Effects of Health Belief Model Interventions on Preventive Beliefs in Secondhand Smoke Exposure

The 35-item scale, scored on a five-point Likert scale from "Strongly Disagree (1)" to "Strongly Agree (5)," assesses six subdimensions: "perceived susceptibility," "perceived seriousness," "perceived benefits," "perceived barriers," "self-efficacy," and "behavioral cues." Items on "perceived susceptibility" and "perceived barriers" are reverse coded. Scores range from 35 to 175, with higher scores indicating stronger health beliefs about SHS exposure and greater beliefs in each subdimension.

Risk assessment is conducted through four questions addressing whether there is a smoker in the household, household tobacco use rules, tobacco use in enclosed areas, and the time since the last use. Responses are scored categorically: absence of risk is scored as 0, while the presence and intensity of risk are scored as 1 or more. A score of at least one indicates "risk." SHS exposure risk is scored from 0 to 10, with any score of 1 or above indicating the presence of risk. Total risk assessment scores are represented on a real risk scale of 0-10. According to expert evaluations, the content validity index (CVI) of the questions assessing participants' SHS exposure risk level is 0.86.

In adults at risk of SHS exposure, urinary cotinine analysis will be conducted using a cotinine urine test kit. The test detects cotinine in the urine, indicating SHS exposure. The strip is dipped into the urine sample for 10 seconds, and the result is read within 5 minutes. In a negative result, both the control (C) and test (T) lines will appear, while in a positive result, only the control line (C) will appear. If neither the C nor T lines are visible, or if only the T line appears, the test is invalid.

In adults, SHS exposure risk will be assessed based on the perceived level of risk. Participants' awareness of SHS exposure will be measured by their responses to the question, "How would you describe your risk of being exposed to SHS in your home?" with options such as "No risk at all," "Somewhat at risk," or "At very high risk." Additionally, participants' perceived SHS exposure risk level will be evaluated based on their numerical responses to the question, "What would your risk of SHS exposure in your home be on a scale from 0 to 10?" Each number will represent the participant's perceived (exposure risk probability) risk.

This scale was developed by Haardörfer and colleagues in 2017 to identify beliefs about third-hand smoke (THS). The scale includes 5 items related to the health effects of THS and 4 items regarding its persistence in the environment. The items are rated using a 5-point Likert scale, with the following coding: 5 = Strongly agree, 4 = Agree, 3 = Neutral, 2 = Disagree, 1 = Strongly disagree. The total score of the scale is obtained by dividing the sum of the item scores by the number of items. A score closer to 5 for each item indicates the individual believes in the health and environmental effects of THS, while a score closer to 1 indicates disbelief.