In the case of responsibly and professionally blended “100% natural” herbal smoking mixtures, yes. Overall, the herbal smoking blend industry has a good track record for safety (other than the negative health effects known to be associated with smoking) when the products are used as directed by healthy adults. There are very few herbs that do not come with some warning for pregnant or nursing women and people with health problems. These people should consult their doctor before smoking any substance.
Safer than Tobacco?
It depends on how you look at it. The fact of the matter is that, although many people find herbal blends enjoyable and relaxing, they have (in most cases) not been shown to be habit-forming. So, in that respect, they are safer because it is less likely the act of smoking herbs will become habit-forming.
As far as smoking herbs being safer to smoke than tobacco, we simply do not have enough scientific evidence to be able to answer that. We have seen research that shows particular herbs and blends produce less tar than tobacco when burned and have fewer harmful compounds. We do know that, when smoked, herbs produce tar and carbon monoxide, which are known to have negative side effects. This leads to reason that the habitual smoking of any substance is likely to be unhealthy.