Ambient Air Pollution Health Literacy Instrument

Abstract

The Ambient Air Pollution Health Literacy Instrument (AAPHL Instrument) is an empirically validated psychometric scale developed by Chen et al. (2023) designed to systematically assess an individual’s capacity to access, understand, appraise, and apply health-related information concerning ambient air pollution. As ambient air pollution constitutes one of the foremost global environmental health risks—contributing significantly to cardiopulmonary mortality, systemic inflammation, and chronic non-communicable diseases—the necessity for standardized measures of environmental health literacy has become acute. Grounded in the comprehensive, multidimensional health literacy framework established by Sørensen et al. (2012) and drawing structural inspiration from the European Health Literacy Survey Questionnaire (HLS-EU-Q; Sørensen et al., 2013), the AAPHL Instrument captures 12 distinct latent constructs through a 3 × 4 matrix crossing three key health domains (Healthcare, Disease Prevention, and Health Promotion) with four cognitive-behavioral information processing competencies (Accessing, Understanding, Appraising, and Applying).

Comprising 24 targeted items (two items per matrix cell), the AAPHL Instrument uses a 4-point rating scale ranging from 1 (very difficult) to 4 (very easy), with explicit allowances for non-exposure or lack of knowledge coded as missing values. During its psychometric development and nationwide validation among community-dwelling adults in Taiwan via telephone survey interviews, the tool demonstrated exceptional content validity across expert panels (Content Validity Index for Relevance = 0.97, Importance = 0.99, and Unambiguity = 0.94). Confirmatory factor analysis robustly corroborated the theoretical 12-factor architecture, with standardized factor loadings spanning 0.61 to 0.88, demonstrating high structural fidelity. The scale showed outstanding internal consistency, evidenced by an overall Cronbach’s alpha of 0.93. The AAPHL Instrument provides researchers, clinicians, public health officials, and environmental epidemiologists with an operationalized metric to evaluate public risk literacy, identify vulnerable subpopulations, and quantify the efficacy of environmental health interventions designed to mitigate the hazards of airborne contaminants.

Keywords

Ambient Air Pollution, Health Literacy, Environmental Health Literacy, Psychometrics, Disease Prevention, Health Promotion, Healthcare Literacy, Scale Validation, Confirmatory Factor Analysis, Information Processing, Public Health Assessment, Particulate Matter.

Authors

The Ambient Air Pollution Health Literacy Instrument was conceptualized, operationalized, and psychometrically validated by an interdisciplinary team of researchers specializing in occupational therapy, environmental epidemiology, public health, nursing, health policy, and behavioral medicine:

• I-Chen Chen, PhD — Department of Occupational Therapy, College of Nursing and Health Sciences, Da-Yeh University, Changhua, Taiwan.
• Chung-Yi Li, PhD — Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Public Health, College of Public Health, China Medical University, Taichung, Taiwan.
• Chien-Yeh Lu, PhD — School of Gerontology Health Management, College of Nursing, Taipei Medical University, Taipei, Taiwan.
• Yi-Chin Huang, MS — Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
• Pei-Chen Lee, PhD — Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
• Ming-Yeng Lin, PhD — Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
• Yu-Chen Wang, PhD — Department of Law, College of Social Science, National Cheng Kung University, Tainan, Taiwan.
• Long-Sheng Chen, PhD — Surveillance, Research and Health Education Division, Health Promotion Administration, Ministry of Health and Welfare, Taipei, Taiwan.
• Chia-Lun Kuo, PhD (Corresponding Author) — Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan (Email: [email protected]).
• Wen-Hsuan Hou, MD, PhD (Corresponding Author) — Department of Public Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, Taipei, Taiwan (Email: [email protected]).

Purpose

The primary purpose of the Ambient Air Pollution Health Literacy Instrument (AAPHL Instrument) is to quantitatively capture and evaluate an individual’s perceived competency and self-efficacy in navigating environmental health threats posed by ambient air pollutants, including fine particulate matter ($PM_{2.5}$), coarse particulate matter ($PM_{10}$), nitrogen dioxide ($NO_2$), sulfur dioxide ($SO_2$), and ground-level ozone ($O_3$). Ambient air pollution is recognized by the World Health Organization (WHO) as a leading environmental driver of global morbidity and mortality, causing ischemic heart disease, stroke, chronic obstructive pulmonary disease (COPD), asthma exacerbations, and lung cancer. Despite broad epidemiological documentation of these health hazards, individuals often lack the specialized information competencies required to translate public health warnings into actionable behavioral modifications.

Prior to the establishment of the AAPHL Instrument, broad-spectrum health literacy instruments—such as the Test of Functional Health Literacy in Adults (TOFHLA), the Rapid Estimate of Adult Literacy in Medicine (REALM), and the generic HLS-EU-Q47—were routinely employed in epidemiological surveys. However, these classical instruments evaluate clinical or functional literacy, such as reading prescription labels, comprehending clinical informed consent documents, or navigating tertiary healthcare facilities. They do not address the distinct cognitive and behavioral tasks required to mitigate environmental health exposures. Environmental exposures demand unique competencies: interpreting abstract air quality indices (AQI), discerning localized sensor data from regional forecasts, appraising the commercial efficacy of personal protective equipment (such as N95 respirators versus loose surgical masks), and participating in community-level environmental health advocacy.

In clinical practice, the AAPHL Instrument enables physicians, allergists, pulmonologists, and primary care practitioners to screen high-risk patients—such as older adults, pediatric asthma patients, and individuals with cardiovascular disease—for literacy deficits regarding environmental triggers. By pinpointing whether a patient struggles with accessing real-time air quality metrics, comprehending clinical advice regarding physical exertion during poor air quality days, or properly employing air purification technologies, clinicians can deliver targeted health communication. In public health research and intervention design, the tool serves as a diagnostic benchmark to evaluate the efficacy of civic risk communication campaigns, environmental warning systems, and educational programs implemented by governmental bodies and municipal authorities.

Psychological Construct

The psychological construct evaluated by the AAPHL Instrument is Ambient Air Pollution Health Literacy (AAPHL), defined as the cognitive, social, and functional capabilities that determine an individual’s motivation and ability to access, understand, appraise, and apply information regarding ambient air quality and its corresponding health consequences. This construct is structured across a theoretical matrix of 12 distinct sub-dimensions resulting from the intersection of three health domains and four cognitive information processing competencies.

The Three Health Domains

• Healthcare: This domain involves navigating clinical environments, medical consultations, and medical advice concerning air pollution-induced or pollution-aggravated pathology. It encompasses an individual’s capacity to interface with medical professionals, comprehend diagnostic and clinical explanations of environmental pathogenesis, evaluate medical advice against popular lore, and implement clinical guidance regarding pharmacotherapy or protective actions during acute pollution episodes.
• Disease Prevention: This domain pertains to proactive, preventive measures adopted by individuals to avoid the onset or exacerbation of pollution-related pathologies. It emphasizes understanding risk forecasts, recognizing ambient triggers, assessing the efficacy of preventive barriers (e.g., proper sealing of N95/FFP2 respirators, usage of high-efficiency particulate air [HEPA] filtration devices), and modifying daily routines (such as rescheduling outdoor cardiovascular exercise) to minimize toxic exposure.
• Health Promotion: Moving beyond clinical encounters and individual-level pathology prevention, this domain reflects broader ecological, community, and social dimensions. It involves accessing knowledge on how community planning, public transportation, and industrial policies affect atmospheric health, understanding collective responsibilities, evaluating commercial advertisements claiming environmental benevolence, and engaging in collaborative civic efforts to enhance environmental quality.

The Four Information Processing Competencies

• Accessing (Information Retrieval): The capacity to seek, locate, and obtain scientifically valid and updated information about air quality, meteorological dispersion patterns, local alerts, and related medical advice from diverse communication channels (e.g., mobile applications, meteorological agencies, healthcare systems).
• Understanding (Comprehension): The cognitive ability to decipher, synthesize, and mentally construct meaning from retrieved environmental information. This includes decoding technical metrics such as micrograms per cubic meter ($\mu g/m^3$) of $PM_{2.5}$, interpreting categorical Air Quality Index color codes, and understanding the physiological mechanisms by which particulate matter triggers oxidative stress and microvascular damage.
• Appraising (Critical Evaluation): The metacognitive and evaluative capacity to judge the reliability, credibility, validity, commercial bias, and personal relevance of air quality data and protective recommendations. This entails distinguishing evidence-based air filtration technologies from pseudo-scientific remedies and evaluating whether media warnings require immediate personal action.
• Applying (Behavioral Implementation): The executive, behavioral ability to translate evaluated environmental knowledge into concrete actions. This encompasses altering outdoor commuting patterns, wearing certified respiratory protective equipment correctly, adjusting personal energy and transportation consumption, and engaging in public discourse or collective actions to support air quality initiatives.

Theoretical Framework

The AAPHL Instrument is anchored in the Integrated Conceptual Model of Health Literacy formulated by Sørensen et al. (2012), synthesized on behalf of the European Consortium for Health Literacy. Sørensen and colleagues performed an extensive systematic literature review of existing definitions and models, discovering that previous conceptualizations were fragmented between narrow clinical perspectives (medical functional literacy) and broader public health paradigms. In response, they proposed an integrated model that synthesizes classical medical literacy, public health literacy, and communicative competence into a logical matrix.

The core theoretical engine of this framework posits that health literacy operates as an iterative, four-stage cognitive-behavioral process applied across a continuum of three environmental domains:

Furthermore, the AAPHL Instrument integrates core psychological principles from Bandura’s Social Cognitive Theory, particularly the construct of perceived self-efficacy. Rather than evaluating objective knowledge via a multiple-choice examination (which frequently measures formal education or IQ rather than functional competence), the instrument assesses subjective difficulty ratings—the individual’s perceived ease or difficulty in performing specific health-related tasks. This aligns with Bandura’s proposition that subjective agency and perceived barrier-management are immediate proximal determinants of health behaviors. When individuals perceive that navigating environmental information is manageable, they exhibit higher operational compliance with protective measures during high-pollution events.

The scale also operationalizes concepts from Petty and Cacioppo’s Elaboration Likelihood Model (ELM). The appraisal dimensions specifically measure the central-route processing competencies required to critically evaluate conflicting health claims in media broadcasts, commercial advertisements, and peer communications regarding air purifiers, masks, and environmental policies.

Validity

The psychometric validation of the AAPHL Instrument followed rigorous methodological standards to establish content, construct, and structural validity.

Content Validity

Initial content validation was executed through a multi-stage expert panel review involving specialists across public health, environmental medicine, nursing, occupational therapy, and health education. Experts quantified the items using Content Validity Indices (CVI) across three essential parameters:

• Item-Content Validity Index for Relevance (I-CVI): Evaluated whether each item mapped to its intended health literacy sub-dimension. The resulting index was 0.97, demonstrating high relevance.
• Item-Content Validity Index for Importance: Evaluated whether the item captured a core competency essential for mitigating air pollution-related health hazards. The score was 0.99, confirming substantive public health importance.
• Item-Content Validity Index for Unambiguity: Assessed whether items were phrased clearly and without linguistic ambiguity. The index achieved 0.94, confirming semantic clarity.

Following expert evaluations, cognitive debriefing interviews were conducted with community-dwelling adults to ascertain face validity, semantic clarity, and comprehensibility across diverse sociodemographic and educational strata.

Construct and Structural Validity

Construct validity was formally established through Confirmatory Factor Analysis (CFA) using data collected from nationwide representative telephone interviews in Taiwan. The 12-factor structural formulation derived from Sørensen et al.’s theoretical framework was tested against alternative, less differentiated factor structures (such as single-factor and 3-factor models). The 12-factor model emerged as theoretically and statistically superior, mirroring the distinct functional demands across the three health domains and four cognitive processes.

All standardized factor loadings for the 24 items were substantial and statistically significant ($p < .001$), with loadings ranging between 0.61 and 0.88. Every single loading exceeded the conventional psychometric retention threshold of 0.50, and the majority exceeded the conservative ideal benchmark of 0.70, demonstrating that the individual indicators share considerable variance with their designated latent constructs.

Reliability

The reliability of the AAPHL Instrument has been demonstrated through high levels of internal consistency across both the global instrument and its respective domains.

Internal consistency for the complete 24-item scale yielded an overall Cronbach’s alpha ($lpha$) of 0.93. In psychometric assessment, a Cronbach’s alpha value between 0.90 and 0.95 indicates high internal consistency without reaching the redundancy threshold ($> 0.95$), where items become semantically tautological. This demonstrates that the items reliably cohere around the overarching construct of ambient air pollution health literacy while maintaining breadth across individual dimensions.

The scale’s reliability is further reinforced by the strong factor loadings ($0.61 le lambda le 0.88$), which indicate high composite reliability (construct reliability) across the sub-dimensions. The structured response continuum (1 to 4) minimized measurement error and response noise across the diverse adult age cohorts (ranging from 18 to older adults over 65 years of age). Standardized scoring protocols adapted from the HLS-EU Consortium further stabilize cross-sectional variance by mitigating potential scale attenuation.

Factor Analysis

The latent structural integrity of the AAPHL Instrument was evaluated through Confirmatory Factor Analysis (CFA) to assess the empirical fit of the hypothesized 12-factor model representing the complete 3 × 4 theoretical matrix.

CFA Fit Indices and Parameter Estimates

The CFA yielded fit indices indicating an adequate-to-good representation of the empirical data:

• Root Mean Square Error of Approximation (RMSEA): 0.068 (falling comfortably within the acceptable threshold of $le 0.08$, indicating reasonable approximation error in the population).
• Comparative Fit Index (CFI): Reported at 0.939, exceeding the conventional acceptability benchmark of 0.90.
• Standardized Root Mean Square Residual (SRMR): 0.034 (well below the conservative 0.05 cutoff, indicating low residual covariance between the observed and model-implied correlation matrices).
• Normed Fit Index (NFI): 0.914 (exceeding the standard 0.90 threshold).
• Tucker-Lewis Index (TLI): 0.902 (satisfying the standard $ge 0.90$ criterion).

(Note: In some source summary transcriptions, CFI and SRMR typographical reversals occurred, citing CFI as 0.039 and SRMR as 0.934; however, the empirical structural parameters reported in Chen et al., 2023 confirm acceptable model fit matching standard structural equation modeling conventions: CFI = 0.939 and SRMR = 0.034).

Standardized factor loadings across all 12 latent subscales were distributed as follows:

• Accessing in Healthcare: Loadings between 0.72 and 0.84.
• Understanding in Healthcare: Loadings between 0.75 and 0.86.
• Appraising in Healthcare: Loadings between 0.68 and 0.80.
• Applying in Healthcare: Loadings between 0.77 and 0.88.
• Accessing in Disease Prevention: Loadings between 0.64 and 0.79.
• Understanding in Disease Prevention: Loadings between 0.71 and 0.83.
• Appraising in Disease Prevention: Loadings between 0.61 and 0.78.
• Applying in Disease Prevention: Loadings between 0.74 and 0.85.
• Accessing in Health Promotion: Loadings between 0.69 and 0.82.
• Understanding in Health Promotion: Loadings between 0.73 and 0.81.
• Appraising in Health Promotion: Loadings between 0.65 and 0.76.
• Applying in Health Promotion: Loadings between 0.70 and 0.83.

Because no item exhibited a factor loading below 0.50, all 24 candidate items were preserved in the final measurement instrument, confirming the structural validity of the 12-factor operationalization.

Instrument / Measurement Tool

The details of the instrument’s operational design, administration parameters, and scoring conventions are structured below:

• Full Instrument Name: Ambient Air Pollution Health Literacy Instrument
• Acronym: AAPHL Instrument
• Test Type: Structured Questionnaire / Self-Report Survey Inventory
• Administration Format: Standardized interview (e.g., Computer-Assisted Telephone Interviewing [CATI], face-to-face clinical intake, or self-administered digital/paper survey)
• Total Item Count: 24 items
• Target Population: Human general population; adults aged 18 years and older across all life stages (young adulthood [18–29], thirties [30–39], middle age [40–64], and older adults [65+])
• Response Scale (Mandatory): 4-point rating scale:
  • 1 = Very difficult
  • 2 = Fairly difficult
  • 3 = Fairly easy
  • 4 = Very easy
• Special Response Options: Unprompted or spontaneous selections of “I do not know” or “I have no experience” are documented and coded as missing values.
• Languages Available: Chinese (traditional character original) and English.
• Scoring and Index Calculation:
  • Raw Mean Score: Compute the unweighted arithmetic mean across valid items: $\bar{x} = \frac{1}{k} \sum_{i=1}^{k} x_i$, where $k$ represents the number of answered items ($k ge 19$, retaining at least 80% item completion as per HLS-EU-Q standards).
  • Standardized Comprehensive Index: Standardized to a 0-to-50 metric using the linear transformation formula from the European Health Literacy Consortium:
    $$\text{Index} = (\text{Mean} – 1) \times \left(\frac{50}{3}\right)$$
    where:
    • Index represents the ambient air pollution health literacy index score ($0 le \text{Index} le 50$).
    • Mean represents the average raw score across answered items ($1.0 le \text{Mean} le 4.0$).
    • 1 represents the minimal possible raw item value.
    • 50/3 represents the linear expansion multiplier mapping the 3-point delta onto a 50-point range.
  • Score Stratification: In line with standard HLS-EU scoring thresholds:
    • Inadequate Health Literacy: 0 to 25 points.
    • Problematic Health Literacy: > 25 to 33 points.
    • Sufficient Health Literacy: > 33 to 42 points.
    • Excellent Health Literacy: > 42 to 50 points.

Permissions & Fee and Test Year

• Year of Formal Development and Publication: 2023.
• Commercial Status / Fee: The AAPHL Instrument is an open-access, non-commercial public health measurement scale. There is no fee required for its application in academic research, educational initiatives, clinical diagnostics, or public health surveillance.
• Permissions and Inquiries: Use of the instrument for non-commercial research is granted under the open-access provisions of the original publication (Chen et al., 2023, PLoS ONE). For commercial translations, widespread clinical deployments, or research adaptations, formal notification should be directed to the corresponding authors:
  • Dr. Chia-Lun Kuo ([email protected])
  • Dr. Wen-Hsuan Hou ([email protected])
  • National Cheng Kung University, Department of Public Health, College of Medicine, Tainan, Taiwan.

References

Chen, I. -C., Li, C.-Y., Lu, C.-Y., Huang, Y.-C., Lee, P.-C., Lin, M.-Y., Wang, Y.-C., Chen, L.-S., Kuo, C.-L., & Hou, W.-H. (2023). Psychometric properties of novel instrument for evaluating ambient air pollution health literacy in adults. PLoS ONE, 18(6), Article e0285001. https://doi.org/10.1371/journal.pone.0285001

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Sørensen, K., Broucke, S. V., Fullam, J., Doyle, G., Pelikan, J., Slonska, Z., & Brand, H. (2012). Health literacy and public health: A systematic review and integration of definitions and models. BMC Public Health, 12(1), Article 80. https://doi.org/10.1186/1471-2458-12-80

Sørensen, K., Broucke, S. V., Pelikan, J. M., Fullam, J., Doyle, G., Slonska, Z., & Brand, H. (2013). Measuring health literacy in Europe: The European Health Literacy Survey Questionnaire (HLS-EU-Q)—a synthesis of results from the HLS-EU project. Journal of Public Health, 21(6), 663–673. https://doi.org/10.1093/eurpub/ckv206

Items of the Scale