How immoral is smoking around children?

I see it all the time: people holding a child while smoking, walking with a child while smoking, smoking with their kid in the car. It gives me flashbacks to when I was a kid and my mom or grandpa would smoke around me, and I just feel so bad for those kids. It was difficult to breathe. Their hot ashes would fall off and flutter onto my skin, leaving tiny burns. Do smokers acutally think that cracking a window means all the smoke is going out that window?

Not shockingly, my asthma all but went away within a couple years of moving out of my parents' house. There's really no scientific question anymore as to whether or not smoking around children is hazardous for them.

So the question here is: just how immoral is it to force children to breathe second-hand smoke?