At the end of last year, Beijing issued its most severe air pollution warning for only the second time in history. Dangerously high levels of smog, the polluted mixture of smoke and fog, persisted in the city for over five days.
Beijing and neighboring regions were forced to enter a state known as ‘Red Alert.’ Schools were canceled, cars were kept off the roads, and many factories were asked to pause production.
Since the incident, China has received a lot of pressure from European countries and the U.S. to improve the country’s air quality.
So why does the U.S. care about China’s air quality?
The answer, according to Dr. Uma Shankar, a researcher of intercontinental air transportation at UNC-Chapel Hill, is really quite simple.
“It is true that domestic sources of emissions are the primary cause of air pollution in the United States,” says Shankar. “But like many countries, the U.S. is a heavy importer and exporter of air pollution.”
In Chapel Hill, Shankar works on creating models for ozone and other air particles on the regional and global scale. She also studies the benefits of global greenhouse gas reduction.
Shankar says that air pollution moves across regional and international borders at an incredibly fast rate. Such transport of air pollution greatly impacts the U.S.’s ability to maintain and regulate air quality standards domestically.
“There is no such thing as our air or their air,” says Shankar. “There is only the air and what other countries do impacts us very much.”
Shankar says that many large-scale experiments have shown that pollution originating thousands of miles away can be observed in the air that people breathe due to atmospheric behavior.
She says air is typically carried in the south-west direction toward the earth’s upper atmosphere and then lowered back down through the push of air from above. This process is sometimes referred to as the Warm Conveyor Belt.
Where does the pollution come from? China?
Shankar says there are no primary culprits of polluted air exported into the United States.
“Yes, some countries emit considerably more greenhouse gas than others,” says Shankar. “But air is constantly moving from one region to another, from one country to another, and from one continent to another.”
She says that it would be very difficult to identify where exactly our pollution is coming from.
“Ozone tracer studies have shown transport from North America to Northern Europe,” says Shankar. “There is also empirical evidence of intercontinental transport of air pollution from China to the Midwest in the United States.”
She believes that the sheer complexity and unpredictability of the atmosphere will prevent researchers from ever knowing exactly where pollution in a certain region originated from.
“The air that we are breathing right now comes from not just our near neighbors like Canada and Mexico,” says Shankar. “It can come from countries in Africa, Europe, and Asia as well.”
What exactly is polluted air and what does it do?
Air with any combination of pollutants such as ozone, dust, soot, and sulfate can be classified as polluted air. When these pollutants are found abundantly enough, they can pose a serious threat to public health and the environment.
“The human health impacts of ozone and particulate matter such as dust, soot and sulfate are well established now,” says Shankar. “When inhaled, they can lead to lung cancer and other respiratory diseases.”
Dr. Jared Bowden, another researcher of air pollution at UNC Chapel Hill, says that particulate matter, especially soot is the most dangerous.
Soot, also commonly known as black carbon, comes from combustion inside diesel-powered vehicles and the burning of organic matter. Bowden says it is also one of the most easily transported types of particulate matter.
Yuqiang Zhang, a Ph.D. student at UNC Chapel Hill agrees and adds that all polluted air is harmful.
“Some may be harmful to human health while others may be harmful to the environment,” says Zhang. “It’s very scary. The incident in China last year has shown the world just how terrifying air pollution can be.”
Some pollutants like carbon dioxide have long term environmental impacts where as others such as ozone have immediate human health impacts.
What can be done?
“This is a billion dollar question!” says Shankar.
Many differing opinions exist about the best course of action for tackling air pollution. However, experts seem to agree that stricter regulation across the world will be absolutely essential.
Both Shankar and Bowden agree that international cooperative efforts are needed to insure good global air quality. They also agree that international policy changes must be implemented intercontinentally first and then expanded.
“Targeting only a few countries will allow us to see what works,” says Shankar. “It will be easier to expand it once we prove its effectiveness on the small scale.”
Zhang believes that countries need to realize that improvement needs to take place globally and not simply within their nation.
“The reduction of air pollutants in one country can and will bring benefits for the air pollution in other countries,” says Zhang. “Simply changing policy within one specific country will not be enough in the long run.”
When asked about the specifics behind potential international policy, Shankar said existing agreements to cap carbon emissions could be extended to pollutants such as ozone and particulate matter.