Despite efforts to reduce the levels of ozone in the US, overall reduction has been stymied by the arrival of pollution across the Pacific Ocean from China.

A new study conducted by six researchers at US and Dutch universities shows that ozone concentrations in the air over China has gone up 7 percent between 2005 and 2010, and that this increased level of  ozone  is traveling through the air all the way from China to the western United States, off-setting the significant reduction in production in ozone levels there.

The US has put into place public policy to reduce emissions which are pre-cursers to the formation of ozone, such as nitrogen oxides. On the West Coast of the US that reduction in production amounted to about 20 percent. Yet the overall air quality, especially in ozone concentrations, did not improve.

Lead researcher from the Wageningen University in the Netherlands, Willem Verstraeten, said that the worsening air pollution in Asia could be the reason the US is not seeing the kind of ozone reduction it should.

Verstraeten theorized that the “dominant westerly winds blew this air pollution straight across to the United States.  As a manner of speaking, China is exporting its air pollution to the West Coast of America.”