"Since reports of it surfaced in 2011, the hum has been studied by the Canadian government, the University of Western Ontario and the University of Windsor."

Do you really think that between the Canadian government and two universities, over the past seven years, that you are the first person to suggest this "obvious first step"?

I went to school and worked for a while studying spectrum management. It boggles my mind to this day that drones get in the way of fire fighting and emergency services because an obvious first step world be to allow emergency vehicles & helicopters to jam the frequencies of drones. There are plenty of other vehicles with this ability (military, secret service, etc) so it's not like the technology to solve the problem is unobtainable or non existent.

Would that be legal? Does the FCC offer such an exemption to laws prohibiting signal interference? And in what capacity? We've seen law enforcement jam cellular networks, but firefighters and EMTs? Helicopters? Should civilian helicopters also be able to jam signals? Would all this signal jamming (mostly of Wi-Fi bands) interfere with emergency services equipment or the ability of victims to call for help?

The problem is that there's an infinite number of possible frequencies. Most Hobby drones use one of the ISM "junk" bands (eg 900MHz, 2.4Ghz, etc), but it's impossible to jam ALL of the possible frequencies without wiping out communications over a wide area.

Jamming equipment is heavy, bulky, expensive, maintenance intensive, and especially power hungry. Plus due to the vagaries of signal propagation the effects are somewhat unpredictable. Installing jammers on civilian helicopters would be totally impractical.

Well, that we should know from the article.

It mentions investigations many times:

"Since reports of it surfaced in 2011, the hum has been studied by the Canadian government, the University of Western Ontario and the University of Windsor."

Those are all the links in the article, the last one (https://www.dropbox.com/s/vi8ek3hqiof81ca/UW%20Study%20Repor...) gives us

"For the duration of the project, the Hum manifested on only a handful of days, which made the identification of the source difficult. Good data representative of the Hum was measured using the stationed noise monitors. Conclusive evidence of the source was not achieved using the NSI system since the Hum was not present on those days that this equipment was deployed on the river. The conclusion of the research is that the Windsor Hum does exist and has both qualitative and quantitative characteristics that surmise the likely source of the Hum to be from the blast furnace operations on Zug Island."

So the main problem of the article is that it tries to make a mystery from something reasonably good investigated.

From what I understand, it is mostly an issue of jurisdiction. The factory is in the US, and the problem impacts people across the river in Canada.

Cross border noise pollution was likely never envisioned in any international treaties, so there is no obvious legal means to resolve the problem.

Yes there is. At least with frequency assignment. There are very strict policies that any frequency usage within 50 miles of an international border must be approved by the appropriate authority on both sides. The rules may not apply to non-communication based sound (which is an obvious failure), but it's not like there is no framework for this kind of thing, it just doesn't extend far enough.