Ambient air has an odor after removing respirator

I have noticed that after wearing a respirator (dual-cartridge activated charcoal by 3M) for an hour or so, when I remove it, the ambient air smells slightly sweet, almost like slight hint of ozone. After a little while without it, the smell seems to "go back to neutral" or nothing unique. I realize there is ozone in the air, but am surprised it'd be enough to smell, and it may not be ozone at all. However, I am assuming it is some kind of an "old-nose" type of thing, the respirator blocks all odors for an extended period, and then I am suddenly exposed to it again... maybe? Anyone have any ideas?

Yeah, it's not that the normal air has changed in any way obviously, it's that your nose sensitivity has changed slightly and your experience w/ that might differ from someone else's. That is, what you are experiencing might not be the same thing someone else does.

mp3car said:

I have noticed that after wearing a respirator (dual-cartridge activated charcoal by 3M) for an hour or so, when I remove it, the ambient air smells slightly sweet, almost like slight hint of ozone. After a little while without it, the smell seems to "go back to neutral" or nothing unique. I realize there is ozone in the air, but am surprised it'd be enough to smell, and it may not be ozone at all. However, I am assuming it is some kind of an "old-nose" type of thing, the respirator blocks all odors for an extended period, and then I am suddenly exposed to it again... maybe? Anyone have any ideas?

I am not a biology person, but looking at this from a Physics point of view, you nose is a collection of sensors.
The respirator filters out things in the air that would normally send signals to your brain, which filters
out a signal from all the noise.
Removing the respirator gives you a burst of what is now a "unique" smell, which after several minuets,
is no longer unique, and so you brain moves it to the noise category.

When I go for a walk in the park, I notice that after walking through a natural area with no cars, I can clearly smell the exhaust from the next car that I encounter with unusual pungency.

It's probably the same effect: after smelling pure air your nose is primed to detect unclean air.

mp3car said:

I have noticed that after wearing a respirator (dual-cartridge activated charcoal by 3M) for an hour or so, when I remove it, the ambient air smells slightly sweet, almost like slight hint of ozone. After a little while without it, the smell seems to "go back to neutral" or nothing unique. I realize there is ozone in the air, but am surprised it'd be enough to smell, and it may not be ozone at all. However, I am assuming it is some kind of an "old-nose" type of thing, the respirator blocks all odors for an extended period, and then I am suddenly exposed to it again... maybe? Anyone have any ideas?

I just wanted to let know that it is the same for me after wearing for few minutes only my 3M mask with pink cartridge . The odor seems to be ozone as well.

I used to work on ships at sea.
The ocean has an odor . ships have an odor.
And when you go back into port you can smell that too.

Smell is a kind of relativistic sense.
If you're around an odor for a while, you ability to smell or notice goes way down.

Its a complicated sense that is not fully understood.
It takes some extreme measures to work with it in a lab:

The smell of the sea seems to be dimethyl sulfide, produced by photo plankton, rather than ozone. No doubt this is removed by the filter. Another possible explanation is that, like all the body's sensors, the olfactory does not have a fixed reference available to it, and likely uses a long term average to set its neutral point. So when you remove the mask, the nose will take a time to re-calibrate to zero.

The first post is so familiar I thought I had written it.

I had the exact same experience with my CPAP mask. Sweet smell and all.

Perhaps the nasal equivalent of spending some time aligning a UV spectrometer lamp while wearing UV-appropriate 'green' goggles ?
At first, everything looks weird. After a while, the brain adjusts, the room's colours lose that 'Kermit' cast, look normal. Remove goggles and, well, be grateful that lunch is a five minute walk away, by which time the world will lose that candy-pink hue and look normal again...

FWIW, I'm reminded of an AC Clarke tale, where month-stay Lunar astronauts died of thirst because they became unable to tolerate their recycled water's taste...
Though repeated tests showed no contaminants, it tasted wrong,,,
In fact, it was so well distilled etc, it lacked any taste beyond a tang due to dissolved oxygen, whose sparkle made it unpalatable...
Had they or Control realised, they could have easily vacuum-degassed (*) it, and/or devised a simple way to sufficiently purge with a dash of CO₂...

*) Employ anti-bumping granules or magnetic stirrer, allow sufficient head-space, use Due Care, please...

Soon after WW2 some people had converted radar sets to watch (monochrome) TV, with a green phosphor screen. After an evening's viewing, people were reporting seeing a pink moon.

Nik_2213 said:

In fact, it was so well distilled etc, it lacked any taste beyond a tang due to dissolved oxygen, whose sparkle made it unpalatable...

Interesting. James Orgill, PhD, the ActionLab guy, wanted to test if pure water had a taste and drank a small amount of Type II de-ionized (5ppb sodium) water and ... among other things, burned his tongue (by cellular osmosis).

"...wanted to test if pure water had a taste..."

Our labs had both 'trad' glass stills and DI+RO units. The output from either system was best described as 'utterly boring'. No weird tongue-frazzling...

FWIW, the water was not drunk within the labs, but used to rinse then fill 'hiking bottles' for consumption else-where.

Nik_2213 said:

"...wanted to test if pure water had a taste..."

Our labs had both 'trad' glass stills and DI+RO units. The output from either system was best described as 'utterly boring'. No weird tongue-frazzling...

FWIW, the water was not drunk within the labs, but used to rinse then fill 'hiking bottles' for consumption else-where.

Yeah. The deionized water James is using is called Type II, which are, if I recall, distilled 5 times, getting the sodium content down way below the saline content of the human body. This causes cells to 'splode from osmosis.

That's odd, because oral mucus usually prevents such effects. IMHO, difference between one careful distillation and the five quoted is minimal in this context. IIRC, you need extended immersion to make skin 'bloat' thus, usually aided by soap and/or abrasion to remove 'barrier' skin oils...

Uh, does James have a skin-problem with mist or rain ?? As-is, his report borders on [H-word Redacted] claims for 'Infinite Dilution'...

Nik_2213 said:

That's odd, because oral mucus usually prevents such effects. IMHO, difference between one careful distillation and the five quoted is minimal in this context. IIRC, you need extended immersion to make skin 'bloat' thus, usually aided by soap and/or abrasion to remove 'barrier' skin oils...

??

Who soaps their tongue?

If molecules weren't making their way through any mucous barriers to the receptors in our tongues we wouldn't be able to taste at all.

Nik_2213 said:

Uh, does James have a skin-problem with mist or rain ?? As-is, his report borders on [H-word Redacted] claims for 'Infinite Dilution'...

Either you are misinterpreting James' experience, or I have seriously misled you. This has nothing to do with the H-word.

IIRC, even potable tap water is sufficiently low-ion to produce osmotic effects, hence skin-bloat after extended soak in fresh-water bath, lake or river. In this context, triple, quadruple or more distillations, supposedly 'pushing the nines', would make scant difference to water quality, provided 'still has proper reflux system and spray catcher.

( I'll give James the benefit of doubt regarding his distillation tech vs inefficient 'hillbilly' moonshine retorts... )

No, IMHO, there is something seriously amiss with James' correlation of water purity with that tingly sensation.

I suspect he's tasting dissolved gas, probably oxygen, not absence of eg salt.

As I mentioned above, our labs had both distillation and DI/RO systems for 'Analytical Grade' water, and the output from both was utterly bland. No tongue tingles...

Nik_2213 said:

I suspect he's tasting dissolved gas, probably oxygen, not absence of eg salt.

To be clear, I was more interested in his epilogue, where he mentioned the following day that it felt like he'd burned his tongue.

DaveC426913 said:

Interesting. James Orgill, PhD, the ActionLab guy, wanted to test if pure water had a taste and drank a small amount of Type II de-ionized (5ppb sodium) water and ... among other things, burned his tongue (by cellular osmosis).

I'm not certain we should take much stock in an uncontrolled, unblind experiment consisting of a single, self-dosing subject who mentions hearing rumors about danger before even starting, potentially predisposing him to hypochondria, who doesn't mention any symptoms during the experiment but only later, after consuming who knows what other beverages or foods or exposure to other substances, and who relies on interesting things happening to increase views and therefore Youtube ad revenue.

Also not at all impressed with his video's inclusion of a white blood cell bursting in water. WBCs spend their entire lives in blood plasma or interstitial fluid with high salt concentrations, and aren't prepared to be isolated in low-ion water, whereas the cells comprising the outer layers of the mucosal membranes are prepared - it's their job to handle a huge variety of concentrations. Also, mucosal membranes have incredibly rich blood supplies incredibly close to the surface. Any salt loss on one side of the surface layer will be resupplied by blood on the other side.

The mathematics of osmotic pressure Π. Π = icRT where i and R are constants, c is solute molar concentration, and T is absolute temperature. Blood solute molarity is about 0.3 M (we'll use this as the intracellular solute molarity). Typical drinking water has a salt concentration of 100 ppm. Assuming it's all sodium chloride for convenience, the solute molarity is 0.0034 M. What's important in terms of cell-bursting is the osmotic pressure difference between tap water and intracellular fluid, but one is only 1.1% as big as the other. If we were to replace the tap water with Type II deionized water, it would only increase the osmotic pressure difference by about that amount, 1.1%. I find this small amount of extra pressure extremely unlikely to cause cell damage.

And this explains why millions of gallons of distilled water are sold around the world without any label warning of tissue damage and why there isn't a flood of reports of people burning their mouths with it. It just doesn't happen.

Barakn said:

I'm not certain we should take much stock in an uncontrolled, unblind experiment consisting of a single, self-dosing subject who mentions hearing rumors about danger before even starting, potentially predisposing him to hypochondria, who doesn't mention any symptoms during the experiment but only later, after consuming who knows what other beverages or foods or exposure to other substances, and who relies on interesting things happening to increase views and therefore Youtube ad revenue.

Talk about attempting to poison the well!

I've been follwing this guy for years. He does good (pop) science and is as forthright as they come. You might want to watch more than one or two minutes before attempting to make such a broad judgement.

How are your experiments going, Mr. Armchair critic?

Barakn said:

And this explains why millions of gallons of distilled water are sold around the world without any label warning of tissue damage and why there isn't a flood of reports of people burning their mouths with it. It just doesn't happen.

It's not just any distilled water. He's pretty clear on that. (You did watch the video, did you not?)

DaveC426913 said:

any distilled water.

????

Bystander said:

????

The de-ionized water James is using is Type II, it is de-ionized multiple times until it's below the typical threshold - this is for lab work, not for consumption. (He says it's about 4,000 times more pure than bottled water. 5ppb Na)

So Barackn's speculation about "...millions of gallons of distilled water are sold around the world without any label warning of tissue damage and why there isn't a flood of reports of people burning their mouths" is off-base.

(Note: I should not have used the terms 'distilled' and 'de-ionized' interchangeably. Perhaps that is part of the confusion. )

"There a several types of water purity available depending on the application for which it is required, from Primary Grade Water (Type III) for simple washing and rinsing, to Purified Water (Type II) for general laboratory use, and Ultrapure Water (ASTM Type I) for highly sensitive applications."
https://www.evoqua.com/en-GB/articles/high-purity-water-a-technical-guide-to-types-i-ii--iii

"Deionized water contains no mineral ions. While this unique property makes it ideal for specific applications, it might not be suitable for drinking. "
https://www.springwellwater.com/deionized-water-benefits-risks/

Well, gave up and watched it; "...bitter...," he said. Alkaline earths are described as tasting "bitter," also used in "regeneration" of de-ionization resins. Mystery solved---he drank lye.

{ Face-Palm ...}

DaveC426913 said:

The de-ionized water James is using is Type II, it is de-ionized multiple times until it's below the typical threshold - this is for lab work, not for consumption. (He says it's about 4,000 times more pure than bottled water. 5ppb Na)

So Barackn's speculation about "...millions of gallons of distilled water are sold around the world without any label warning of tissue damage and why there isn't a flood of reports of people burning their mouths" is off-base.

(Note: I should not have used the terms 'distilled' and 'de-ionized' interchangeably. Perhaps that is part of the confusion. )

There's no confusion. Though the production method is different, the results are the same, a vast reduction in ions (your link says that even in distillation "99.9 percent of salts, minerals, and other organic and inorganic matter is removed)." Keeping in mind that osmotic pressure is linearly proportional to solute concentration, the Π_distilled = 0.001 x Π_bottled, and therefore the equation for osmotic pressure difference across a membrane separating bottled water from distilled, ΔΠ, is
ΔΠ = Π_bottled - Π_distilled = Π_bottled - 0.001 x Π_bottled
= 0.999 Π_bottled ~= Π_bottled

If bottled water contains 50 mg/l of sodium, for convenience, i.e. 50 ppm, then for a similar setup of a membrane separating bottled water from DI water, Π_DI = 5 ppb/ 50 ppm x Π_bottled = 0.0001 Π_bottled
and ΔΠ = Π_bottled - Π_DI = Π_bottled - 0.0001 x Π_bottled
= 0.9999 Π_bottled ~= Π_bottled

Even for tap water, the osmotic pressure of either single-distilled or DI water is comparatively negligible, and thus distilled and DI water are more like each other than they are to tap water. And this is even more so when comparing them to much saltier bodily fluids. It is flawed thinking to assume there's going to be a noticeable difference drinking distilled vs DI water, at least from the point of view of osmotic pressure. Note that I'm not saying there couldn't be some other effect at play.

OK, so we've got one data point of experiment (which has been called into question). We should probably do an independent experiment to either support or refute it.

I used to buy distilled water for drinking at home. I remember one time a friend who was a medical student told me it would kill me if I drank a liter of it. I drank a liter in front of her. I was going through a gallon a day. Then she told me I probably wasn't getting enough minerals. Good grief.