Learn English – Should we use an article (a, the) before Business (noun)

The short answer is no. The adjective does not change the syntax.

The long answer is that nouns can convert class from mass to count or vice versa. There's an old joke that if you have a really powerful machine that turns anything into powder ("a universal grinder") then you can make any noun from a count noun into a mass noun -- "that's a lot of man on the floor."

To go the other way, you don't even really need a machine -- whenever you are comparing multiple instances of a mass noun, you convert it to a count noun: "the sands of Texas are whiter than the sands of Florida."

As a result, you will find many instances of nouns that are usually mass nouns being converted to count nouns.

For your examples, I find "a soothing music" hard to parse, "a deadly pollution" makes sense (we are imagining several instances of pollution, this one a deadly one), "a hot tea" is fine (with food items that are mass nouns, we convert them a lot when we are ordering them at a restaurant, e.g. I'll have a tea), "a hard work" sounds terrible to me when describing the mass noun "work" (which means labor) but there is also a count noun "work" (a creation arising from a lot of labor, like the works of Beethoven) and here it makes sense to describe one as "hard."

But the point is that the adjective has nothing to do with it. It's just that the mass noun has been converted to count, and there happens to be an adjective.

When you want to make a general statement about something, and the noun is countable, you don't use the article:

Horses have hooves.

The above means "All horses".

If you use the article, you're not referring to all horses, but to specific horses:

The horses have been training in a simulated high altitude environment with low oxygen, to improve their lung capacity for the big race.

If you say:

The horses have hooves.

someone might reply, "Of course they do! All horses have hooves".