The article doesn't cover this, but it's worth pointing out why the study asks this particular question. With a single-payer system the Nordic countries want to know what the ROI is if we sent letters out to everyone above a certain age offering a free colonoscopy. The study is well-designed to answer that question.
The study does a poor job of helping an individual asking a similar but different question: Is it worthwhile for me to pay out of pocket for a colonoscopy?
The latter question is very important in a system that isn't single-payer and so this has sparked a lot of debate in e.g the US.
The article says it will "diffuse away" which implies they just let it escape the device. It'll then move through the tissue / fluids, reach the blood and eventually be breathed out. I did a quick google search to see if we already had some level of hydrogen gas in our body.
It seems that bacteria in the human gut already produce some hydrogen gas and that breath contains measurable levels of it[0]. This was news to me, but means that dumping a tiny amount of H2 into the body is probably fine.
One of the four parties in the ruling coalition has rural voters as their main constituency. This weirdness might be the result of them negotiating to keep the cost of driving a tractor around low. I'm not sure what they are doing on the local roads, but I see them a lot when driving outside the city.
In his book Flow, Mihaly Csikszentmihalyi dives a bit deeper into what sort of "problems" we should choose for yourself if we want a happy life. The gist of it is that we should pick activities that we can loose ourselves in. Everyone's experienced this, where they work on something, look at the watch, and a surprising amount of time has passed. A few examples of good "problems": learning an instrument, coding something or learning a sport.
I highly recommend reading the book, as he goes into the key features that get us into the pleasant flow state, so you know what variables to tweak if you can't get there.
In practice people (e.g. exchanges, that know who you are after KYC) still opt to wait a little because if something does go wrong it's a hassle to actually get paid. For the same reason, we are likely to check some of the bills in a large cash payment for authenticity, even though we have effective recourse through the police and the judicial system.
The block time is 2 minutes. You can choose to wait for 0 blocks or 100. The longer you wait the better the security of your transaction, because there's more PoW behind it. All crypto work like this. You also get more security behind your tx by waiting in a PoS system.
If you're buying a coffee the vendor is likely to let you leave the shop after no confirmations (as soon as their node hears about the transaction) but if you're buying a car the same is unlikely to be true.
The study does a poor job of helping an individual asking a similar but different question: Is it worthwhile for me to pay out of pocket for a colonoscopy?
The latter question is very important in a system that isn't single-payer and so this has sparked a lot of debate in e.g the US.