasing Extenction -- points out that 4,000 people a day die of respiratory desease (attributable to polution) in China. 4,000 a DAY -- how much would you pay for car cabin to drive or be driven. I won't speculate on all the other features of the Model X. But I have no doubt that Mr. Musk knows exactly what he is doing. We only have part of the puzzle.

 

[Discoducky]

After living in the bay area for 1.5 years and commuting from Fremont to Palo Alto everyday through Milpitas and afternoon over the Dumbarton Bridge I would use Bio mode everyday. My now 6 year old would say "oh no, not the stinky bridge!"

Model S could not filter out Milpitas nor the bridge smell so I'd get bio mode just for that if I still had that commute. Thankfully, the Pacific Northwest has much cleaner and less stinky air, but will still get it anyway just in case I end up doing that commute again in the future

 

[EarlyAdopter]

When the Model S cabin air filter didn't yet contain active carbon, I swapped it out for an after market filter with active carbon.
The difference was noticeable and for € 15,00 I considered it a bargain.

Which one? I'd like to do the same. If you could make a post on it over in the Model S section, you'd be very popular.

 

[PaulusdB]

I posted that information in the Dutch / Belgian section of TMC.
http://www.teslamotorsclub.com/show...tieve-koolstof?p=670428&viewfull=1#post670428

That specific filter was for Ford Ka and had to be trimmed to the right length.

Note the right dimensions for Tesla Model S: (l x w x h) 245 x 156 x 30

Nowadays Tesla Motors stocks an OEM cabin filter with active carbon for Model S.
So you can try to get one directly from them.

And nothing wrong with my popularity, thank you very much.
Working on my eleventh bar...

Which one? I'd like to do the same. If you could make a post on it over in the Model S section, you'd be very popular.

 

[mzpolo]

Y'all realize that if you spend 2 hours a day, you spend just under 6% of your day in the car? You also remember that the air INSIDE the car got there when you opened those really cool falcon wing doors?
Somewhere in this thread I hope someone has already pointed out that nearly every car built after about 2005 has a cabin air filter. OK, its not MOPP Level 4 (Google it), But it gets the crud that needs to be gotten.

No... "bio defense mode" is a cool feature, not a needed feature.

Yea... not the way to get rep points but lets be real folks. Its a car, a really really cool one... but its a car.

 

[ohmman]

Agree:
Valuable in China
Probably developed to appeal to Chinese market
Is OK to value it for your own reasons but not pretend that they're scientifically accurate
May reduce or eliminate occasional "stank"

Disagree:
Makes any difference anywhere else
Makes difference compared to standard filter with regard to pollen
Will make any difference in your health

 

[EarlyAdopter]

I posted that information in the Dutch / Belgian section of TMC.
http://www.teslamotorsclub.com/show...tieve-koolstof?p=670428&viewfull=1#post670428

That specific filter was for Ford Ka and had to be trimmed to the right length.

Note the right dimensions for Tesla Model S: (l x w x h) 245 x 156 x 30

Nowadays Tesla Motors stocks an OEM cabin filter with active carbon for Model S.
So you can try to get one directly from them.

And nothing wrong with my popularity, thank you very much.
Working on my eleventh bar...

Well, the stock one in the Model S doesn't cut it. Get behind a smelly truck or car and it still smells bad. I don't ever want to smell another ICE vehicle exhaust again. I'm confident this won't be a problem with the X.

 

[Jeva]

It maybe makes sense if you plan to be in the car for hours and hours and hours. The second you open the door or open the window, it's "dirty" air all over again until the car is closed and air filtered. I have about a 2 hour total commute daily. Even in the most polluted city, the air filtration is going to have a minuscule impact on mitigating ill effects from pollution. It's more or less a gimmick. Unless you intend to wear a respirator when out of the car, any health benefit is imaginary.

 

[deonb]

So how can something be 500x Better than something that's already close to 100% efficient?

The 500x is not on the "how many particles are being filtered" side, but the "how many particles are getting through" side.

So let's say one filter lets one bad particle in 100 through, and a second filter lets one bad particle in 50'000 through, the second one would be 500 times more efficient, even though the first one was already "99% efficient".

 

[ohmman]

The 500x is not on the "how many particles are being filtered" side, but the "how many particles are getting through" side.

So let's say one filter lets one bad particle in 100 through, and a second filter lets one bad particle in 50'000 through, the second one would be 500 times more efficient, even though the first one was already "99% efficient".

I still have trouble with this version of math. :wink:

If a filter is 99% efficient, and we agree that means it removes 99% of particulate matter, then a filter that is 99.998% efficient is one that lets one particle in 50k through.

The increase in efficiency would then be:

(0.99998 - 0.99) / (0.99) = 0.01008

It's 1.008% more efficient.

 

[jerry33]

I still have trouble with this version of math. :wink:

If a filter is 99% efficient, and we agree that means it removes 99% of particulate matter, then a filter that is 99.998% efficient is one that lets one particle in 50k through.

The increase in efficiency would then be:

(0.99998 - 0.99) / (0.99) = 0.01008

It's 1.008% more efficient.

I believe the missing piece is the size of the particles let through. The 99% refers to 99% of the size that the filter is designed for.

My concern is frequency and cost. Is it like IQAir where the frequency works out to about twice a year at $200 per filter (and some need multiple filters).

 

[Fallenone]

Compared to the 99% efficient one that lets 500 through, it is 500 times better.

Or think in (1-99%)/(1-99.998%) = 500

I still have trouble with this version of math. :wink:

If a filter is 99% efficient, and we agree that means it removes 99% of particulate matter, then a filter that is 99.998% efficient is one that lets one particle in 50k through.

The increase in efficiency would then be:

(0.99998 - 0.99) / (0.99) = 0.01008

It's 1.008% more efficient.

 

[ohmman]

Compared to the 99% efficient one that lets 500 through, it is 500 times better.

Or think in (1-99%)/(1-99.998%) = 500

No. This is still incorrect. Let me try explaining it in a more concrete way. Since a filter by nature is responsible for retaining particles, you count how much it filters.

Let's assume there are 100,000 particles in some volume of air, moving across both filters at the same flow rate.

Filter 1 (standard): 0.99 efficiency, filters 99,000 "particles".
Filter 2 (HEPA fance-o-calrissian): 0.99998 efficiency, filters 99,998 "particles".

Since efficiency is rated in retained particles:

(99998 - 99000) / 99000 = 0.1008.

That said, jerry33 nailed it. There's a difference, but to measure it with some "500x" metric is kind of ridiculous. All of our calculations make the assumption that "particles" are evenly distributed across size. That's a foolish notion. I don't pretend to know much about the distribution, but a search shows varied results (none of them flat).

HEPA filters are excellent air filters. In some environments, they're probably quite useful. I can say those things factually. But I think we should be careful throwing out numbers that have no scientific basis. It's misleading.

(Note, happy to be proven wrong if there is some better analysis).

Edited to add this interesting study: http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/6984/report/2004

 

[dhrivnak]

You must have no allergies or don't mind paying for your allergy medications.

You live in TN and don't see the value of not being exposed to Pollen?

I guess you can say I value fresh air most. My "commute" to work is 2 miles so most days I ride my bicycle. Then in my off time I am working in the yard, walking the dog or taking the scouts hiking/camping. All with no filters or allergy medicine. I do use Kleenex on occasion but it is very low cost.

 

[Canuck]

Driving in LA I can see why someone would want it. Also in China:

Bottles of fresh air from Canada are a hot sale in China as smog remains high | Daily Mail Online

But since I often drive through fresh Canadian mountain air, give me a vent that I can open rather than the filter in the car so I can keep the windows closed and still breath fresh air. It bothers me that there's no way to just get fresh air in the car without turning on the temperature control or opening the windows/roof which causes sound/vibrations.

 

[Fallenone]

The purpose of a filter is to prevent particles going through, unless you're using it to measure the amount of particles that passed a certain airflow over a certain duration of time. So measuring how much it filters or how much it let go are both correct. the 500x better is simply taking an angle that is psychologically more appealing to people, but nothing scientifically wrong with that. I would even say in this specific situation, where protecting the passenger's health is the goal, the 500x by measuring how many particles that got through is a bit more correct. How many particles retained by the filter has nothing to do with the passenger's health, how many get through does.

And you are totally correct particles have a wide range of distribution with different distribution patterns based on the sources. The most common one is a log-normal distribution. And our calculation is not based on assuming an even distribution of particle size. Although in reality it is much more complicated, but the essence of a filter is like a sieve, the finer its holes, the less particles get through (or more particles get retained if you prefer). So the reason why a filter can have 99% efficiency or 99.998% is because the later has smaller "holes" in it, therefore capturing more smaller particles and preventing them to get through. The mechanisms of creating and restricting the size of those "holes" can either be having multiple layers of fibers to create layers of "nets" upon each other, or having adsorbents such as active carbon. Of courser there are other ways to build a filter. If we assume the size distribution is log-normal, we can also realize how difficult it would be to have greater efficiency after we pass the peak of the size distribution.

No. This is still incorrect. Let me try explaining it in a more concrete way. Since a filter by nature is responsible for retaining particles, you count how much it filters.

Let's assume there are 100,000 particles in some volume of air, moving across both filters at the same flow rate.

Filter 1 (standard): 0.99 efficiency, filters 99,000 "particles".
Filter 2 (HEPA fance-o-calrissian): 0.99998 efficiency, filters 99,998 "particles".

Since efficiency is rated in retained particles:

(99998 - 99000) / 99000 = 0.1008.

That said, jerry33 nailed it. There's a difference, but to measure it with some "500x" metric is kind of ridiculous. All of our calculations make the assumption that "particles" are evenly distributed across size. That's a foolish notion. I don't pretend to know much about the distribution, but a search shows varied results (none of them flat).

HEPA filters are excellent air filters. In some environments, they're probably quite useful. I can say those things factually. But I think we should be careful throwing out numbers that have no scientific basis. It's misleading.

(Note, happy to be proven wrong if there is some better analysis).

Edited to add this interesting study: http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/6984/report/2004

 

[kptesl]

It's the same way with sunscreen. Going from SPF 15 to 30 offers 2x the protection. You go from blocking ~93% (with SPF 15) to ~96.5% (with SPF 30) of photons in the UV range. The protection factor doubles from 15 to 30, because you let through only half the amount of damaging photons (3.5% vs. 7%).

The purpose of a filter is to prevent particles going through, unless you're using it to measure the amount of particles that passed a certain airflow over a certain duration of time. So measuring how much it filters or how much it let go are both correct. the 500x better is simply taking an angle that is psychologically more appealing to people, but nothing scientifically wrong with that. I would even say in this specific situation, where protecting the passenger's health is the goal, the 500x by measuring how many particles that got through is a bit more correct. How many particles retained by the filter has nothing to do with the passenger's health, how many get through does.

And you are totally correct particles have a wide range of distribution with different distribution patterns based on the sources. The most common one is a log-normal distribution. And our calculation is not based on assuming an even distribution of particle size. Although in reality it is much more complicated, but the essence of a filter is like a sieve, the finer its holes, the less particles get through (or more particles get retained if you prefer). So the reason why a filter can have 99% efficiency or 99.998% is because the later has smaller "holes" in it, therefore capturing more smaller particles and preventing them to get through. The mechanisms of creating and restricting the size of those "holes" can either be having multiple layers of fibers to create layers of "nets" upon each other, or having adsorbents such as active carbon. Of courser there are other ways to build a filter. If we assume the size distribution is log-normal, we can also realize how difficult it would be to have greater efficiency after we pass the peak of the size distribution.

 

[ohmman]

I would even say in this specific situation, where protecting the passenger's health is the goal, the 500x by measuring how many particles that got through is a bit more correct. How many particles retained by the filter has nothing to do with the passenger's health, how many get through does.

Yep. I realized after posting last night that my approach was incorrect, but figured since I asked to be proven wrong.. I'd let someone do it. :smile:

And you are totally correct particles have a wide range of distribution with different distribution patterns based on the sources. The most common one is a log-normal distribution. And our calculation is not based on assuming an even distribution of particle size. Although in reality it is much more complicated, but the essence of a filter is like a sieve, the finer its holes, the less particles get through (or more particles get retained if you prefer). So the reason why a filter can have 99% efficiency or 99.998% is because the later has smaller "holes" in it, therefore capturing more smaller particles and preventing them to get through. The mechanisms of creating and restricting the size of those "holes" can either be having multiple layers of fibers to create layers of "nets" upon each other, or having adsorbents such as active carbon. Of courser there are other ways to build a filter. If we assume the size distribution is log-normal, we can also realize how difficult it would be to have greater efficiency after we pass the peak of the size distribution.

Right. And if the size distribution peaks well before whatever the 99% filter is capturing, it's possible that while the 99.998% filter would in theory let fewer through, it's really not capturing much more. Or, vice versa, if the peak is in the sweet spot of the 99.998% filter, then it would be vastly superior.

Actually, thanks to this thread, I've done more reading on filtration than I ever thought I would. That link I posted discusses how the distribution of ultra fines drops off rapidly due to coagulation and coalescence, which I also found pretty interesting.

 

[MitchJi]

Air on the road != air in the car. Air on the road is much worse than air in the car. The HEPA on MX only affects air in the car, has nothing to offer to anywhere else people are.

Regarding to the excerpt on children health, do you see anything there has anything to do with air quality in the car? I cannot stress enough the differences between air quality's impact to human health and air quality in the car to human health.

Speaking as a phd in Environmental Health Sciences specialized in air pollution related health risks, I can assure you the air quality in cars is at the bottom of the list of concerns when you are worrying about air pollution, unless for those professional drivers.

According to the authors of these studies you are incorrect. Air quality inside cars is much worse, and the authors believe it is a serious problem.:
Why you could suffer from more pollution while driving a car than walking on the streetÂ* | Daily Mail Online

Why you could suffer from more pollution while driving a car than walking on the street

People in cars exposed to up to 15 times pollution of walkers and cyclists
Emissions are highest in the centre of the carriageway, where the cars are
Dirty air is sucked in through car air filters and breathed in by passengers
Study run by Environmental Audit Committee - cross-party group of five MPs
MPs inhaled average of 50 million soot particles per breath in London cab
Those who live in big cities have lower life expectancies because of pollution

Passengers in cars and taxis are being exposed to air pollution up to 15 times greater than cyclists and pedestrians on busy city streets, a new study has found.

Travelling inside a vehicle could be much worse than cycling by the kerb or walking on the pavement because emissions are highest in the centre of the carriageway, where vehicles suck in dirty air from those in front, scientists say.

Their shocking findings were revealed following an experiment by a group of five MPs who sit on the Government’s cross-party Environmental Audit Committee (EAC).

Each was provided with a gadget to measure airborne pollution levels, as well as a GPS tracker device, by scientists from King’s College London, who analysed where pollution was at its highest during their travels across London and in their constituencies over a week in July.

By far the highest levels of tiny particles of ‘black carbon’ or deadly soot breathed in by the MPs was during taxi journeys in cities.

On average each inhaled around 50 million particles per breath while inside a cab in London, around seven times more than the six to seven million particles per breath inhaled while walking around Whitehall or Oxford Street, and 15 times greater than levels recorded outside their eventual destination City Hall where, on leaving the cab, levels fell to three million particles per breath.

The findings are worrying because persistent inhalation of air pollution and traffic emissions have been linked to lower life expectancy and serious illnesses, including heart disease and cancer, as well as low birth weights and stunted lung development in children.

Ben Barratt, a lecturer and air quality scientist at King’s College, said that air pollutants, such as black carbon, nitrogen dioxide and the toxic leftovers of inefficiently burnt fuel, were highest in the middle of a carriageway and in the first two to three feet above the road, dropping off nearer to the kerb and pavement.

‘Travelling in vehicles gave the greatest average exposure,’ Dr Barratt said.

Five MPs carried out the Environmental Audit Committee study in London taxis

‘When you are in a vehicle, nose to tail with those in front, you are right in the middle of the source of the pollution. ‘Vehicles close together suck in each other’s emissions.

‘The air intakes are in the engine compartment close to road level, so they pick up the fumes emitted by the vehicle in front of them. Open windows are another route.’

Dr Barratt said often dirty air became trapped in cars and taxis, whereas cyclists and pedestrians had a constant ‘flow of air’ breezing in from all directions around them.

Mr Johnson is expected to announce an new initiative – Breathe Better Together – where commuters will be asked to work from home or use bikes, trains and buses instead of cars and taxis when air pollution levels are highest.

However, it is not just in London where pollution is a problem. Mrs Walley’s monitor saw her inhale more than 80 million particles per breath during a car journey in her Stoke-on-Trent North constituency, while Mr Kane was exposed to 20 million particles per breath during a cab ride in Manchester.

Mrs Walley said: ‘Our monitoring equipment showed that people in vehicles were far more exposed to air pollution than they would be walking.

‘Car makers test exhaust emissions but this raises a question about whether they should also be considering air quality inside vehicles.’

Research suggests that up to 29,000 premature deaths are caused each year in Britain by pollution - 10 times the number of people killed in road accidents.

The biggest concern is the tiny bits of carbon - around 30 times smaller than a human hair - which are so small they can get into the lungs and even enter the bloodstream, passing through major organs, such as the heart and brain.

They can have immediate effects on people with existing health conditions, triggering asthma attacks, heart attacks and strokes.

Immediate effects.

Some images below from this pdf:
http://www.pureti.com/content/documents/ICTA-In-Car-Air-Pollution-Report.pdf

Since I can't put it in bold I'll call everyone's attention to the last paragraph above.

And the section starting with "Similarly"..."elevated levels of auto exhaust" above.