Then the only grounded location that I can think of is the ground pin of an electric outlet.
Do you have a somewhat technically minded friend? Making a cable like the one I suggested is literally as simple as screwing in a handful of screws. So if you know anyone who’d be willing to make it, it’s not much effort at all.
You could also get a DIY power cable (the type where you screw the plug to the leads yourself). There you only connect the ground contact and not the live and neutral contacts. Now strip the end of the ground wire and place it where ever you want to be able to discharge yourself.
Alternatively, you can do about the same by just connecting a wire to any unpainted part of your radiators.
Watch out with the type of humidifier though. Standing water and parts that never dry (e.g. inside hoses in the humidifier) are perfect breeding grounds for bacteria. And “cool mist” type humidifiers use ultrasonic frequencies to atomize all that crap that builds up in your humidifier and spread it into nice little droplets, which are perfect for getting germs really deep into your lungs.
If you tend to get respiratory infections quite often, your humidifier might be to blame.
Swimming. Here, kids have to take mandatory swimming courses at school. I have quite a few eastern european friends, and they all tell me, that swimming is something that people learn if they want to and if they can afford it, but it’s not learly an universal skill in their countries.
Most people who drown here are actually immigrants, who see everyone swimming and think that it can’t be that hard…
Humidity yes, bacteria and other germs, especially germs that can live in water are a massive no-go. Germs like Pseudomonas aeruginosa would give him a permanent lung infection and many strains of it are resistant to pretty much all antibiotics.
For people with his condition, a Pseudomonas infection is usually the point where stuff like sports or even walking up stairs permanently ends.
So raising humidity isn’t bad, but the means to do so are a killer, literally.
Btw, thanks for the downvote. I’m sure you know much more about the illness of my child, an illness that I haven’t even named here, than I do, who has to make sure that kid survives. Seriously, that kind of behaviour triggers me so much. That happens so often, that people who haven’t even heard of that illness before know everything better. It seriously makes me angry.
That kid spent ~5% of his life in hospital, getting IV antibiotics due to his condition. He takes ~30 doses of medicine a day, just to keep him alive. But people who wouldn’t even know how to spell the condition think they know better.
Pro tip: If you aren’t affected by the specific illness in question / aren’t taking care of someone who is, keep your armchair medical knowledge to yourself.