A scoping review of wildfire smoke risk communications: issues, gaps, and recommendations

Wildfire smoke exposure is a growing public health concern. Large wildfire events have increased [1] due to multiple factors including increased aridity and storms from climate change, and outdated fire suppression strategies. This increase has led to larger overall acreage burned and more smoke days per year [2]. Additionally, wildland urban interface (WUI) fires and homes in the WUI have increased [1, 3]. A growing body of research over the past two decades has documented that such smoke contains many pollutants that negatively impact health, including over the long-term [4]. Wildfire smoke is linked to adverse cardiovascular, respiratory, dermatologic [5‐7] and nervous system outcomes [6‐10]; has metabolic effects linked to diabetes [8]; and contains toxins that can contribute to cancer [11]. The evidence for mortality effects (respiratory and all-cause) is particularly robust [6, 10, 12‐14]. Additionally, recent research demonstrates that smoke may contribute to adverse pregnancy and birth outcomes such as low birthweight [15, 16], infant wheezing [16], and infertility [17]. Other research also points to the psychiatric consequences of wildfire smoke [18, 19].

Wildfire smoke is especially problematic for children, contributing to the development of asthma and increasing asthma exacerbations [7, 16, 20‐22]. Children are known to be especially vulnerable, both because they are growing and also because they breathe more pollutants relative to their size compared to adults [3, 23]. Recent reviews of wildfire smoke effects in children indicate a rapidly growing body of literature, with substantial evidence of respiratory, mental health, and birthweight effects in those exposed to wildfire smoke, in addition to some evidence for a variety of impacts on other conditions such as cardiac function [24‐26]. Wildfire smoke has especially impacted vulnerable at-risk populations [2], including Black, Indigenous, and People of Color (BIPOC) [1, 27, 28] as well as rural farming communities [18]. Vulnerable adult populations are more likely to have several chronic conditions, such as diabetes and cardiovascular disease, which already impact certain populations more than others, e.g., Black/African Americans have more hypertension and stroke, certain Latino populations and Native Americans have higher risks for Type 2 diabetes [29]. Vulnerable populations are at higher risk for exacerbations of those conditions, such as experiencing myocardial infarctions and/or strokes, during wildfire smoke events [6, 9, 10]. Therefore, the need for effective risk communications regarding wildfire smoke is especially critical for these vulnerable populations.

As the incidence and severity of wildfire smoke events increase and the serious health impacts become better understood, communicating effectively with the public to reduce their exposure to this environmental pollutant is a priority for public health interventions, especially for the most at-risk populations. Wildfire smoke risk communication research and communication interventions have greatly increased during the past decade [7, 30‐32]. This includes messaging primarily by publicly-funded organizations such as the US Environmental Protection Agency (EPA), US Department of Health and Human Services, Centers for Disease Control and Prevention, and state, county, and city governments in the U.S [33‐37]. as well as from community organizations in other countries [35, 38], all of which have prioritized risk communication on wildfire smoke related health effects.

There are a number of concerns with existing risk communication materials. Wildfire (“forest fire” and “bushfire” are equivalent terms used in different parts of the world) smoke exposure is an emergency event which increases the challenge of timely, effective communications. Cowie et al. found that health communications during wildfire events are a major challenge; such communications lacked reference to health risk changes based on exposure level and ages, protective actions to limit exposure over periods of time, and effective reporting and dissemination pathways [2]. Walsh et al. found that caregivers of children aged 5–12 perceived smoke as a signal of wildfire danger rather than as a health hazard itself, and none of these caregivers had access to information about wildfire smoke intended to guard children’s health [1]. An additional issue is the general lack of alignment of wildfire smoke risk communication materials with accepted health literacy principles. Health literacy principles advocate for clear communication for the public; easy-to-understand materials to help people understand health information, make informed health decisions, and take health-promoting actions [39]. However, studies show that most health communications do not adhere to health literacy principles related to readability, accessibility, and actionability—a major problem for vulnerable populations [1, 36, 40, 41]. Although the fields of risk communication and crisis communication provide a wealth of evidence-based guidance on communicating general and emergency health risks [42, 43], wildfire smoke risk communication research has emerged mostly in the past decade and best practice guidance is still limited [13, 44].

In 2021, members of our research team conducted an environmental scan [45] of existing and widely distributed wildfire smoke materials and determined that very few met the standards for good health literacy and clear communication. Given the gaps we found in our environmental scan, and the critical need for effective communication about wildfire smoke dangers and ways to reduce exposure, the need for a literature review in this area was clear. The objective of this scoping literature review is to identify: 1) relevant peer-reviewed studies about wildfire smoke risk communications, including communication resources for vulnerable, at-risk populations; 2) characteristics of effective communications, dissemination strategies, and gaps in the peer-reviewed literature; and 3) recommendations to improve wildfire smoke research and communication practices.

This scoping review [46] focused on wildfire smoke risk communications for the public. Journal articles included in this scoping literature review were peer-reviewed, indexed in PubMed or Web of Science databases, available online, and available in English or Spanish. The search was not limited by years of publication.

Journal articles excluded were those focused on wildfires rather than wildfire smoke risk communications, for example, protecting one’s property, preparing one’s household for a fire (e.g., “go bags”), or escaping from wildfires. Articles about effects of fires on health outcomes, mortality-related studies, chemical fires, post-fire interviews, and smoke plumes with satellite/remote sensing were also excluded. Gray literature, general Internet searches, and case studies were excluded.

We excluded articles if indicated articles were not within the scope of our topic, based on title review, then conducted abstract review, and finally full article review/reading/abstraction. We also scanned bibliographies of articles to identify any additional articles that should be included.

Article searches were conducted between October and December 2021 using PubMed and Web of Science databases. No limit was applied to the earliest date of publication to ensure the largest sample possible was collected. Search terms included: communication, communication strategies, education, effectiveness, environmental exposure, fire, risk communication, smoke, smoke exposure, wildfire smoke, and bushfire; various combinations of these terms were used. Bibliographies of articles were also reviewed for article inclusion.

After each search, three members of the research team (MV, SI, HB) reviewed the titles and abstracts of the outputs from the searches. After the initial title and abstract review, twenty-four articles were distributed to one of four team members (the three original team members and an additional member (LN)) for review. Throughout the period of review and abstraction, the team members met biweekly to address questions, discuss the articles, and talk through disagreements.

The abstraction process included four categories for review: risk communication approaches, research design and methods, population in the study, and results and recommendations. These four categories were selected to ensure that data collected from articles were comprehensive, concise, and consistent. The category, “risk communication approaches”, organized information about risk communications programs, materials, and strategies. The category, “research design and methods”, was included to examine the quality and robustness of the articles. The category, “population in study”, provided context around population size, location, and sampling frame. The category, “results and recommendations”, contained key article findings and takeaways. After abstraction, the team determined that twenty-one articles would be included in the scoping review. A PRISMA Diagram depicts the flow of information (articles identified, included, excluded, and reasons) through the different phases of a review (see Fig. 1) [47].

Four members of the research team (MV, SI, LN, HB) conducted the qualitative thematic analysis. Data collected from articles during the abstraction process were coded and organized into categories. If category consistency was not reached, the research team discussed the issues and reached consensus. Analysis was an iterative process with additions or rearrangement of codes and categories. Themes were communication materials and messages, communication delivery strategies, behavior change, and communications for vulnerable populations. Categories were incorporated as subsections of the four themes. Google Workspace software [48] was used for this qualitative analysis.

Articles were assessed for quality based on study design and methods (see Table 1). Within the final sample, study designs, in order of rigor were randomized controlled trial, quantitative study, mixed methods study, literature review, and qualitative study. Authors reviewed papers for qualitative indicators, such as robustness of study design, recruitment, randomization, sampling, and methods (e.g., intervention, survey, database searches, interviews) with the intent of ranking them by rigor within each category. However, due to the limited sample of available articles and methodological similarities among multiple articles in each study design category, authors made the decision to organize articles alphabetically within each of the study design categories. Table 1 describes study design and methods.

Fifteen articles examined communications materials and messaging, and they offered recommendations including discussion of messaging content and design (5 articles), approaches to communications (2), use of a mobile application (3), use of real-life video footage (1), use of mapping for information distribution (2), effectiveness of risk communications (6), and communication gaps (2).

Eight articles discussed communication delivery strategies, including traditional and digital communication strategies (7 articles), and allocation of resources within agencies specifically designated for communication and outreach measures (1 article).

Eleven articles discussed behavior change, including motivating public behavior change through community-level interventions (5 articles), increasing knowledge about wildfire smoke risk exposure among practitioners serving the public (3 articles), and examining public trust (3 articles). All eleven articles assessed behavior and behavior change (but not behavior intention) in the context of reducing wildfire smoke exposure.

Literature regarding risk communications for vulnerable populations to reduce wildfire smoke exposure was limited – only six articles were found. In general, authors found that communication resources for vulnerable populations were limited. For example, in Keegan et al., of twenty-six health protection messaging communications included in their study, only nine were relevant to vulnerable populations [55]. Specific resources relevant to pediatric populations were also found to be lacking [35].

Culturally and linguistically diverse groups, those with hearing, vision, and mobility-related disabilities, those living in high smoke-risk geographic locations, those with pre-existing chronic illnesses, those who are children or older adults, and those who are pregnant may benefit from targeted health recommendations about wildfire smoke exposure and resources on prevention/mitigation strategies [35]. Authors recommended prioritizing communications for communities that have greater exposure to smoke events [55], including actions to reduce wildfire smoke exposure instead of only updates about wildfire smoke situations [35], and providing communications to at-risk groups before the general population [44]. Mott et al. and Dodd et al. emphasized the importance of community-level initiatives for Indigenous populations in northwest Canada and in Hoopa Valley, California, to increase awareness and behavioral change [52, 57].

Postma et al. found that among young adults ages 18–26 with asthma diagnosed by healthcare providers, the Smoke Sense mobile application use was effective in increasing air quality awareness knowledge and improving asthma management [49]. Specifically, young adult participants thought that the version of Smoke Sense with Urbanova’s integrated features for mapping smoke areas, air quality advisories, spirometry graphs, weekly reminders, and peer message boards, was easy to use.

Effectiveness of risk communications: Postma et al. noted that use of the Smoke Sense mobile application and its integrated features was effective to increase knowledge about air quality and wildfire smoke and positive behaviors to manage asthma [49]. Other articles in this category did not assess effectiveness of risk communications for vulnerable populations.

We found that peer-reviewed literature about wildfire smoke risk communications is still very limited but has notably increased in the past decade as reducing exposure to wildfire smoke has become a priority public health issue. Because of the limited literature, there are gaps in all areas related to wildfire smoke communication. Encouragingly, available literature shows exploration of many important risk communication areas, including experimentation with messages, media, participatory design, community interventions, and an increasing focus on assessing effectiveness of materials and strategies in domains that include increasing knowledge, reinforcing positive behavior intention and changes, and ultimately leading to better health outcomes.

A major current gap in the literature relates to studies about communications created with and for vulnerable populations. This is an important finding of this review because at-risk, vulnerable populations are those most in need of effective communications. Some specific vulnerable populations include those who have low connectivity, are low-income, less educated, rural, and/or limited English proficient. Additional vulnerable populations include Black, Indigenous, and People of Color (BIPOC), outdoor workers, Deaf or Hard-of-Hearing people, pregnant women, children (especially those with asthma) and others with existing chronic respiratory, cardiovascular, or diabetes conditions [3, 7, 52, 62, 63]. The few articles related to vulnerable populations were helpful to point out the need to prioritize these populations, to provide more targeted health messaging and to increase community-based initiatives to develop more successful approaches to support vulnerable groups [3, 7, 28, 51]. However, specific messaging recommendations from these studies are still fairly generic. Another gap is that though some articles evaluated communications for accuracy, simplicity, and actionability, no articles explicitly examined health literacy—a central issue for high quality risk communications [33]. Finally, as in any relatively new research and practice area, there is a need for both more qualitative depth and context in the studies as well as quantitative rigor, including prospective research.

Despite the gaps in the literature, existing studies do provide rich information about known weaknesses of current wildfire smoke communications and note many recommendations to improve them. Many key issues with wildfire smoke risk communications have been identified in the existing literature. These include issues related to community-engaged design, timeliness, understandability, visual and textual elements (including mapping), selection of communication mediums, trusted messengers, actionability of recommendations, and point of contact dissemination strategies. Although many articles in this review included some assessment of effectiveness of risk communications, more work is needed in this area to examine and increase knowledge, encourage behavior intentions and change, and improve health outcomes.

Important recommendations were identified in each of the four thematic areas we focused on in this review as summarized here:

Guidance from prior studies of risk communications in other areas indicates that simple and clear communications adapted to specific cultures, languages, health literacy levels, and other factors are essential so that risk communication meets the needs of groups most at risk [64]. It is important that all wildfire smoke communications are created with attention to health literacy principles, which also would likely benefit vulnerable populations. Recommendations for future research on wildfire smoke communication include evaluating the differential effectiveness of various kinds of messages and media, studying communications tailored for the diverse US populations, and co-developing communications using health literacy principles with vulnerable populations.

This is a scoping review of the peer-reviewed literature about risk communications related to wildfire smoke exposure. Scoping reviews are helpful prior to planning a study, to identify gaps in research, to tailor a study or design interventions, and to include multiple types of studies, not limited to randomized trials or quantitative studies. This can be especially important when there are few articles for unique populations, as we found in this review. There was no publication date limit selected to maximize collection of relevant articles. This scoping review also included articles from authors located in various countries affected by wildfire smoke.

There was a limited number of articles from any one country, limiting the ability to make any country-specific conclusions. Available articles in languages other than English and Spanish were not included, given our a priori inclusion criteria. No studies were found in Spanish language which may indicate a critical gap in the evaluation of wildfire communications for Spanish-speaking populations. The biggest limitation was the limited literature in this area to date, which impacted interpreting the issues and recommendations in this review. However, we did note that there was often convergence among authors about important issues cited and recommendations for improved wildfire smoke risk communications.