[Julia (OP)]

I have acquired an allergy or sensitivity to some chemical that is used in many colognes and aftershaves. I have narrowed it down to a chemical because I don't react to all scents and I can stand cigarette smoke and all sorts of other things that regularly allergic people find offensive. I find riding on the bus to work in the morning almost unbearable because everyone on the bus has just applied their scent for the day and I am overwhelmed. I have decided to get a mask and that is why I am writing - to find out what size are common "scent molecules". When we had the SARS scare, the CBC did a test on masks to see which would filter out particles of 0.3 microns. The N95s mask that can be bought in drug stores did the trick. If scent molecules are larger than this, then I can use a simple mask on the bus.

[chris]

For general information about smells and odours and how the nose works (olfaction) check out Peter's smell page (produced for his appearance on the programme recently) :

http://www.thenakedscientists.com/smells

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[Ylide]

I would think that scent molecules (generally esters) would be smaller than 0.3 microns.  Those SARS masks are designed to keep out biological molecules, which tend to be rather huge.  A virus, while tiny, is still thousands and thousands of atom.  A typical ester would have maybe 20-80 atoms.  It's size would be on the order of a nanometer or two, depending on structure.



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[bezoar]

But those masks aren't airtight on your face.  How can they protect against SARS?

[Ylide]

They're not 100% protection, but they're better than nothing.  The bulk of the air that flows through them is via the mesh and not the edges where your face meets the mask.  They do offer some degree of protection, but it's not fool proof of course.  You'd need a fully enclosed gas mask to really be safe, but who wants to walk around with one of those on all the time?

Funny story, back in my organic chemistry lab, one of the asian students would wear one of those small white fabric masks like they wore in China to protect from SARS.  We didn't have the heart to tell her that most of the organic compunds we were working with would freely permeate that mask and that all it really did was make her look stupid.





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[bezoar]

Ah, but i"ll bet she hasn't gotten SARS.  Did you see that there's quite an outbreak expected?  Maybe she was just ahead of her time.

I guess the surgical masks work on the same principle.  So then, if you have to sneeze while operating, you shouldn't turn your head, lest the sneeze escape out the sides of the mask on to the surgical field, right?

[Ylide]

This was in the US, in Denver, Colorado.  Not much SARS around here.  



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[chris]

Whilst I was in Japan over Christmas in 2001 I was surprised to see that I was sharing a train carriage with about 50 surgeons - or at least that's what they looked like all decked out in face masks. Turns out that, out of politeness, anyone with a cold dons a surgical face mask to prevent anyone else catching their cold.

The fact that the majority of the passengers were wearing one was testimony to their ineffectiveness !

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[Ylide]

Japan is so densely crowded in its urban areas, I'm surprised a major contagious illness hasn't wiped them out yet.  The streets, the subway, bars, and the like are usually shoulder to shoulder people, according to a friend of mine who spent a year there.  There's just no distancing yourself from other people...I don't know how they stand it.

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[chris]

Some would argue that living in close quarters like that is actually protective because everyone's immune system seems a huge variety of different infectious agents regularly. Hence you maintain extremely good background immunity without becoming seriously unwell.

The flu this year was a bad one because we have had a few good years when no one got flu. As a result there was a large cohort of young people wandering around with ill-educated immune systems and hence an increased susceptibility to flu infection. When it arrived they had very poor background / basal immunity and hence an immune response had to be mounted from scratch. Some people succumbed before they had a chance to clear the infection.

That said, your point about living in close quarters is significant and has contributed to a large number of outbreaks worldwide. The TB epidemic in Asia is a prime example.

Chris

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

[bezoar]

Aren't we supposed to be overdue for a flu epidemic.  Was the last one some time in the 1920's when so many otherwise healthy, young people died?

[tweener]

I don't believe the little paper masks do any good for much of anything.  They keep out the large dust particles that clog your nose, but let the tiny stuff through (the stuff that really damages your lungs).  That's my belief anyway.

In terms of filtering out the organic vapors, I bought a real respirator with the dual filters and a sealing face mask.  It is great!  I can paint for hours and not even smell it.  They cost about $20 but are well worth it.  Whether you'd want to wear one in public is another matter entirely!


----
John

[Ylide]

I wish I had even one of the little paper masks today.  I was prepping "unknown" mixtures for the organic lab students to practice recrystallization techniques on and ended up inhaling a significant amount of particulate benzoic acid, oxalic acid, and salicyclic acid.  By the time I left campus, my lungs were burning, my chest was tight, and I could barely breathe.  It was so bad I called Poison Control when I got home so I could find out if I was in any serious danger.  (the good news is 15 minutes of steam and drinking lots of water helped)

I hope there's no long term damage =/



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[Weezer]

quote:Originally posted by Julia

I have acquired an allergy or sensitivity to some chemical that is used in many colognes and aftershaves. I have narrowed it down to a chemical because I don't react to all scents and I can stand cigarette smoke and all sorts of other things that regularly allergic people find offensive. I find riding on the bus to work in the morning almost unbearable because everyone on the bus has just applied their scent for the day and I am overwhelmed. I have decided to get a mask and that is why I am writing - to find out what size are common "scent molecules". When we had the SARS scare, the CBC did a test on masks to see which would filter out particles of 0.3 microns. The N95s mask that can be bought in drug stores did the trick. If scent molecules are larger than this, then I can use a simple mask on the bus.

[Weezer]

Julia,
I have the identical problem that you have.  I can sit in a room full of smokers, and although I don't particularly care for it, the smoke does not bother me.  Then, a person walks behind me (If know this person to be "smelly",I have learned to breath shallow in their presence) my throat slams shut and I am caught gasping for air until an albuterol inhaler can open my airway.  My son is doing his science fair project using me as the subject (He considered calling it "Freak of Nature")  My question, forgive my ignorance, is what is the difference between the offending molecules vs. the non-offensive molecules?  Is it simply that we are allergic to specific ones?  Do stronger scents contain more molecules than those with little or no scent?  Thanking all who respond in advance for helping a graphic designer with no scientific background and her innocent (not) 13 year old.

[Weezer]

Julia,
I have the identical problem that you have.  I can sit in a room full of smokers, and although I don't particularly care for it, the smoke does not bother me.  Then, a person walks behind me (If know this person to be "smelly",I have learned to breath shallow in their presence) my throat slams shut and I am caught gasping for air until an albuterol inhaler can open my airway.  My son is doing his science fair project using me as the subject (He considered calling it "Freak of Nature")  My question, forgive my ignorance, is what is the difference between the offending molecules vs. the non-offensive molecules?  Is it simply that we are allergic to specific ones?  Do stronger scents contain more molecules than those with little or no scent?  Thanking all who respond in advance for helping a graphic designer with no scientific background and her innocent (not) 13 year old.

[Ylide]

Sounds like an allergy to me.  Body odor is the byproduct of bacterial breakdown of skin cells.  The armpits and groin just give them a nice warm place to live where they won't get brushed off easily.  I'm not 100% sure of the molecular contents of body odor, but I'm guessing things like butyric acid or some sulfides.  These are quite differente from the products of combustion.

Everyone's body has different reactions to different "intruders"

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[Donnah]

When I get hot flashes I sometimes sweat profusely in my armpits.  I have to wash immediately because that sweat reeks like a room after it's been jammed full of beer swilling, stinky sock men.  Why does the sweat from hot flashes smell so different than normal sweat?  Obviously there's a hormonal influence, but how does that work?

[Ylide]

I have no idea on that Donnah...that sounds like one for Chris.  I would hypothesize that the hormones that are triggering the hot flash are breaking down into something stinky and being emitted, much in the way a pubescent teen has a more distinct odor at times.



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[bezoar]

Maybe that ties into why the exboyfriend's son who was hooked on anabolic steroids smelled so bad.  Maybe the hormones increase the smell.