See subject. I thought I read that after a rain allergic reactions to all that ragweed, pollen, I don’t know what would temporarily ease up, because the stuff would be tamped down somehow.
All I know is it rained and my allergies have gone berserk.
Both, plus they carry down allergens with them, and of course lead to more pollen production. Rain storms bring wind as well as rain, so even if pollen is tamped down, more has been spread over a wider area, and it will dry out. IMHO, rain sucks.
So, in the absence of noticeably windy conditions, and before aridity, it does, or should “tamp down”–wash out and carry down–allergens from trees and plants, and thus temporarily lower the misery rate?
Because if that’s true I’ve got some serious contradictory anecdotal evidence.
Anecdotal: there was a period circa 2008 when it didn’t rain for 3-4 months here in the hot-arse SE United States. My allergies were extremely well behaved during those months. At the end of the stretch, we received a monstrous amount of rain for two days straight, and I got a sinus infection within days 
My doc posits that rain causes pollen to mass on the ground, which in turn gets moldy, making things even worse when all that junk gets airborne.
IANAD, but my understanding is rain tends to alleviate pollen allergy symptoms but worsen mold allergy symptoms. Since individuals may have a mix of specific pollen and mold allergies, the timing of the rain creates another variable. In my case, for example, I tend to react more to molds than pollens, so rainy periods, particularly in the autumn when there is a lot of leaf litter, can really get me to hurting. On the other hand, one pollen that gets me is maple. So when those strange little red maple flowers are in bloom, the rain actually brings some relief.
Complicating things is that barometric pressure can also play into it. I am more likely to have sinus pain (although not other allergy symptoms) when the pressure is low. I understand that this may be due to chronic swelling which higher pressure keeps in check.
To add to the anecdotal evidence:
I heard rain helped with allergies a few years ago. My gf suffers from pretty acute pollen allergies every spring, so since then I’ve tried to keep track of her complaints relative to how much its been rain.
So far as I can tell, there’s at best no effect and at worst their somewhat worse after a spell of rain.
Rain still carries down pollen from the atmosphere, and it carries down pollen that may not be local which you may be more sensitive to, sometimes just from lack of exposure. The changing air pressure kills my sinuses independent of the pollen.
The rain in your community may contain DHMO, and maybe you’re allergic to that. I’d get those possibilities checked out if I were you.
When the humidity rises, ie when it rains or is about to rain, pollen grains burst (the starch expands and bursts the grain), releasing protein fragments (allergens) into the environment.
And then everything bursts into flower.
I have developed a bit of sensitivity to pressure changes in the last few years. It’s quite annoying.
This plus with the increased humidity the ability for the atmosphere to carry heavier pollens comes into play. We see this on high humidity days as well.
I think this is correct. I only have my own experience to go by but my allergies can get worse after a rain.
Yes, rain absolutely knocks particulate pollution out of the air. Spring rains make my car absolutely filthy: pollen-choked raindrops hit it, then the rain dries out, leaving splotches of pollen all over it, despite not being parked near any trees.
The downside for allergic folk is that after the rain is done, the water makes plants emit an even more intense burst of pollen. So you get a brief period of “ah, much better” followed by “I want to die.”
My wife has seasonal allergies and is a professional expert on particulate air pollution; she’s the one that gave me this info.
So, yes, that part of the phenomenon, the knocking-pollen out out of the air, you’re saying (agreeing?) is a good thing for the allergy sufferer? That even though the amount of pollen liberated from the tree has jumped, since it is entrained in the rain and plastered to the earth it poses no threat?
I’m aware that upthread it was mentioned that once all that pollen is released on the ground–post aridity only, I take it–the threat is back.
Interesting. Lot of good facts in this thread.
You’re not speaking rhetorically here, she really is a professional? Whats the job title for someone in that field(s)?
ETA: “Entrain in the rain” is a (accidental) nice rhyme and I’m willing to bet has not appeared before in a non-scientific context, if ever.
Perfesser. Or Professor, if you prefer. Yep, she’s really got a Ph.D. studying particulate air pollution, ID’ing its sources, evaluating how it is transported and transformed by the atmosphere, and what happens to it after you inhale it. I don’t believe pollen is a particular (:D) focus of hers (she’s all about industrial sources), but as fas as being knocked out of the air by rain, the same principles apply.
Cool. Seriously, what is that called? “Environmental … something?” “Public health” something? Just trying to pigeonhole things, in best bureaucratic order. Which departments should a Ph.D. come from? Med, Metereology? WHAT’S ON HER BUSINESS CARD?!
She could be anything from a botanist to a physicist, though she’s probably an ecologist or chemist.
In the school of public health. Lots of big universities have one; for example, here’s Harvard’s.
Her degree is in environmental health sciences; for example, here’s Johns Hopkins’.
Depending on where you live, if you look at the sky toward the horizon it may be hazy before a rain and clear after. The haze comes from dust, pollen, pollution etc and the rain clears it out. In some places, about the only time the sky is really clear is after a rain. My town has a nice view of the mountains but after a dry week, they just blend into the sky and aren’t very impressive. After a rain you can almost pick out individual trees.
Fascinating. Thanks. Now I know a human taxome is in the works.