What Ever Happened To Acid Rain?

In the 1970s, everyone was talking about the dangers of acid rain, but it seems to have fallen off the radar. What happened to acid rain?

A few weeks back, we looked at the issue of the hole in the ozone layer, an environmental concern that seemed to become suddenly unfashionable. Like cargo pants.

In today's DNews report, Trace Dominguez explores a related environmental issue -- acid rain -- that's taken a similar trajectory in recent years. Like flannel shirts, maybe. Is acid rain still something we should be worrying about?

The quick version: Yes, acid rain is still around, and yes it's still a problem. It's just a bit less of a problem, in the U.S. anyway, thanks in part to effective government regulations.

The basics: Acid rain is a pretty straightforward appellation -- it's rain that's been turned acidic by particles in the atmosphere. Rain is naturally slightly acidic, since picks up carbon dioxide in the air, producing carbonic acid. But when it starts absorbing industrial pollutants like sulfur dioxide and nitrogen oxide, the acidity becomes troublesome.

RELATED: Fukushima Accident Rained Glass Particles on Tokyo

When acid rain falls on on vegetation or soil that's already slightly acidic, or even just neutral, that's when things get bad. Living things have a hard time in acidic environments because the acid basically kills their growth enzymes. What's more, hydrogen ions in the acid rain replace nutrients in the soil like calcium and magnesium, which are vital for plant growth.

Once acid rain infiltrates soil, it flows into streams and lakes, killing marine life. Acid rain is harmful in urban environments, too, where it eats away at limestone and marble buildings. The problem has been around as far back as the Industrial Revolution, but it didn't get much until the 1970s, after it had already caused massive damage.

In the early 1990s the U.S. government passed a series of regulations that dramatically reduced sulfur dioxide emissions, reducing acid rain significantly. But it's still an issue elsewhere on the planet, particularly China and Russia, two countries with lots of factories and few environmental regulations.

In short, acid rain -- like the hole in the ozone layer -- is still an environmental issue. It's just been eclipsed by newer, scarier environmental issues.

-- Glenn McDonald

Learn More:

ScienceMag: Is Acid Rain a Thing of the Past?

EPA: Acid Rain Program

Seeker: Climate Change, Explained in One Simple Comic