Keywords

1 Wildland Fires: Dealing with a New Era

Fire has always played an important role in shaping ecosystems constituting an essential component of ecological balance (Bond et al., 2005). It may be a useful tool, but, if untamed, may have a severe impact on wildlife habitats, goods, and people’s lives. A “wildfire,” “forest fire,” “bushfire,” “wildland fire,” or “rural fire” (the term varies within countries) can be defined as an unplanned, uncontrolled, and unpredictable fire event that occurs in nature (Šomšák et al., 2009; CIFFC Glossary Task, and Training Working Group, 2017). The inevitability of global warming, with decreasing precipitation levels and prolonged dry seasons (Esteves et al., 2022a), has contributed to the increase in the number and severity of wildland fires (San-Miguel-Ayanz et al., 2018; Westerling et al., 2006).

As pointed out by the United Nations Intergovernmental Panel on Climate Change, there is a “greater likelihood of injury, disease, and death due to more intense heat waves and fires” (Field & Barros, 2014). Furthermore, the rising number of people working and/or living in areas close to forests increases the risk of serious damage to livelihoods or loss of human lives (Hirschberger, 2016; Radeloff et al., 2005). Thus, the more we know about wildfires’ impact (e.g., effects on human health, millions lost to the economy, destroyed habitats, air pollution, burnt houses, loss of human lives), the more we must act on, concentrating efforts on prevention and fire response for a balanced and effective forest fire management.

The management of a forest fire per se lay mostly on the intervention of firefighters. In fact, wildland firefighters are considered the backbone for resolving any forest fire occurrence (Beighley & Hyde, 2018; Moreira et al., 2009). Having well-trained and healthy firefighters is crucial for an effective fire response. The predicted increase in wildland fires requires additional efforts from the workforce, and firefighters (Withen, 2015). Although firefighter is considered one of the most dangerous occupations in the world, little is known about the health risks related to their occupational exposure.

2 Wildland Firefighters: A Brief Contextualization

The first fire brigade, called “Vigiles,” was created in 24 B.C. under the rule of Imperator Augustus and consisted of approximately 600 enslaved people and conscripts that patrolled the streets of Rome checking for crimes and fires (Butgereit et al., 2014). Later, in 60 A.D., imperator Nero allocated 7.000 freemen to fire prevention, firefighting, and building inspection activities (International Association of Fire Chiefs, 2008). After the Great Fire of London (1666) that destroyed nearly 80% of the city, insurance companies formed the first private fire brigades (Alagna, 2003). Over the centuries, firefighting systems were adjusted according to the reality of each country/people and their respective needs.

Currently, there are around 16 million firefighters in the world (91% males and 9% females) mostly volunteers, with the exception of a few countries (e.g., Italy, Spain, USA, Canada, France, Greece, Israel, and Singapore) (CTIF, 2022). Fire departments may be composed of either professional firefighters (full-time firefighters), volunteer firefighters, or both; in the United States (USA), for example, most fire departments consist of volunteer firefighters (International Association of Fire Chiefs, 2008). Generally, each fire department is responsible for a geographic area guaranteeing a fast response time (International Association of Fire Chiefs, 2008).

The risks posed by wildland firefighting are different from those related to any other type of fire suppression context (e.g., structural firefighting, such as urban). Wildland firefighters may participate in several wildfire occurrences per year and remain on the fire scene for several days/weeks (for multiple shifts with little downtime) in very hostile and unpredictable conditions (Demers et al., 2022).

Wildland firefighters have an enormous physical and psychological workload (Ruby et al., 2002); common tasks include trekking, chainsaw work, and brush removal (IARC, 2010) while carrying a considerable number of heavy equipment and tools (e.g., rakes, axes, shovels, fire hoses) (IARC, 2010; Smith et al., 2001) through remote and difficult terrains. In addition, wildland firefighters face high temperatures, high levels of noise (e.g., sirens, diesel engines) (Broyles et al., 2017), and high levels of stress, particularly when they confront life-risk situations or when they need to deal with injuries or fatalities (Smith et al., 2001). Often beginning at very young ages, most firefighters remain their entire lives in the force, being continually and repeatedly exposed to different hazards including carcinogenic air pollutants (Magnusson & Hultman, 2015). To reduce or restrict their occupational exposure, firefighters are required to use personal protective equipment (PPE) that typically comprises protective clothing, respiratory protection, a helmet, neck shroud, protective hood, gloves, goggles, and boots (Carballo-Leyenda et al., 2018).

The increasing wildfire activity worldwide requires a higher number of wildland firefighters engaged in fire suppression activities (Koopmans et al., 2022). Anticipating that the number of forest fires is expected to increase in several regions of the globe (Flannigan et al., 2006), it is essential to look for appropriate occupational health and safety measures. Even more, the evidence linking health effects to occupational exposure to wildland fire is still limited and prevention measures are seldom mentioned.

3 But… What Exposures Do Wildland Firefighters Face?

The common hazards that wildland firefighters face on the fire line can include burning over/entrapment, heat-related outcomes, injuries, mental stress, fatigue, dehydration, and smoke inhalation (Britton et al., 2013; Koopmans et al., 2022). Firefighters are highly exposed to harmful pollutants in the form of gases and particles (Smith et al., 2001). Wildfire smoke is a complex mixture containing hundreds of gases and particles such as carbon monoxide, nitrogen dioxide, mono- and polycyclic aromatic hydrocarbons (PAHs), aldehydes, and metals (Naeher et al., 2007). Plus, wildland firefighters are also exposed to other pollutants such as diesel exhaust, since they may be working near vehicles on the fire ground, in another emergency occurrence, or even at the fire station (Horn et al., 2022). Hence, it is very difficult to know all the pollutants or the mixture of pollutants that firefighters are exposed to during their activities and the extent of such exposure.

Wildland firefighters are exposed to fire smoke pollutants through different exposure pathways (Fig. 1), namely inhalation, ingestion, and dermal absorption (Ruby et al., 2002). Inhalation is the main exposure pathway for several harmful compounds that are present in smoke (Heus, 2018). The portion of pollutants inhaled is proportional to the volume of air inspired and expired, increasing with physical efforts (Stec et al., 2020). The typical respiratory protection used by wildland firefighters is a cotton bandana which offers very little protection against particulate matter (PM) due to its poor filtration efficiency, and that does not prevent the inhalation of toxic compounds (Austin, 2008; Heus, 2018; Naeher et al., 2007).

Fig. 1
Three cartoon illustrations, each of a person in uniform with a hat, labeled Inhalation, Dermal Absorption, and Ingestion, respectively.

Firefighters’ routes of exposure

Full size image

Wildland firefighters may also be exposed to fire smoke pollutants through dermal exposure (e.g., PAHS and volatile organic compounds) (Heus, 2018). Previous research has demonstrated that some pollutants may settle in the exposed skin (Rogula-Kozłowska et al., 2020) or even penetrate the firefighting protective ensemble (Barker, 2005) allowing dermal absorption of those contaminants. These exposures may be enhanced by the inadequate use of PPE or by inefficient decontamination procedures after fire suppression activities (Barker, 2005; Demers et al., 2022). In addition, exposure to high temperatures compromises the skin barrier facilitating the dermal absorption of toxic compounds (Heus, 2018; Wingfors et al., 2018). Absorption increases by 400% for every 5 °C increase in skin temperature (Stec et al., 2020).

In addition, wildland firefighters may be exposed to smoke toxicants via ingestion due to the lack of appropriate PPE (unprotected mouth) or even due to inadequate practices such as eating, drinking, and/or smoking with contaminated hands during or after firefighting activities (Heus, 2018). Moreover, contaminants that enter the upper respiratory tract may be carried via saliva into the digestive system (Stec et al., 2020).

Exposure to pollutants occurs not only during firefighting and other fire operations (e.g., prescribed burning) but also in their return to the fire station via diesel exhaust and contaminated post-fire gear and/or other equipment. The inefficient decontamination procedures of PPE or other equipment used during firefighting also favor cross-contamination in fire stations (e.g., rooms, bedrooms, offices, and garages) compromising the indoor air quality where firefighters spend long periods of their shift (Banks et al., 2021; Oliveira et al., 2017). This may occur due to a lack of knowledge of safety procedures, cultural behaviors, carelessness, or logistical conditions (Magnusson & Hultman, 2015). It should be noted that in some cases, the fire stations are located in old buildings with inefficient ventilation systems that do not prevent or mitigate the spread of pollutants within the indoor spaces (Demers et al., 2022). In this manner, firefighters face a “cocktail” of exposures via multiple routes, leading to potential exposure misclassification that may consequently underestimate firefighters’ health risks. Exposure misclassification may explain some of the inconsistencies seen in the epidemiologic literature (Koopmans et al., 2022; Sparer et al., 2017).

4 What Health Outcomes Do Wildland Firefighters Face?

Firefighters face many risks that can cause immediate or long-term consequences on their health and well-being. World Fire Statistics show that, between 2016 and 2020, an annual mean of almost 70.000 firefighters got injured, and 86 firefighters lose their lives during firefighting occurrences (CTIF, 2022). Cardiac events have been considered an important cause of death among firefighters during fire ground operations (Kales et al., 2003; Koopmans et al., 2022). In the USA, for example, sudden cardiac death (usually heart attacks) continues to be the leading cause of death among firefighters on duty (Fig. 2).

Fig. 2
A pie chart depicts the factors contributing to the U S firefighters' death while on duty. Sudden cardiac arrest reads 44% and internal trauma and crushing reads 31%.

(Adapted from Fahy et al. [Fahy & Petrillo, 2022])

US firefighters’ deaths while on duty: 2021

Full size image

These sudden cardiac events have been associated with different factors such as heat stress, exertion, dehydration, shift work, and stress (Guidotti, 2014), as well as with risk factors such as hypertension, diabetes, cholesterol, and lack of physical fitness (Kales et al., 2007). In addition, mortality rates have been largely associated with aviation-related incidents, entrapments, and vehicle collisions (Butler et al., 2017). The last is a common cause of firefighter mortality worldwide and is often related to excessive speed and the misuse of seat belts (International Association of Fire Chiefs, 2008). Besides these immediate negative health outcomes (e.g., life loss, injuries), the real impact on health is much higher, like an iceberg where we only can see the tip and not the whole bulk.

Firefighters are exposed to a wide range of harmful substances, many of them classified by the International Agency for Research on Cancer (IARC) as known (e.g., benzene, benzo[a]pyrene, formaldehyde, and PM2.5) or probable/possible (e.g., acetaldehyde, benzofuran, ethylbenzene, furan, black carbon, and styrene) human carcinogens (IARC, 2010). There are several studies worldwide indicating an increased risk of different cancers among firefighters (Jalilian et al., 2019; LeMasters et al., 2006; Pukkala et al., 2013) such as melanoma, leukemia (Tsai et al., 2015), colon, rectum, testis, thyroid (Jalilian et al., 2019), laryngeal, and hypopharyngeal (Zhao et al., 2020). In this line, in June 2022, occupational exposure as a firefighter was classified by IARC as carcinogenic to humans (Group 1) based on “sufficient” evidence for cancer (bladder and mesothelioma) in humans (Demers et al., 2022).

Not surprisingly wildland firefighting has been associated with other long-term adverse health outcomes such as respiratory (e.g., asthma, chronic obstructive pulmonary disease) (Greven, 2011) and cardiovascular outcomes (e.g., heart attacks, arrhythmias) (Andersen et al., 2017; Fahs et al., 2011; Navarro et al., 2019; Pedersen et al., 2018; Soteriades et al., 2011). The prevalence of self-reported health effects was found to be directly correlated with years of firefighting, and individuals with long careers who have higher chances to develop adverse cardiovascular outcomes (Semmens et al., 2016). According to the National Fire Protection Association, sudden death from a heart event is the most common cause of mortality among firefighters accounting for 40–50% of deaths annually (Fahy, 2005); long-term exposures to cardio-toxic compounds, such as carbon monoxide or PM from fire smoke, have been considered an important factor for vascular diseases (Du et al., 2016).

Other long-term health effects related to occupational firefighting exposure have been described (Jahnke et al., 2018). Previous studies showed that nearly a quarter of US female firefighters’ first pregnancy ended in miscarriage (higher than the 10% verified in the general US population) (Jahnke et al., 2018). In addition, the high levels of stress and traumatic situations contribute to firefighters’ vulnerability to mental health problems (Walker et al., 2016), leading to substance abuse (Carey et al., 2011), depression (Kimbrel et al., 2011), post-traumatic disorder (Chen et al., 2007), sleep disturbance (Vargas de Barros et al., 2013), and even suicidal behaviors (Boffa et al., 2017).

5 Better Health for Firefighters: Looking at the Preventive Measures

Benjamin Franklin, founder of the first volunteer fire brigade in the USA, once said “An ounce of prevention is worth a pounce of cure” (International Association of Fire Chiefs, 2008). So, the way firefighters can prevent occupational risk in their activity is the responsibility of multiple parts. Compared with some exposures encountered during firefighting, exposures at the fire station may be more easily modified through changes in systems and protocols, representing potential useful intervention targets. Fire stations should have a set of standard guidelines that incorporate safe practices and policies to protect firefighters’ safety and health. All staff should be trained in implementing such procedures and, most importantly, guarantee that firefighters are aware of the occupational risks that they face and the importance of adopting preventive measures to reduce or eliminate occupational risks.

Firefighters must know how to correctly use PPE. Equally important is guaranteeing proper maintenance through regular cleaning and inspection of PPE, repairing or replacing it when necessary. During fire suppression activities in the field, firefighters should avoid eating, drinking, or smoking with unwashed hands (Stec et al., 2020). When necessary, they must do so in a suitable environment with washed hands (e.g., water and soap or cleansing wipes) so that contaminants do not enter via ingestion (Magnusson & Hultman, 2015).

Decontamination procedures after exposure to fire pollutants are extremely important (Fig. 3), including decontamination of firefighting personnel as well as of the contaminated PPE/equipment/vehicles (Magnusson & Hultman, 2015). The decontamination procedure is a sequential set of steps that must be followed to ensure a successful decontamination process.

Fig. 3
An illustration of the decontamination cycle. The steps include cleaning equipment and vehicles, going to fire scene, transporting contaminated P P E separately from firefighters, and decontaminating firefighters and equipment personnel. A color legend reads clean, decontaminate, and contaminated.

(Adapted from Swedish Civil Contingencies Agency [Magnusson & Hultman, 2015])

The (de)contamination cycle

Full size image

The contaminated PPE and equipment should be cleaned in loco wherever possible; if not possible, contaminated PPE should be stored in proper containers/bags and transported separately from firefighters, i.e., outside the vehicle cab (Stec et al., 2020). Firefighters should change to clean and dry clothes before returning to the fire station to reduce skin exposure to contaminants (Stec et al., 2020), or else take off the undergarment as soon as possible on return to the fire station. After fire suppression activities, it is crucial to wash exposed skin areas (e.g., hands, neck, face) with soap and water. When this is not practical, firefighters may use cleansing wipes on exposed skin parts (e.g., neck and hands) to reduce the number of contaminants (e.g., PAHs) (Fent et al., 2017). However, it is important to be aware that some particles and other contaminants might remain on the skin, and as long as contaminant is present on the skin, more time is available to be absorbed (Fent et al., 2014, 2020; Keir et al., 2017). As such, showering with soap and shampoo should occur as soon as possible when returning to the fire station.

It is of utmost importance to control the spread of harmful pollutants on return to the fire station through the designation of “contamination zones” and “clean zones.” Personal decontamination should be a priority when returning to the fire station from a fire; thus having available showers in the facilities is crucial. Contaminated PPE/clothing must be cleaned/laundered after every fire event, if possible, in a special designated area “contaminated zone” of the fire station to prevent cross-contamination. During these procedures, it is important to protect areas of exposed skin (e.g., gloves) and airways (e.g., face mask) (Stec et al., 2020). Besides PPE, work tools and vehicles should also be cleaned and decontaminated regularly (Stec et al., 2020).

Construction of fire stations must be designed considering a specific layout (based on the circuit of “contaminated” and “clean” areas) and proper engineering measures to guarantee a clean airflow within spaces. The implementation of efficient ventilation systems must be a concern, particularly in the areas of the fire station where contaminated material is handled. The air quality of fire stations should be regularly monitored to guarantee safe exposure levels to air pollutants (Slezakova et al., 2022). Preventing contamination will keep firefighters and other fire station personnel protected from smoke-related contaminants.

Firefighting is a highly physically demanding activity that requires a good fitness level including aerobic fitness, anaerobic capacity, muscular strength, and endurance. The development and implementation of well-designed fitness programs that encourage physical activity and a balanced diet (e.g., water, fruits, vegetables, whole grains, and low-fat foods) are critical for the promotion of health and well-being among these individuals. In addition, regular health screening should be provided to firefighters to early detect any adverse health events. Understanding the impacts of wildland fires on firefighters’ health can help to design mitigation strategies and efficient policies to protect their health.

6 Taking Care of Firefighters’ Health in a New Era of Forest Fires—The Portuguese Reality

There are around 27.000 firefighters in Portugal (81% males and 19% females), distributed by 465 fire stations, of which 63% are volunteers and 37% are professional, with ages comprised mostly between 26 and 50 years and the majority with 12th grade of scholarly (INE 2020). A recent study found that 80% of a group of Portuguese wildland firefighters reported being exposed to smoke, gases, and particles during their activities (Esteves et al., 2022b); this finding is particularly concerning due to the long careers (average of 16 years) and the long periods of work that were described (i.e., the majority claimed to work in firefighter activities more than 10 h/day) (Esteves et al., 2022b).

Portugal is one of the European countries most prone to wildfires (Beighley & Hyde, 2018). On average 3% of Portuguese forests burn annually (Schleussner et al., 2019), corresponding to around 100.000 hectares. However, this trend has been increasing through the years (Schleussner et al., 2019); from 2008 to 2017, for example, the annual burned area varied from 18.000 hectares to 500.000 hectares (Schleussner et al., 2019).

The evident demographic shifting of the population moving from rural to urban areas, the highly fragmented and unmanaged private forested lands, the typically evergreen and drought-resistant vegetation, the high number of human-cause ignitions (negligence or intentional), and climate changes (high temperatures and decreasing precipitation levels) all contribute for the increased risk of forest fires (Beighley & Hyde, 2018; Carmo et al., 2011; Nunes et al., 2005). In December 2019, the European Council recognized that Portugal is one of the European countries most affected by climate change (European Commission, 2019). Portugal has already experienced severe heat waves, storms, and droughts (Schleussner et al., 2019). During the extreme wildfires of 2017, a record of burnt areas was registered in Portugal (500.000 hectares) and 120 human lives were taken (Turco et al., 2019), including firefighters’ lives. European Union Joint Research Center (EU-IJR) forecasts an increase in forest fire danger, particularly noticeable in the Southern countries including Portugal (Fig. 4).

Fig. 4
Two maps of Europe present the average and the projected forest fire danger in the region from 1981 to 2010 and from 2071 to 2100, respectively, along with the seasonal severity rating.

(Retrieved from EU-IJR [European Commission, 2019])

Historical and future trends of forest fire danger in Europe

Full size image

On the contrary, the number of Portuguese firefighters (professional and volunteer) has been decreasing through the years registering a drop of 33% in just a decade (Fig. 5) (Beighley & Hyde, 2018; PORDATA, 2020).

Fig. 5
A graph plots the number of Portuguese firefighters from 2006 to 2018. The curve starts at 42,208 in 2006 and ends at 26,939 in 2018.

(Adapted from PORDATA [PORDATA, 2020])

Number of Portuguese firefighters over the years

Full size image

Firefighters are crucial human tools in forest fire defense. Thus, efforts should be done to retain experienced firefighters and to attract younger people to this workforce creating attractive remuneration conditions (e.g., higher wages) and improving health and safety conditions (Beighley & Hyde, 2018). Surveillance based on monitoring programs (biological and environmental) may be a possible solution to identify potential occupational risks and their impact on firefighters’ health.

7 Conclusions and Recommendations

The implementation of a comprehensive set of preventive measures must be a priority to reduce fire occurrences and resulting damages. This is particularly relevant because, during the past decades, we have witnessed a rise in forest fires (i.e., number and severity) driven by unusually high temperatures. Government is a vital stakeholder in better structuring forest policies and providing the resources needed to prevent and deal with forest fires. Prevention efforts across different scales are essential for the success of a forest fire prevention system. Prescribed burning, fuel breaks, water reservoirs, forest access roads, meteorological warnings, and information campaigns to promote the individual responsibility of citizens are examples of some important and effective preventive measures. In parallel, it is crucial to strengthen the fire response structure so that forest fires can be rapidly detected and suppressed at early stages, preventing human and ecological loss/threats. Having healthy and well-prepared firefighters is essential to save human lives and preventing forest fires from escalating. Thus, efforts must be done to implement appropriate practices and policies to promote health and safety in this workforce.