Tainted Atmospheres

[rancke]

The bottom line is simple, Hans, whoever wrote the BTC thing was writing a game, not a scientific treatise. ie they made it up. Your best option is to do the same. It may not even be possible for it to make sense scientifically. Just wave your hand.

I'm making an effort to make the canonical taint work. That it, to figure out what in the Travellerverse "tainted by lighter gases" actually means, in game terms and in background terms. Personally, I'd much prefer to make it a fairly negligble industrial taint, but I am trying to be faithful to previously published information.

If it turns out that it IS impossible to make it make sense scientifically, I may have a shot at persuading TPTB to let me change it. But before I try that, I thought I'd try to see if it could work.


Hans

 

[G. Kashkanun Anderson]

I'm afraid that doesn't help me much. What effects? And where would they be released?

Tectonic activity releases Helium, which apparently is locked in the Earth's mantle in fairly substantial quantities. The Siberian Traps of the Permian Era, a magma field roughly the size of Scandinavia, released all kinds of gases into the Earth's atmosphere -- mostly carbon dioxide, but plenty of helium came out, too. I suppose hydrogen is a given. All of it definitely gave the atmosphere a 'taint', since about 95% of the species then alive died out at the time.

I assumed these lighter gases were part of the air mix. If they're lighter than air, wouldn't concentrations go straight up without contaminating the air?

I imagine helium would be gone in a geological blink of an eye; but that could still be thousands of years on a human scale. If the magma fields have been active for a few hundred thousand years or so, there should be an equilibrium in place between how much helium is lost to space and how much keeps belching out of the planetary crust. Atmospheric convection should keep even the lighter gases globally dispersed, as long as they're still around.

What effect does hydrogen have on the human who breathes it? Helium is inert, so it would be harmless, wouldn't it?

Hydrogen has narcotic effects at certain levels. I'm unable to find out exactly what levels they are, though. It probably also varies depending on atmospheric pressure levels. I read somewhere that anything more than 18% atmospheric concentrations of hydrogen creates a distinct flammability problem; fortunately, I can't really imagine any terrestrial gravity well being able to hang on to that much hydrogen at temperatures above near cryogenic levels.

Helium is very inert on its own. The biggest threat it presents is to oxygen levels, simply by the fact that its mere presence could crowd the oxygen out to below usable levels.

This website on 'exotic diving gases' might be helpful in figuring out toxicity levels for theoretically breathable, non-terrestrial atmospheres. Hydreliox, a mixture of Hydrogen, helium & oxygen, is an exotic diving gas. If you can figure out more information on that, you might be able to work out a pretty interesting dense atmosphere taint.

 

[Starviking]

Hydrogen

Hydrogen is too reactive to be present in significant quantities in a breathable atmosphere at ground level. Helium is good though.

 

[rancke]

Hydrogen is too reactive to be present in significant quantities in a breathable atmosphere at ground level.

That's the impression I'd gotten too. Hence my problem.

Helium is good though.

What about neon?

Question: If the dense atmosphere of this world (it's Mora, BTW) has less oxygen than a baseline human is comfortable with (say, perfectly OK to breathe with normal exertion, but a problem with strenuous activity) and you had a filter that blocked the unusually high percentage of helium (and neon?) in the air, would that increase the partial pressure of oxygen?

It sounds very dodgy to me, but I'm desperately trying to come up with a reason to filter out those light gases (as opposed to carrying a compressor mask or an oxygen mask).

Even if it would work, you'd need some way to filter out helium and neon and let the oxygen through, wouldn't you?

Alternatively, could there be some other reason why visitors ought to be aware of the presence of those gases? That is, it's not a taint that requires filter masks, but you need to be careful flying grav vehicles. Or something...


Hans

 

[Icosahedron]

Hydrogen is too reactive to be present in significant quantities in a breathable atmosphere at ground level. Helium is good though.

That's the impression I'd gotten too. Hence my problem.

That probably assumes a fixed amount of Hydrogen that would vanish over time due to reactions and evaporation into space, but if the Hydrogen were being constantly replenished from volcanic vents, electrical storms, or whatever, then it might exist in significant quantities in a temporary equilibrium over a brief geological timescale.

What about neon?

Question: If the dense atmosphere of this world (it's Mora, BTW) has less oxygen than a baseline human is comfortable with (say, perfectly OK to breathe with normal exertion, but a problem with strenuous activity) and you had a filter that blocked the unusually high percentage of helium (and neon?) in the air, would that increase the partial pressure of oxygen?

It sounds very dodgy to me, but I'm desperately trying to come up with a reason to filter out those light gases (as opposed to carrying a compressor mask or an oxygen mask).

Even if it would work, you'd need some way to filter out helium and neon and let the oxygen through, wouldn't you?

IIRC, yes, removing the other gases would increase the partial pressure of Oxygen.

Neon comes after Oxygen in the periodic table, which may suggest that it has a larger and heavier atom. However, as a monatomic molecule it may be physically smaller and lighter than the O2 molecule. Therefore, some form of filter might be engineered that drew the smaller He and Ne molecules through a semi-porous diaphragm into an exhaust chamber, leaving O2 and N2 behind to be used?

OTOH, what is the definition of 'lighter gases'? IIRC Nitrogen is slightly lighter than Oxygen, so maybe there is an overabundance of N2 in the air, leading to some form of 'Nitrogen narcosis'? Not sure how you'd filter that out, though.

Alternatively, could there be some other reason why visitors ought to be aware of the presence of those gases? That is, it's not a taint that requires filter masks, but you need to be careful flying grav vehicles. Or something...

Yep, the abundance of Helium creates a society that has so many lighter than air craft that they form a barrage balloon type flying hazard to grav vehicles

 

[Peter Schutze]

<Helium is very inert on its own. The biggest threat it presents is to oxygen levels, simply by the fact that its mere presence could crowd the oxygen out to below usable levels.

yep except that after a certain pressure (usually above the traveller dense rating) the lungs have trouble getting the oxygen out even if there is sufficient amounts thus the need for various diving gas mixes

>so maybe there is an overabundance of N2 in the air

thats probably just going to cause a 'low oxygen percentage' taint in normal atmospheric densities / pressures

>'Nitrogen narcosis'?

Nitrogen narcosis is the most likely form on earth .... with different gas mixes you can get the same effects

Narcosis rating (Earth is 33%)
NE X0.13
H2 X 0.26
N2 X0.42
O2 X 0.71
AR X0.92
KR X3
CO2 X8.33
XE X10.67
N2O X10.79

multiply the atmospheric component percentage by the effect rating and the total by the pressure rating .... when the rating gets much over 33% expect narcosis effects

 

[JustinInOz]

Another Angle

Taint could very easily be some complex biologically generated molecule. The discussion so far has centred upon atomic/elemental gasses or gasses that are very simple molecules.

The biosphere of the world could be producing this as a byproduct of its metabolism.

To us it is taint. This requires the ususal precautions.

Could be something like the environment on Cyteen in the novel by CJ Cherryh. If you are not careful, the stuff will give you cancer.

 

[Duke Pellinor]

Jtas

I've just finished reading all the back issues of the journal, there were two really good articles back to back on world building that probably went into the World Builder's Handbook that give some good ideas on how to deal with just these issues. I can't remember the issue numbers and I'm too lazy to check, but if you have copies I recommend a thorough search as the articles were excellent. If you don't, buy the CD it's worth it (I'm currently waiting on mine)

 

[shaunhilburn]

I've rolled up a world with a dense tainted atmosphere and I've been trying to think up cool, at least somewhat "realistic" ideas about what that means.

Generally, taints are particulate or gaseous. Particulates require filter cannisters, gases require scrubber cannisters for a specific gas. Cannisters attach to the mask via hose, or directly to the mask.
There are two types of filter masks: full-face tactical/NBC (MCU-2/P, Scott M98, 3M 6000 series) primarily for gaseous taints, and half-face mainly for particulate taints (dust, ash, spores, pollen)

Common taints in a breathable atmosphere

Taint             Mask        OSHA PEL    Comment
--------------------------------------------------------------
Oxygen            Full face               Hyperoxia/oxygen toxicity and pulmonary distress within
                                          3 hours @ pO2 1,500 mm Hg, 48 hours @ 760 mm Hg
Carbon dioxide    Half face  5,000 ppm    Mild hypercapnia, discomfort @ 2%, dyspnea @ 4%, impairment/illness/
                                          headache @ 6%, unconsciousness in 10 min @ 10%, acidosis and rapid death @ 30%
Nitrogen          Half face               Narcosis begins @ pN2 2,000 mm Hg
Carbon monoxide   Half face     50 ppm    Strong affinity for hemoglobin, dangerous @ 100 ppm
Ozone             Full face    100 ppb    Eye, nose irritant, very unhealthy in small traces. Immediate hazard @ 5 ppm
Hydrogen sulfide  Full face     50 ppm    Volcanic gas or remnant of corrosive atmosphere, extreme rotten egg stench.
                                          CNS effects begin @ 5 ppm. Dizziness/headache/staggering/diarrhea 
                                          after 30 min @ 500 ppm. Eye irritant @ 100 ppm. Numbs sense of
                                          smell @ 50 - 100 ppm. Severe eye/lung irritant @ 200 ppm.
                                          Deadly @ 500 - 1,000 ppm
Sulfur dioxide    Full face      2 ppm    Volcanic gas or remnant of corrosive atmosphere, burnt match smell. Sneezing,
                                          coughing, burning eyes @ 10 ppm. Severe respiratory distress @ 20 ppm.
Dimethyl sulfide  Full face     10 ppm    Ocean smell produced by phytoplankton, irritant to eyes/nose/throat @ 10 ppm
Methanethiol      Full face     10 ppm    Algae metabolite with extreme rotten cabbage odor. Toxic in large concentrations.
Ammonia           Full face     50 ppm    Bilogical waste or remnant of corrosive atmosphere, sharp odor threshold @ 5 ppm. 
                                          Respirator required @ 25 ppm. Burns eyes/nose @ 100 ppm. Eye injury @ 700 ppm.
                                          Caustic to airway @ 1,000 ppm. Fatal after 30 min @ 2,500 ppm.
                                          Highly poisonous, caustic burning of living tissue. Cell membrane denaturant.

The OSHA Permissible Exposure Level is an 8-hour average. Concentrations are at 1 atmosphere (760 mm Hg)

Oxygen and nitrogen are only dangerous in dense atmospheres at high partial pressures (Atmosphere digit 9)

Sulfides, methanethiol, and ammonia have a very short lifetime in an oxidizing atmosphere, they must constantly be replenished.

 

[aramis]

Sulfides, Hydrogen, Methanethiol, Ammonia, Methane, and Sulpher Dioxide all occur as part of life-cycles as byproducts... and thus can be a life-form caused taint.

H2 ref
H2S ref
CH3SH (Methanethiol) & H2S ref
Ammonia Ref

 

[shaunhilburn]

Oxygen and nitrogen are only dangerous in dense atmospheres at high partial pressures (Atmosphere digit 9)

Let me add that the 'filter' for oxygen or nitrogen excess is similar to a SCUBA regulator. These gases aren't toxic, the mask only needs to regulate the dosage vs removing the 'taint'.

 

[aramis]

For molecular oxygen (O2), if it's high enough to be a hazard needing pressure regulation, it's also likely a major fire hazard if the atmosphere is not also dense. Other accomodations need to be made.

Ozone far less so, because the threshold for hazard is MUCH lower.

 

[shaunhilburn]

For molecular oxygen (O2), if it's high enough to be a hazard needing pressure regulation, it's also likely a major fire hazard if the atmosphere is not also dense.

Not necessarily. Respiration and combustion depend on slightly different factors.


The ability to support combustion is heavily dependent on the molar concentration of O2, e.g, the O2% and only slightly dependent on O2 partial pressure. At 1 atmosphere, flame extinction occurs around 15% O2.

The affinity for hemoglobin (breathability) is determined *soley* by the partial pressure of O2. This makes it possible to have breathable atmospheres that won't support flame, e.g. "flame-retardant atmospheres".

The US Navy's Sealab II experiment in the 1960s used a helium atmosphere at 7 Atm with about 4% O2. Diver's weren't able smoke cigarettes, the matches wouldn't even strike.

My notes (from some old fire code) indicate a flame-enhancing atmosphere exists if O2% > 23.45/sqrt(Atm).

 

[aramis]

Specifically, the sealab experiments did NOT use hazardous levels of O2. They used PPO2 below the taint range. At 7 atm, the PPO2 of surface mix (21%) would be 1.47Atm PPO2... well beyond toxic, and well into increased flame range (8.863266892066378% by your quoth formula). heck, that flame level would be 62% Atm PPO2... a level at is anoxic at sea level.

Oxygen toxicity starts at 50kpa , and significant damage at 60KPa. Short term exposure damage at 100KPa, and around 160kpa PPO2 results in convulsions...

Oh, and at 2.5 Atm, the peak for dense atmosphere as defined in Traveller, 50KPa is 19%, while fire risk is 14.8.
And Very Thin atmospheres can not hit oxygen toxicity, but still can hit increased fire risk.

 

[shaunhilburn]

For molecular oxygen (O2), if it's high enough to be a hazard needing pressure regulation, it's also likely a major fire hazard if the atmosphere is not also dense.

I ran the numbers, and you're right. Atmosphere 9 with excessive O2 taint is certainly fire enhancing.

Hyperoxic, flame-retardant atmospheres are almost always artificial, and are only possible at very high pressure - starting at 1,580 kPa.

That's ocean depth equivalent to 520 feet. I remember reading that, breathing at 8 atmospheres, the density is such that one can feel the turbulence and eddy currents in their mouth and nostrils.

 

[aramis]

Actually, sufficient PPO2 to cause oxygen toxicity without increased fire risk is somewhere around 3.7 Atm or so... at 4 Atm, there's almost a percent difference.

Atmospheres 5-9 can have excessive O2 for human health, and all of them will have crossed the increased fire risk before that point. Yes, I did the math, too... about 25 years ago. And again this morning.

 

[RockViper]

High levels of volcanic activity could contaminate the atmosphere just enough to require a respirator. The contaminant in this case would be ash and various volcanic gases.

I've rolled up a world with a dense tainted atmosphere and I've been trying to think up cool, at least somewhat "realistic" ideas about what that means.

The only documentation I have about tainted atmospheres is that they need a filter mask. Meanwhile, the planet is only TL3, which means they either import their masks, fashion crude ones that work (hmmm, some steampunk ideas here...) or the natives have built up some kind of immunity.

But the question remains... what is the contaminating agent?
Right now I'm going for spores from local flora/fungi life, but I was wondering what some of you planetary scientists think.

Thanks!

 

[boomslang]

The only documentation I have about tainted atmospheres is that they need a filter mask. Meanwhile, the planet is only TL3, which means they either import their masks, fashion crude ones that work (hmmm, some steampunk ideas here...) or the natives have built up some kind of immunity.

But the question remains... what is the contaminating agent?

Summarizing then, there are pretty much three, non-mutually-exclusive possibilities:

1. Some sort of gaseous contaminant. This will be the hardest to filter out at low TL, although a naturally-occuring gas-consuming sponge of some sort might be cultivated and fashioned into a replaceable filter mechanism for breathing masks. Tolerance or immunity will be difficult, but not impossible, for locals to evolve. The impact on the local biosphere may be complex.

2. Some sort of biological agent that is small enough to remain in airborne suspension, such as pollen or bacteria. These can perhaps be filtered by a physical barrier -- an exceptionally-finely-woven fabric mask, for example, perhaps with matching goggles -- but locals will need to take additional precautions to address contamination of household surfaces, foodstuffs, and the like. This sort of contaminant will be easier for locals to evolve a resistance or immunity to, and Travellers might have access to inoculation against it. As part of their own adaptation, local plants and animals might produce a biochemical that people could harvest and consume to help offset some of the harmful effects of the contaminant.

3. Some sort of mineral particulate, typically microfine dust from an erosion or eruption process. This is also filterable by a simple physical barrier and poses little threat to foodstuffs if washing is available, but it is also the most difficult to develop a tolerance for or immunity to.

 

[abomination]

(and maybe you get a squeaky voice, too. )

Possibly the natives (or long term residents) would talk normally but become James Earl Jones in a standard atmosphere. However I only have anecdotal evidence to support this.

 

[atpollard]

Too high of an oxygen content.

The cure is to rebreath come of your own carbon dioxide (like breathing into a paper bag to stop hyperventolating). The low tech mask doesn't need to be leak proof, it just needs to hold enough of your exhaled breath to compensate.

As an interesting aside, fire has some strange properties at higher O2 concentrations ... for example, wet wood will burn and the ignition point for combustion is lowered.