But I'll do my best to share some of the steps toward this conclusion:

#1. There is a body of molecular research showing dust mite allergens directly damage the immune system, most importantly once you inhale their fecal pods, they cause epithelial permeability in the lungs. (this study is a good overview of several ways it directly damages the immune system, all of which are totally unrelated to type 1 hypersensitivity, btw: https://www.jacionline.org/article/S0091-6749(18)30848-0/ful...)

#2. There are challenge studies that show dust mites directly causing eczema symptoms after inhalation, which shows that dust mite allergens can act on areas other than the respiratory system, probably by entering the blood stream. Of course there are also challenge studies for asthma. (here's a paper arguing for causal role in asthma https://www.atsjournals.org/doi/full/10.1164/rccm.200811-175...)

#3. All of the major allergic diseases(asthma, eczema, rhinitis, and although it is not as well studies, I believe IBS) have epithelial damage and increased allergy as a core feature of the disease. #1 and #2 are good evidence that dust mites play a causal role in these diseases

#4. From asthma and epithelial permeability in the lungs you can get to worse outcomes from flu and covid etc, from rhinitis you can get to worse sleep and worse mental health etc and reach a large number of health outcomes.

#5. It's true that people with allergy suffer worse from all these problems, but so much damage has already been done before you even get to Type 1 hypersensitivity, but that's another story.

So basically, dust mites directly damage your immune system in the lungs, skin, nose, eyes, guts(and maybe more?), create a sustained immune response, and leads to a multitude of other bad health outcomes.

And since low vitamin D is associated with dust mite sensitization((https://www.worldallergyorganizationjournal.org/article/S193...) , it's also associated with all those other bad health outcomes that are actually caused by dust mites.

People have a mental model that vitamins are at the root level of causality, and therefore don't consider that vitamin D could also be caused by dust mite exposure.

IgE levels are inversely associated with vitamin D: https://www.nature.com/articles/s41598-020-77968-1

But supplementing vitamin D doesn't lower IgE: https://publications.aap.org/pediatrics/article/150/Suppleme...

And of course high IgE is directly caused by exposure to dust mites if you're sensitized.

I don't know the specific mechanism by which they cause low vitamin d, but two possibilities are that #1: the high and sustained immune response your body runs from constant dust mite exposure consumes vitamin D and acts like a leaky bucket. #2: dust mites somehow disrupt vitamin d production in the skin(e.g. there was one study showing https://www.jacionline.org/article/S0091-6749(13)01768-5/ful...)

pastybara.com

But if you can maintain low humidity for a longer periods, the dust mite populations in your home will go down and frequent washing will be less important.

Regarding whether or not your health issues are caused by dust mites, if you have any of the allergic disease, or if you have a tested dust mite allergy, it is likely they are causing problems. Disease severity is also associated with dust mite exposure.

Basically, the worse you have allergies, the more likely it's dust mites.

It's an almost certainty you home has dust mites and their allergens, unless you live in a very dry climate.

My advice is to create conditions in your house in which dust mites cannot thrive, which is relatively easy to verify with hygrometers. Over time, this will lead to lead to lower allergen levels, particularly if you are proactive about removing the ones that are currently there.

One important thing people are missing about dust mite allergy is the many ways in which they directly damage your immune system and body, outside of the usual frame of "allergies" which is based on type 2 hypersensitivity.

This article is a great introduction to the harms they cause at the molecular level: https://www.jacionline.org/article/S0091-6749(18)30848-0/ful...

I also wrote a free guide to help people get dust mites out of their house:

https://dustmiteguide.com

I've done this a few times and overall it went better than working with a stranger-founder.

ALTHOUGH - You should understand that, independent from the various forms of risk the business faces, and also independent from the financial risk and uncertainty you face through your agreements with the startup:

1. The social fabric of startups are highly unstable for the first few years.

2. The beliefs the participants have about the world, the other people in the organization, what to do, and so on is also highly unstable.

Your relationship is a minor player relative to the other(sometimes chaotic) forces affecting the organization, however generally it works in your favor.

Also, the normal rules for navigating a startup are still apply. Of those, the most important is selecting the right startup to join.