我想要做的图如附件所示

下面是是我在网上找的代码

cb2.pm10 <- crossbasis(chicagoNMMAPS$pm10, lag=7,

                     argvar=list(fun="lin",cen=10), arglag=list(df=4))

model <- glm(death ~  cb2.pm10 + cb2.temp + ns(doy, 4) + ns(time,3) + dow,

              family=quasipoisson(), chicagoNMMAPS)

pred.pm10 <- crosspred(cb2.pm10, model, cumul=T,at=10:20)

a <- (pred.pm10$matRRfit[10,]-1)*49.68

b <- (pred.pm10$matRRlow[10,]-1)*49.68

c <- (pred.pm10$cumRRhigh[10,]-1)*49.68

dlnm <- data.frame(a,b,c)

请问蓝色部分是什么意思啊？求老师同学指教

#绘图

plot(1:8,dlnm$a,xlab="",ylab="death(95%CI)",xaxt="n",bty="l",

     ylim = c(min(dlnm$b),max(dlnm$c)),pch=19)

arrows(1:8,dlnm$b,1:8,dlnm$c,angle = 90,length=0.02,code = 3)

lab <- c("lag0","lag1","lag2","lag3","lag4","lag5","lag6","lag7")

axis(side = 1,at=1:8,labels = lab)

abline(h=0,lty=2,col=2)