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Comment by hastily3114 | Hacker News Reader

Interesting. I noticed that many people have hay fever in Japan, but I always just assumed it was genetic or something. I wonder if living there for a long time will make you more sensitive to pollen

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As someone who has suffered from hay fever for my entire life, and also lived in many different locations, almost every move came with a 2-3 year reprieve from my symptoms while my body "discovered" the fun new local allergens.

Same.

I'd been wondering why my allergies go nuts every time I visit Japan, but never really suffered in other Asian countries. Cool to know now.

Upside is I discovered the trick of just taking fexofenadine every single day which had the side effect of solving my chronic sinus infections.

My quality of life is notably better from daily fexofenadine vs what I think was low-level allergies that I developed in my 20s to pets, dust, etc

It’s known that repeated exposure to allergens can cause allergic symptoms in people previously without them. For example https://en.wikipedia.org/wiki/Bird_fancier%27s_lung https://en.wikipedia.org/wiki/Farmer%27s_lung

I actually seemed to grow out of hay fever when I was in my early 20s. Perhaps coincidentally this is also around the time I developed an allergy to cannabis from overuse. Wonder if they’re related somehow.

Poison ivy/oak sensitivity varies with lifetime exposure. On rare occasions, it is inverse: careful exposure can sometimes lead to resistance. More commonly: you get more sensitive over your lifetime, and some "once immune" people end up catastrophically changing due to incautious exposure.

It's complicated.

it's a bit of a balance. based on this advice, there was a long time recommendation to avoid giving young children peanuts. however, this advice was rescinded after it turned out to increase peanut allergies.

Lots of people I know who moved here as adults have developed pollen allergies over the years. Some after a 2 or 3 years, some after 10.

Yes. I developed hay fever after living here in Japan for a couple years. Was fine the first few years, though it was amusing to watch "yellow clouds of pollen" being blown from the trees with random gusts of wind. Now it's not so amusing. My car windows are dusted with a new layer of "light yellow" every couple days now (in season).

It's super easy to be allergic to cedar pollen because it is such a fine pollen. I developed a cedar pollen allergy within a couple years of moving from somewhere with no cedar to a heavily forested area with cedar. No other allergies to anything, I don't think I'm particularly prone. I tried doing the allergy shots for it for a while but it didn't seem to do much. What works is staying inside with the house sealed up and air filters running, or just getting the hell out of town for a month+.

Airconditioning 24/7 everywhere makes people weak is my theory.

AC are the bane for allergic people. It dries the air and flares the nostrils

I would assume it has more to do with less exposition to hay/pollen in urban areas, for instance in years in Beijing I've had hardly allergies since it is not exactly green, though I went to parks, but here in Prague right now with everything blooming it's nuts.

Actually now that I think about it never head really problems with allergies even in Southeast Asia, though I was in very green areas, maybe humidity helps as well?

I think the humidity has to play a role in that. Very dry air is not good for the nose even without allergies. This year the spring is very dry and also quite cold in Central Europe which makes things worse.

In Japan, however, it's almost always very humid. Today, for example, it's over 70% relative (when the sky was still clear and mostly blue, now it's raining so it's much worse). And, as said in that article, there's a lot of allergy in Japan. My wife (native) has a little bit of it, and I myself also reacted for a while, but given time it seems to have left me (as I mentioned elsewhere I grew up on a farm with exposure to everything and I never had an allergy before).

There's one guy I know who lives more or less in the middle of a forest with both Sugi and Hinoki, and he's suffering a lot. But he still likes it much better there than in the huge city where he grew up. I noticed that among the locals in that place (just a bunch of houses, not even a village) I didn't see anyone else with that kind of allergy.

> In Japan, however, it's almost always very humid.

Yeah I realised that's a little bit of an issue in my theory. Of course if it's very humid I would also expect that most buildings have aircon that's keeping the humidity down and can contribute to the allergies.

Buildings, as in large buildings, maybe. Homes don't use that much aircon. We actually never do, except if we have guests, and in any case it's never used the way I experienced so often in the US - that it's actually cold (and very uncomfortable). When used in Japanese homes it's used sparingly. There's also typically a "dehumidify"-only setting, but that's mostly a losing battle, what with the house being surrounded by humid air (and until very recently even new homes were far from airtight), so mostly you just live with it.

I got hayfever on my 3rd year of living here, and it seems like quite a common pattern among immigrants I've noticed. I have hayfever back in the UK too, but I guess I didn't have a Cedar allergy - so it took time to develop.

Sample size of 1, for a couple years in Japan had no issue but then hit like a truck.

I have allergies to ragweed and didn't have spring allergies before that. Now back in the US and have spring allergies as well.

I have been living in Japan for almost 8 years now, and I didn't have any allergy ever until a month ago when all of sudden it hit me like a hammer. Good god was it painful...

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