A recent study by the University of Leeds and the Southern University of Science and Technology in Shenzhen divulged PM2.5 had only a small reduction across China and it was not lowered at all in Northeast China. The PM2.5 reduction of 11% across China was disappointing in comparison to the reduction 27% of NO2 across China.  

Recently the National Parks Conservation Association (NPCA) published a report stating that 85% of parks deal with unhealthy air due to ozone. While ozone is thought of typically resulting from vehicle and industrial emissions, park plants also emit compounds that react with NOx gasses to make ozone.