Photochemical smog and HEPA filter effectiveness

[hiroshiy]

Today in central wards (something like counties) in Tokyo issued warnings for photochemical smog. It is usually harmless but could be bad for health of young children and elderly people. Is HEPA filter and thus bio weapon defense mode effective on this type of pollution? My guess is that if the pollutant is particle then HEPA filter works, and if the pollutant is gas then it doesn't. Not sure what kind of pollution "photochemical smog" is and if they are particles how small they are. Any insights?

 

[Tam]

..."photochemical smog"...

I am no expert but let me guess: If you can visualize it, then it is pretty big in the world Tesla medical grade filter system.

Tesla claims its system can filter out bacteria, virus and even smells such as from cow manure at Harris Ranch Supercharger in California.

The smelly part (manure, rotten eggs...) of the air that you cannot see is methane CH4.

So here are their sizes from biggest to smallest:

Police Tear Gas against Anti-Trump crowd: 60 micrometers or 60,000 nanometers

Bacteria: 5.0 micrometers or 5,000 nanometers

Virus: 0.4 micrometers or 400 nanometers

Methane CH4= 0.000414 micrometers 0.414 nanometers

 

[Snowstorm]

Methane, CH4 doesn't actually have any smell. It is like natural gas. The rotten egg small associated with rotten eggs has to do with other sulfur compounds, which is often added to natural gas to alert us of leaks. I am pretty sure (though not 100%) that The Tesla filter cannot filter out these molecules as they are way to small. However, they may filter out particles of actual poo that can be suspended in the air which will emit those molecule, so the smell can be reduced.

 

[croman]

Most HEPA filters stop at viruses. You'd need a specialized filter for anything smaller.

 

[gearchruncher]

ALL Model X have activated carbon filters for smells.

The HEPA filter is for particles, and is always in the air loop as long as you aren't in recirculate. You don't need to turn bio weapon on.

 

[Tam]

Methane, CH4 doesn't actually have any smell. It is like natural gas. The rotten egg small associated with rotten eggs has to do with other sulfur compounds, which is often added to natural gas to alert us of leaks...

Thanks for the correction. My bad for not paying attention in chemistry class a long time ago

 

[hiroshiy]

Most HEPA filters stop at viruses. You'd need a specialized filter for anything smaller.

Thanks for the reply. Yes, I think HEPA filters can catch particles as small as 0.3 microns, but how about photochemical smog??

 

[gearchruncher]

According to wikipedia:

Photochemical smog is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds in the atmosphere, which leaves airborne particles and ground-level ozone.[16]

So no, a HEPA filter will not help as all that is at ground level is Ozone which is not a particle and will go right through a mechanical filter.

 

[Tam]

..So no...

The EPA defines air pollution by PM (Particulate Matter) sizes:

• PM10 : inhalable particles, with diameters that are generally 10 micrometers and smaller; and
• PM2.5 : fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.

Good air quality index is 12 µg/m3

Tesla tested its system in a confined space polluted with 1,000 µg/m3 full of PM2.5 (smaller inhalable particles than PM10).

Its system cleaned up the air inside the cabin to an "undetectable" level.

So I believe the answer is:

Yes, Tesla system does filter out photochemical smog effectively.

 

[gearchruncher]

I know you deeply want to believe that your filter will help with Photochemical smog, but until you find a reference showing that this smog is made up of particles at ground level, then there's no basis for this.

Yes, smog with particle sizes of 0.1 will be filtered. But this is not what you are asking about.

I'm not saying the HEPA doesn't work. But HEPA doesn't filter everything out. If it did, you'd die because oxygen is as much a chemical as ozone or carbon monoxide is. If you can invent a simple $100 filter that only lets oxygen through, you'll make Elon look like a pauper as you instantly make every ICE care about 3X more efficient.

 

[EarlyAdopter]

I know you deeply want to believe that your filter will help with Photochemical smog, but until you find a reference showing that this smog is made up of particles at ground level, then there's no basis for this.

Yes, smog with particle sizes of 0.1 will be filtered. But this is not what you are asking about.

I'm not saying the HEPA doesn't work. But HEPA doesn't filter everything out. If it did, you'd die because oxygen is as much a chemical as ozone or carbon monoxide is. If you can invent a simple $100 filter that only lets oxygen through, you'll make Elon look like a pauper as you instantly make every ICE care about 3X more efficient.

Actually, a $100 activated carbon filter is plenty effective at removing ozone. O3 is highly reactive, O2 is not so it passes through the filter material.

Ozone Removal by Filters Containing Activated Carbon: A Pilot Study (Conference) | SciTech Connect

Unfortunately, that was invented decades ago so someone else made those millions already.

The Tesla Bioweapons Defense Mode system consists of a HEPA filter + activated carbon filters.

 

[gearchruncher]

All Model X cars have the carbon filters,not just the bioweapon ones.

The title is "Photochemical smog and HEPA filter effectiveness"

 

[Tam]

All Model X cars have the carbon filters,not just the bioweapon ones..

Should that be for all $4,500 Premium Upgrades Package Model X?

For $4,500 more, you'll get: "Two activated carbon air purification filters that prevent nitrogen oxides and hydrocarbon exhaust fumes and other offensive odors from entering the cabin."

I agree that HEPA alone is not enough so Tesla does add activated carbon as well.

I don't know whether Tesla uses or not an additional option of electrostatic attraction to promote Particulate Matter binding.

 

[gearchruncher]

When they offered the Bioweapoon retrofit, the page said:

“Retrofit your Model X with the enhanced air quality package. This package includes Bioweapon Defense Mode functionality enabled and a new HEPA filter. Replace your current filter with a HEPA filter that is capable of providing cleaner air within the Model X cabin when compared to the outside atmosphere.”

Notice all it added was the HEPA filter and the software. The carbon filters are already there on all cars.

 

[croman]

When they offered the Bioweapoon retrofit, the page said:

“Retrofit your Model X with the enhanced air quality package. This package includes Bioweapon Defense Mode functionality enabled and a new HEPA filter. Replace your current filter with a HEPA filter that is capable of providing cleaner air within the Model X cabin when compared to the outside atmosphere.”

Notice all it added was the HEPA filter and the software. The carbon filters are already there on all cars.

Yes they also added an additional carbon post filter to all refresh cars but it works best with the giant HEPA.

I believe the system should effectively remove photochemical smog from cabin air. That is an intended purpose of the system, especially in places like China and India where the air is toxic.

 

[X Fan]

Due to a very dry winter, Southwest Florida had an awful fire season.

The X did a great job keeping smoke out of cabin.

 

[Tam]

...Notice all it added was the HEPA filter and the software. The carbon filters are already there on all cars.

That is one way to interpret the description but on the other hand, a HEPA filter might look normal:

But it's actually an integrated activated carbon with HEPA system which in this picture below includes 3 layers from 1 to 3 for the air to go through:

Logically, it costs more to add activated carbon filter so if owners don't pay extra, I don't see how Tesla would include them as a base price.

 

[vandacca]

During the Model-X reveal, Elon came on stage with the big HEPA filter in hand. It is mostly rectangular. The carbon filters are separate, but I have never seen them to know what they look like.

 

[EarlyAdopter]

There's no reason there couldn't be a carbon filter layer on the back, behind the white HEPA filter. I have a Blue Air in-room filter that has exactly that as an optional filter replacement (their "SmokeStop" filter) - front of filter is HEPA, back side is carbon.

 

[Tam]

There's no reason there couldn't be a carbon filter layer on the back, behind the white HEPA filter. I have a Blue Air in-room filter that has exactly that as an optional filter replacement (their "SmokeStop" filter) - front of filter is HEPA, back side is carbon.

I agree.

I just took a look at the launch event again and Tesla called its filter as "First True HEPA Filter"

that has 3 layers of activated carbon:

1) Universal Absorbent (Hydrocarbons)
2) Acidic Gases (Sulfur)
3) Alkaline Gases (Amonia)