Final answer:
The sentence introduces the main point of the paragraph, identifying the health risks of outdoor smoking, including secondhand smoke and physical injury from hot ash and burning cigarettes.
Step-by-step explanation:
The function of the sentence “Evidence is growing that outdoor smoking poses health risks to non-smokers from secondhand smoke, hot ash, and burning cigarettes.” is to present the main point of the paragraph. It introduces the central argument that the essay will go on to support with additional evidence and analysis. The sentence establishes the context for the subsequent information that details the risks of secondhand smoke, the potential for physical injury from hot ash and burning cigarettes, and the rationale behind smoking bans in outdoor areas.