原图下面写的说明是【The inter-annual variability of the estimated percent increases in daily mortality of PM2.5 in recent years. 】其中比较费解的是这个“of PM2.5”。我认为,论文作者说的可能是【the estimated percent increases in daily mortality attributed to PM2.5】,即估算出的由于PM2.5导致的死亡率增加百分比。