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oxygen
Posted: Jul 14 2010 6:10 pm
by joebartels
Curious if anyone here knows if there's truth in these statements?
wrote:Today's air contains less than 21% oxygen while in previous years our breathable air once contained more than 50% oxygen
wrote:Current research indicates there are over 60,000 more toxic chemicals in the atmosphere than detected ten years ago.
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It has been reported that LA smog is equivalent to smoking four packs of cigarettes a day.
The number one cause of COPD (Chronic Obstructive Pulmonary Disease) is smoking — in LA its not “required” to be a smoker to be highly susceptible to this disease that commonly includes Emphysema and Chronic Bronchitis.
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Reportedly our atmosphere contains about 20% oxygen. True, under ideal circumstances – and in the right locations.
When heavily polluted cities report it dropping down to 9% and 10% many hundreds of people with weak immune systems (the sick), die daily under these conditions.
Re: oxygen
Posted: Jul 14 2010 6:12 pm
by azbackpackr
It sounds a bit extreme, the variance in the numbers. Call me a skeptic. Also, call me if you find out more.
Re: oxygen
Posted: Jul 14 2010 6:14 pm
by joebartels
Re: oxygen
Posted: Jul 14 2010 7:42 pm
by Al_HikesAZ
joe bartels wrote:Curious if anyone here knows if there's truth in these statements?
Today's air contains less than 21% oxygen while in previous years our breathable air once contained more than 50% oxygen
Back in the carboniferous period about 350 million years ago, breathable air may have approached 50% oxygen, but there weren't any humans around to breath it or measure it. For the last couple of million years it's been just under 21%. If you can't trust Wikianswers, who can you trust:
http://wiki.answers.com/Q/Is_there_less ... sphere_now
Is there less oxygen in the atmosphere now?
In: Earth Sciences, Zoology or Animal Biology, Human Anatomy [Edit categories]
A: [Improve]
There is less oxygen in the atmosphere now than there was in the carboniferous, about 350 million years ago.
Oxygen levels have remained fairly constant over the past few million years, and there is no reason to believe the level is rising or falling abnormally. Oxygen in our atmosphere is largely liberated by photosynthetic cyanobacteria in our oceans. Trees are another good source, and although we have deforested millions of acres, there is little evidence this has had much impact on earth's oxygen level.
I would like to believe that there is less oxygen. Then I could blame my slower hiking speeds on science instead of my OLD AGE!!! The percentage of oxygen stays the same at different elevations, but the density decreases with elevation. So less density, less total oxygen even at the same percentage. And our VO2Max decreases with age.
I have been at meetings where certain people enter a room and suck all of the oxygen out of it.
Re: oxygen
Posted: Jul 14 2010 8:09 pm
by hikeaz
Since he's near LA, that could be Mel's #11 answer on Dave's Top Ten List........ "It wasn't my fault, I was oxygen deprived"......... (further corroborated by the huffing and puffing)
Re: oxygen
Posted: Jul 14 2010 8:09 pm
by Jeffshadows
There is some truth in those statements. One of the industrial hygiene guys I work with used to work for ADOT and they would have to pull guys out of pits and low-lying projects in the mornings sometimes up in Phoenix who had lost consciousness because of smog build-up in the confined space.
For more edification, this came straight out of textbook used at UA:
Local weather patterns also interact with and affect air pollution. Rain and snow carry atmospheric pollutants to Earth. Temperature inversions, like the conditions that caused London's Great Smog in 1952, occur when air near the Earth's surface is colder than air aloft. Cold air is heavier than warm air, so temperature inversions limit vertical mixing and trap pollutants near Earth's surface. Such conditions are often found at night and during the winter months. Stagnation events characterized by weak winds are frequent during summer and can lead to accumulation of pollutants over several days.
To see the close connections between weather, climate, and air pollution, consider Los Angeles, whose severe air quality problems stem partly from its physical setting and weather patterns. Los Angeles sits in a bowl, ringed by mountains to the north and east that trap pollutants in the urban basin. In warm weather, cool sea breezes are drawn onshore at ground level, creating temperature inversions that prevent pollutants from rising and dissipating. The region's diverse manufacturing and industrial emitters and millions of cars and trucks produce copious primary air pollutants that mix in its air space to form photochemical smog.
Re: oxygen
Posted: Jul 15 2010 5:58 am
by azbackpackr
With all those extra pollutants in and around cities, I am glad I live up here in the Redneck Alps. I just have to breathe methane from cow poop.
Re: oxygen
Posted: Jul 15 2010 6:35 am
by johnlp
I don't believe most of what is quoted above. Below 10% oxygen concentration and you may lose consciousness according to NIOSH. Confined space entry training dictates that below 19.5% requires supplied air to be safe. At 50% oxygen levels one could only imagine what the wildfire season would be like.
Re: oxygen
Posted: Jul 15 2010 7:12 am
by DarthStiller
I remember that also from confined space entry training. There is also an upper level that I believe is way less than 50% at which point it becomes an explosion hazard. wikipedia should have the official info on this, with the links to back them up.
Re: oxygen
Posted: Jul 15 2010 7:19 am
by PaleoRob
I know that oxygen content from the Paleozoic, specifically the Carboniferous Period, was higher than today, but I didn't think it was 50%, since CO2 was also much higher. Wikipedia lists O2 content at roughly 35% during the C.
Re: oxygen
Posted: Jul 15 2010 10:17 am
by DarthStiller
The upper limit oxygen content for confined space entry is 23.5%, which is to say that a content higher than that is not healthy for humans. The main misnomer in your original quote Joe is where it says breathable air is 50%. 50% oxygen isn't breathable for humans.
( dead link removed )
Re: oxygen
Posted: Jul 15 2010 10:28 am
by joebartels
I anticipated those figures were questionable since they're advertising leads. Then wondered what truth had been mangled.
thanks!
Thought Preston would jump in considering he delivers it. No dice, he's probably out there suckin' down a bottle and getting taller while we write.
At any rate, then maybe we've lost 5-10% of the oxygen?
Re: oxygen
Posted: Jul 15 2010 10:37 am
by Al_HikesAZ
joe bartels wrote:At any rate, then maybe we've lost 5-10% of the oxygen?
Maybe - over the last couple of million years. Not in our lifetimes. Stiller's info is referring to "confined spaces".
Re: oxygen
Posted: Jul 15 2010 10:38 am
by Jeffshadows
joe bartels wrote:At any rate, then maybe we've lost 5-10% of the oxygen?
It probably depends on location since the concentration (Partial pressure) of O2 should be steady (~22%) unless there is something in the air to use it up or out-compete it.
Re: oxygen
Posted: Jul 15 2010 11:20 am
by Jim
Joe, are you telling me you found bad information on the internet?! I am shocked, shocked, I say, at this revelation.
Re: oxygen
Posted: Jul 15 2010 1:44 pm
by azbackpackr
Jim_H wrote:Joe, are you telling me you found bad information on the internet?! I am shocked, shocked, I say, at this revelation.
Re: oxygen
Posted: Jul 15 2010 2:37 pm
by Jeffshadows
Jim_H wrote:Joe, are you telling me you found bad information on the internet?! I am shocked, shocked, I say, at this revelation.
You mean I'm not getting an inheritance from a Nigerian bank?
Re: oxygen
Posted: Jul 15 2010 4:59 pm
by paulhubbard
Yeah, and I had my UK Lottery winnings spent already...
Re: oxygen
Posted: Jul 15 2010 5:15 pm
by PaleoRob
joe bartels wrote:
At any rate, then maybe we've lost 5-10% of the oxygen?
The amount of oxygen is basically constant - no new oxygen is arriving on earth. The question is how much of the earth's oxygen (of which nearly all is locked up as SiO2) is in the free O2 form, not combined with Carbon, Nitrogen, or Hydrogen, to name a couple popular suspects.
Re: oxygen
Posted: Jul 15 2010 9:29 pm
by Jim
PageRob wrote:
The amount of oxygen is basically constant - no new oxygen is arriving on earth.
Tell that to those pesky ice meteorites. Oxygen being in water and all.
Nah, I know the amount arriving to Earth is trivial. Still oxygen levels could be rising or falling slightly, since we do use a lot of Iron, and the oxygen we have today was produced as a waste product from bacteria which released in through chemical reactions that deposited are large iron deposits on the surface, but that was eons ago, long before a vertebrate ever swam the seas. My point though is that rust consumes oxygen and that could release or consume it depending on which was the iron and oxygen are going. I doubt that it makes much difference.