Wildfires and One Health: understanding interconnected risks

Wildfires are often viewed primarily as environmental and disaster-management challenges. But their impacts extend across ecosystems, agriculture and health.

A severe landscape fire can alter habitats, affect wildlife and livestock, damage crops and pasture, degrade air and water quality, disrupt food production and expose people and animals to direct and indirect health risks.

These connections make wildfire an important issue to consider through a One Health approach – recognizing the interdependence of the health of people, animals, plants and ecosystems.

A changing fire environment

Fire is a natural ecological process in many landscapes. Fire-adapted ecosystems depend on particular fire regimes for regeneration, nutrient cycling and biodiversity. Indigenous Peoples and other local knowledge holders have also used fire for millennia to manage land and natural resources.

The concern is therefore not fire itself, but changes in its frequency, intensity, seasonality and extent, particularly where these exceed the capacity of ecosystems and communities to adapt and recover.

Climate change, land-use change, forest degradation, agricultural practices and changes in vegetation and fuel loads can all influence fire risk and behaviour. The resulting impacts can cascade across ecological and agrifood systems.

Changing landscapes can change health risks

One important One Health dimension is the effect of fire on interactions between species.

Severe fires can cause wildlife mortality and injury, remove habitat and alter access to food, water and shelter. Surviving animals may move into new areas or concentrate around remaining resources. At the same time, livestock may be evacuated or moved to alternative grazing areas, while people may change how they use affected landscapes.

These processes can modify the interfaces between wildlife, livestock and people.

Ecological disturbance does not automatically lead to increased disease transmission. Outcomes depend on the pathogens and host species present, changes in animal abundance and behaviour, environmental conditions and the nature of contact between species. However, integrating ecological information with wildlife, livestock plant, and public-health surveillance could help identify where major landscape disturbance is creating changing patterns of exposure.

Animal, plant and ecosystem health

Wildfires can have immediate consequences for animal health and welfare. Livestock and wildlife may experience burns, smoke inhalation, heat stress, injury and dehydration. Loss of pasture, feed and water can create longer-term impacts.

Animal movements during and after wildfires can also complicate disease surveillance, identification and traceability and the provision of veterinary services. Preparedness can therefore benefit from incorporating animal-health considerations, including evacuation, feed and water provision, veterinary capacity, carcass management and surveillance.

The relationship between fire and plant health is equally complex. Appropriately managed fire can maintain ecological functions in fire-adapted landscapes. Conversely, unusually severe, frequent or poorly timed fires can damage vegetation, affect regeneration, contribute to soil degradation and alter biodiversity.

Disturbance may also change plant communities and, in some environments, create conditions favourable to invasive alien species or other biological pressures. Assessing ecosystem health, rather than simply the area burned, is therefore important for understanding impacts and planning recovery.

Air, water and soil connect the impacts

Wildfire creates pathways of exposure extending well beyond the fire itself.

Smoke contains particulate matter, gases and other pollutants and can travel considerable distances, affecting human health and exposing livestock and wildlife.

Fire can also alter soil and watershed processes. Loss of vegetation may increase runoff and erosion, while ash, sediment and other materials can enter surface waters. These changes can affect water used by communities, agriculture, livestock and wildlife.

From a One Health perspective, these are not separate environmental effects. Air, soil and water connect ecosystem disturbance with animal and human exposure.

Impacts across agrifood systems

Wildfires can create significant shocks to agrifood systems. Crops, orchards, pasture, livestock, forests, stored feed and agricultural infrastructure may be damaged or destroyed, while transport, markets, veterinary and extension services and water and electricity supplies can be disrupted.

Consequences can continue during recovery. Reduced pasture availability can alter livestock movements and stocking patterns; soil degradation can affect future production; and damage to storage, processing and cold-chain infrastructure may contribute to food loss and food-safety risks.

Understanding these interconnected effects can help recovery efforts restore not only productive assets, but also the ecological and health functions underpinning resilient agrifood systems.

Connecting integrated fire management and One Health

FAO promotes integrated fire management, a holistic approach that recognizes the ecological and socioeconomic roles of fire and its interactions with biological, environmental, cultural, social, economic and political systems. It brings together science, knowledge, technologies and practices at multiple levels, including those of Indigenous Peoples and local communities.

One Health can complement this approach by strengthening understanding of the interdependencies among human, animal, plant and ecosystem health. Connecting relevant environmental, agricultural and health data – from risk assessment and early warning through to post-fire recovery – can help identify interconnected health risks and inform measures that deliver benefits across sectors.

This complementary perspective can support collaboration among fire managers, foresters, animal and plant health specialists, public-health authorities, communities and other actors to build healthier, more resilient landscapes.