Given a travel related situation, and given a specific question about the situation, summarize the question into a title

[EX Q]: I am moving to Poland this summer and would like to take my two HEPA air filters with me (it really helps with my breathing, especially when the air is so polluted in the region). However, they are rated for 120V at 60Hz while the only reasonably priced transformers change the voltage to ~120V, 50Hz. I am not sure what else to do because I have have severe breathing issues and even my skin reacts to something there (hard to figure out what this is). A 50 to 60Hz transformer would be more expensive than ordering a new filter from the UK (I can't seem to find these filters anywhere in Europe except on amazon.co.uk), which I would like to avoid doing.

Will a ~50W motor (120V, 60Hz) accept 120V, 50Hz power without issue, especially since this is in a fan, which ought to keep it cool?

[EX A]: Can a 60Hz fan motor run on 50Hz?

[EX Q]: I am applying to the French embassy for a one-month Schengen visa. For proof of sufficient means, I have my bank statement (with slightly over $7000) and monthly pay slips (of about $1500). The document requirements say that I need to submit 3 years of IT returns, but I've only been working for 2 years and haven't filed IT returns even for those years. Can this be a cause for possible rejection of my application?

[EX A]: Are the tax return document mandatory for a Schengen visa?

[EX Q]: I've bought an airline ticket (with SK) that I'm entitled to refund per their Conditions of Carriage because of a schedule change. They've agreed to refund me, but say that they will only refund me to the card I used to book the flight. This card has been cancelled, and I will not be able to get the money from my bank if it is "returned" to this card.

Are airlines entitled to only repay you to the credit card you booked with when this is not mentioned in their CoC? If not, who do you contact to enforce your agreement with them (short of small claims court)?

[EX A]:
Refund airline ticket to different credit card