A 21% reduction in ozone-forming pollutants in the Western US between 2005 and 2010 was partially wiped out by polluted air from China blowing across the Pacific Ocean, according to a study by NASA’s Jet Propulsion Laboratory and scientists from The Netherlands, published on August 10, 2015, in the online journal Nature Geoscience.
Ozone is composed of nitrogen oxide gasses (NOx) and volatile organic compounds (VOC), by-products of burning coal and gasoline, such as car exhaust gasses and factory smoke. Also, particulates from tobacco smoke, aerosol sprays, and paint fumes contribute to the toxic mix. The study measured ozone readings between 10,000 and 30,000 ft (3 to 9km) above ground level. Over time, about half those pollutants will sink to ground level. According to the Environmental Protection Agency (EPA), ground level ozone causes shortness of breath, eye irritation, and sore throats, and long exposure can prematurely age lungs and cause lung disease. Ozone is a major component of smog.
China’s power plants and factories burn more than 4 billion tons of coal a year, and more coal-burning plants are under construction and scheduled to go online in the years ahead. Most of China’s coal-burning plants do not use pollution mitigation technology, so most of the coal-burning ozone pours out the smokestacks directly into the lower atmosphere. The pollutants rise with the heat into the upper atmosphere (troposphere) and the stratosphere. The jet stream at higher altitudes and prevailing winds at lower altitudes carry the polluted air westward across Japan, across the Pacific Ocean, and into the skies of the Western US.
While China has been active in developing wind and solar energy projects, renewables are a very small percentage of China’s total energy production. Coal furnishes 70% of China’s energy and will continue to be their major source of power for the foreseeable future.
China is not alone in producing pollutants that cross borders. The US still burns about a billion tons of coal a year, and while many American plants are equipped with scrubbers and other mitigating systems, pollution still escapes into the atmosphere and travels with the wind. US pollution reaches the EU, and EU pollution blows on toward Mongolia and into China.
The answer lies in renewable energy such as wind and solar gradually replacing coal-burning plants throughout the world, including China. When that day finally arrives, we will all breathe easier.