In 2014, there were almost 200 health awareness days, weeks or months on the 2014 U.S. Department of Health and Human Services' National Health Observances calendar.  

Since there are only 250 days in a working year, that means one day each week was not given over to some kind of health awareness effort. H.H.S. says their mission is to advocate for "evidence-based" interventions for health problems, so what evidence did they use that 200 health "awareness" campaigns were making a difference? Are they really helping anyone, or is it just less-successful attempts to get people to dump water on their own heads?

"We contend that the health awareness day has not been held to an appropriate level of scrutiny given the scale at which it has been embraced," write Jonathan Purtle, DrPH at Drexel University, and Leah Roman, MPH in the American Journal of Public Health.

To get some answers, they found 74 English-language articles in the PubMed database of scientific and medical research that referenced "awareness day(s)" in the title or abstract. Of these, only five articles were empirical studies evaluating the impact of an awareness day. All five of these articles were published since 2006 and none evaluated U.S.-based initiatives.

In the remaining articles, awareness days were mentioned in the context of editorials or commentaries publicizing an awareness day, or in the context of studies investigating concepts other than the awareness day itself--such as an awareness day being included as a study recommendation.

That's thin evidence.

"Awareness is not a bad thing," said Purtle, but "it's just that it's far from sufficient to improve population health."

The key word there is "population." The authors argue that awareness day initiatives tend to focus on changing health knowledge and behavior at the individual level. While important, this approach over-emphasizes the role of individual responsibility for promoting health more broadly.

Such strategies--teaching people to eat healthier, exercise more, get regular cancer screenings when they are at-risk--are only one piece of the picture of what makes populations healthier. Social and environmental factors have vast impacts on population health outside of individuals' choices in their day-to-day lives. And these social determinants of health are emphasized less frequently in public awareness campaigns.