Effects of ambient PM1 air pollution on daily emergency hospital visits in China: an epidemiological study oleh Gongbo Chen, MPH, Shanshan Li, PhD, Yongming Zhang, MD, Wenyi Zhang, PhD, Daowei Li, MD, Xuemei Wei, MD, Yong He, MD, Michelle L Bell, PhD, Gail Williams, PhD, Guy B Marks, PhD, Bin Jalaludin, PhD, Michael J Abramson, PhD, Dr Yuming Guo, PhD