Please, before you get upset and emotional- try to analyze the facts. This "study" is based on "estimates". It is sponsored by an Anti-Tobacco group. The WHO is also notorious for publishing poor scholarship/research. I defy you to find one published case-study of a person's death (let alone the death of a child) that has evidentiary link to another person smoking near them.
I happen to know of one from the 70's (the root cause of a lot of hysteria) but doubt I could find it, anymore. It was the case of aging spinster sisters who lived together for 40+ years. One smoked and one did not. They did not leave their apartment more than a couple of hours a day. The smoker sister went through 3 packs of unfiltered cigs a day. Eventually, the second sister also developed lung cancer. At the age of 60 something. By the way, many people who don't smoke or work in mineshafts develop lung cancer every day. In this case, there seemed to be a causal link. From this one exceptional case and entire industry of fear mongering and social transformation was born.
This article is nothing but propaganda. Don't buy the hype. Use your own brain.