After more than 45 years of hearing about "increasing" light-pollution (LP) and reading LP related articles, I now find them infuriating and offensive. As devoted amateur astronomers, I think you need to stop posting these LP news items in a forum such as this, especially from the popular media. You're doing a disservice to yourself and to novice astronomers by linking bad science. You will not learn anything new, they oftentimes have dated information, and quite frankly they're often wrong, even those articles written from salaried astronomers.
Think about it, if LP has been increasing for that length of time, the stars wouldn't be visible at all. As I've mentioned here https://www.cloudyni...ollution-study/, polluted areas are continuously expanding and the skies seem to be more cloudy/misty to me, but LP is decreasing in many previously polluted areas.
I've added some uncalibrated pics here as examples. The topic of what to do to lower LP and curtail its expansion has to start with just the following few paragraphs.
Generally, most standard cobra-head street-lights, by virtue of both their design and their wattages, have lower levels of up-light than commercial/industrial/wallpack installations, they always had.
A good full-cutoff LED fixture installation today contributes to LP only by reflected light. Without an obstructing canopy, this can be as low as 4% of the lamp light (all grass underneath) to a high of 25% (newer concrete). Up-light percentages are typically lower with foliage canopies. Most other lights, such as private billboard lighting, flood-lighting and some lot lighting have direct up-light. Their watts are also huge, they always were.
Of course there were public installations that were more polluting, however, these were often, if not always, non-standard fixtures such as post-tops or ornamentals. Most of these bad polluters have been replaced with better LED ornamental fixtures.
The contribution to up-light from the aforementioned commercial/industrial/wallpack fixtures is still enormous. It always was. Over 25 years ago, in the early to mid sodium era, finding scandium emission lines in the spectrum of my sky-glow indicated to me that commercial areas contributed significantly to the then LP. Scandium is only added to metal-halide lamps. As I see it and I'm able to estimate, the contribution from LED commercial/industrial/wallpack installations today is over 80% of sky-glow.
There will be some LED street-lights brighter than commercial/industrial/wallpack installations, but these full-cutoff lights are few (boulevards or major collector roads) and not as widespread as all the residential street-lights. As far as we're concerned, it is far better to generalize in order to move on and fix the real problem of LP. I think it's imperative. Keep off the street-lights, they're almost perfect! Tackle the unregulated private lot, architectural and billboards and you should have a clear-cut reduction in LP.