On the side of a taller building in downtown Raleigh, across from the Raleigh Times Bar, it looks as if a shimmering waterfall is plummeting down the exterior. And then, bang!, it turns yellow or red or little sparkles seem to pop out from the blue stream.
In reality, this colorful "waterfall," is an animated light projection called Particle Falls that reflects real-time air quality in downtown Raleigh.
While it's a colorful expression of art, it puts a spotlight on a serious matter. Raleigh often ranks above the national average of U.S. cities for average annual particulate pollution, which has been linked to health problems such as asthma, lung disease, cancer and adverse birth outcomes.
The exhibit aims to raise awareness about the presence and impact of particulate pollution. With the help of a nephelometer, a scientific instrument that takes in air samples and gathers data, and a computer program, the pollution data is portrayed through the animated dots and colors on the side of the building. The nephelometer hangs on a building on Wilmington Street between Gravy and Sitti, both restaurants.
Particle Falls opened last weekend and will be visible starting at dusk, daily, through April 23. The exhibit, created by artist Andrea Polli, has traveled around the country - stopping most recently in Charlotte. It's sponsored by Clean Air Carolina, NC Clean Energy Technology Center, the N.C. Department of Transportation, Novozymes, Empire Properties and Growth Energy.
Each night, at dusk, a volunteer with a T-shirt that says "AIR" on it, will stand at the corner of Hargett and Wilmington streets with more information about the display. Dusk happens around 7:45 p.m.
"There's no banner, no explanation," said Terry Lansdell, program director for Clean Air Carolina. "We want people to ask questions about what was that thing that I saw was and why was it doing that?"
If you take kids, Lansdell recommends talking with them about everything from the weather to the vehicles driving by. Those questions could include:
Did it rain? Days after it rains, the air is cleaner.
Did several buses drive by? There is a 10 or 15 second delay for the nephelometer to react, but viewers can count down after a bunch of vehicles drive by and see if the display changes.
Which way is the air blowing? If it's blowing away from the nephelometer, the fumes from a passing vehicle, for instance, might not register.
And, the fumes and particles from sources right there at that downtown Raleigh corner aren't the only thing impacting the air quality. On opening weekend, the corner was relatively quiet. The traffic was down. But, the display was going crazy. After some investigation, Lansdell said they figured out the reason.
"There was a controlled burn that was over 100 miles away that was affecting us," he said.
In Charlotte, Lansdell said, high school teachers offered extra credit to math and science students who went down to the exhibit, captured selfies and learned a bit about the impact of air quality on the air we breathe. He hopes teachers here in the Triangle do the same. (Share a photo of yourself in front of the display to @ParticleFalls on Twitter or post it on Facebook at @ParticleFallsRAL to be entered to win a free Particle Falls T-shirt).
Particle Falls is best viewed from the corners of Hargett and Wilmington streets and the deck of the Raleigh Times Bar, 14 E. Hargett St. It's a busy corner, so kids definitely need to be supervised.
And if you need more reason to head downtown at night with your kids, Particle Falls is less than a block from the new Read With Me children's book store, which will celebrate its grand opening on April 7, during First Friday in downtown Raleigh.
Particle Falls' website has more information about the display. PurpleAir.org also is tracking the air quality at the corner all day and night. As we were chatting during an interview on Thursday morning, Lansdell said the daytime monitor indicated the air quality at the corner was "unhealthy," thanks to the large number of buses and other vehicles that pass through.
"It is very scary what happens on that corner during the day versus what happens at night," he said. "It is very dynamic."