Extrapolate to the evidence on second-hand smoke? No, but do consider the source.
I didn't recognize the names, but the disclaimer at the bottom made me curious: "I have collaborated with Dr. Enstrom on two scientific papers and can directly attest to the honesty and integrity of his research." Then I found the reason to mention second-hand smoke - lots of reasons to be skeptical: www.no-smoke.org/document.php?id=333
Concluding: "Enstrom and Kabat?s substantial methodological flaws, combined with the tobacco industry?s funding of the study, and other studies supported by the tobacco industry, can help you to inoculate others against this misinformation."