A cloud of pollution three times the size of California blanketed China last month that was so dangerous residents were warned to stay indoors and avoid outdoor activities. Many locals reported visibility so poor that buildings down the street were obscured. Images of Beijing covered with murky brown air were a startling reminder of how rising pollution from factories and automobiles can spoil the air in that industrializing nation.
In cleaner cities around the globe, those images of Beijing -- like the one at left -- served as an effective tool for understanding what it's like to live and breathe Beijing-quality air. Marketplace's China correspondent Rob Schmitz has been covering China's bad air for years (today on Marketplace he reports on the economic boom of bad air) and notes that on bad days the visibility is, at most, 50 feet to 100 feet in front of you.
The U.S. Embassy in Beijing, which tracks the tiny toxic particles that cause the sky to turn dark, known as PM2.5 particles, reported levels last month that were off the charts -- topping out at 755 on the air quality index (AQI), a system of measurement that officially maxes out at 500.
Simulating smog We wondered what other cities around the globe might look like under these pollution conditions, so we built a simple simulator to illustrate. Using side-by-side photos of Beijing to calibrate our not-so-scientific "obscurity filter," we applied the tool to photos of some major cities around the globe. Play around with the sliders below to see what these cities might look like with a Beijing-level air quality index.
Visibility an indicator The science backs this up, according to Sam Atwood, a spokesman for the South Coast Air Quality Management District, one of 35 districts in California that monitors air quality to comply with state and federal requirements. He explained that the PM2.5 particulates that pollute the air directly correlate with visibility.
"Essentially, these very tiny particles absorb and scatter light coming from the sun," Atwood said.
Another pollutant, nitrogen oxide, is known for creating the whiskey-brown haze. And moisture also reduces visibility and enhances particulates, making the air look more polluted than it actually is, Atwood added.
"We focus on PM2.5 because that’s the size of particle that the federal government now sets its health standard by," he added. "The very tiniest of them can even pass through the lung tissue into the blood stream. That’s why PM2.5 has been associated with a wide-range of health effects, including thousands of premature deaths every year in California."
Here's a look at how some other cities might look like with the haze we see in Beijing and Shanghai. Want to see what your city might look like under a toxic cloud of pollution? Tweet us a photo @MarketplaceAPM.
Photo Credits: Baltimore courtesy Daniel Ewald via Twitter; San Francisco by Justin Sullivan/Getty Images; New York by Saul Loeb/AFP/Getty Images; Beijing by Ed Jones/AFP/Getty Images; Paris by Eric Piermont/AFP/Getty Images; Toronto via Twitter.