110 S. Ito et al.: Radioprotection 2025, 60( 1), 109 – 119
McClure et al., 2016; McInnes and Haglund, 2011). While there are no studies evaluating text difficulty for nuclear disaster materials, an evaluation study of patient education materials reported that adult and pediatric radiation therapy patient education materials exceeded recommended reading levels( Al Balushi et al., 2020; Delaney et al., 2021; Hansberry et al., 2014; Prabhu et al., 2016; Yi et al., 2018). It has been reported that people with lower health literacy and literacy skills are more likely to have poorer overall health( Berkman et al., 2011; Svendsen et al., 2020). Additionally, a survey conducted in Fukushima Prefecture after the Fukushima Daiichi Nuclear Power Plant accident by Tokyo Electric Power Company reported that people with lower health literacy were more anxious about radiation( Kuroda et al., 2018; Nakayama et al., 2019). Furthermore, health literacy among the Japanese is lower than in other countries( Nakayama et al., 2015), and in a post-nuclear accident survey, Fukushima residents( Moriyama et al., 2020) were less health literate than the general Japanese population( Goto et al., 2019; Ishikawa et al., 2016). To improve understanding, it is important to assess the difficulty of radiation-related disaster preparedness materials to match the average literacy level of the local population who will be the readers.
To encourage protective actions by the public during a disaster, the information provided must be easy to understand, easy to act upon, and easy to read. The National Workgroup on Cancer and Health( Cotugna et al., 2005), the American Medical Association( Weiss, 2003), and the Centers for Disease Control and Prevention( CDC)( Centers for Disease Control and Prevention( U. S.) et al., 2009) recommend that patient information materials be readable at a 6th to 8th grade level or lower. However, many online medical materials are more difficult than this standard( Hutchinson et al., 2016) and the readability of nuclear emergency preparedness materials is not clear. The purpose of this study is to clarify the current state of nuclear disaster preparedness manuals by evaluating their ease of understandability, actionability, readability, and credibility.
2 Methods
2.1 Website selection
In this study, we conducted a systematic quantitative content analysis of online materials. From November 27 to December 8, 2023, the survey used Google as the search engine, as in previous epidemiological web page reviews( Alwani et al., 2021; Ito and Furukawa, 2024; Shneyderman et al., 2022). Selection criteria were as follows: the web pages were in Japanese, related to nuclear disaster prevention, and aimed at the general public. Videos; academic papers; reports; advertisements; newspaper articles; pages for medical, educational, and public agency personnel; broken links; inappropriate content; sites requiring subscriptions or fees; and complex disaster prevention materials such as those regarding earthquakes or typhoons were excluded. In cases where only evacuation maps and contact information differed between municipalities and other materials consisted of the same content, only one representative case was extracted. This study was not subject to ethical review because it did not involve any human subjects or interventions.
The search keywords were“( radiation OR radioactive material OR nuclear) AND( disaster prevention OR disaster) AND( pamphlet OR handbook OR leaflet OR flyer OR bookmark)”, and all 219 web pages found through this search were reviewed. Of these, the Reconstruction Agency( 35 web pages) and the Nuclear Human Resource Development Network( 57 web pages) provided a list of web pages related to radiation disaster prevention, so these web pages were also reviewed. An exhaustive manual search was also conducted because more than 10 years had passed since the Great East Japan Earthquake and many materials were difficult to find by keyword search alone.
2.2 Evaluators
In this study, one epidemiologist studying the nuclear accident reviewed the materials on the websites and independently evaluated all but those whose content was clearly inappropriate. Next, an internist who did not specialize in radiation or nuclear disasters evaluated 30 randomly selected websites from among all the websites using the PEMAT-P. The PEMAT-P is an index intended to be evaluated by health care providers and health professionals who provide medical information. This independent evaluation by a person who specialized in radiation and nuclear hazards and a nonspecialist was performed to avoid the possibility of information bias in the evaluation of the material. In cases of disagreement, consensus was reached through discussion.
2.3 Understandability and actionability
The understandability and actionability of the contents of each website were evaluated using the Japanese version of the PEMAT-P( Furukawa et al., 2022; Shoemaker et al., 2014). The PEMAT-P Japanese version is a 23-item evaluation tool designed to assess the understandability of health and medical information for patients and consumers, and evaluates items such as“ content”,“ word choice and style”,“ use of numbers”,“ organization,”“ layout and design,” and“ use of visual aids.” The questionnaire items are listed in Table 4. Evaluators were required to respond to each item by selecting either“ Disagree = 0” or“ Agree = 1”. These scores ranged from 0 % to 100 %, with higher scores indicating higher levels of perceived comprehensibility and ease of actionability. The cutoff value was set at 70 % for both scores.
2.4 Readability
In this study, to quantitatively evaluate the readability of Japanese text on web pages, we used jReadability, a tool that analyzes elements such as grammar, sentence structure, word complexity, and sentence length, with the aim of making the text easier to understand( Lee, 2016; Lee et al., 2023). The index calculates readability based on the average length of a sentence, word difficulty, percentage of grammatical parts of speech, and type of characters per sentence. Scores range from 0.5 to 6.4, with higher scores indicating that the sentences are relatively easy to read: 0.5 – 1.4, very difficult to read; 1.5 – 2.4, difficult to read; 2.5 – 3.4, somewhat difficult to read; 3.5 – 4.4, neutral; 4.5 – 5.4, easy to read; and 5.5 – 6.4, very easy to read).