Virtual Environmental and Humanitarian Adviser Tool – (VEHA Tool) is a tool
to easily integrate environmental considerations in humanitarian response. Field Implementation guidances are useful for the design and execution of humanitarian activities in the field.

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VEHA - Field Implementation Guidance

Essential Healthcare - Zoonotic Diseases
Infection prevention and control
Chemical control of vectors at location/environmental level

Chemical control of vectors at location/environmental level


Environmental factors causing/contributing to the needs and affecting the humanitarian activity

Chemical control of vectors at the location and environmental level:
Climatic factors affect vector population and breeding. For example, with warmer temperatures vector populations may increase because vectors that are cold-blooded thrive in a warmer environment. Also, meteorological factors affect the incidence, transmission-season duration, and spread of vector-borne diseases. In addition to this, human activity can facilitate vector breeding with water storage, mining, deforestation, and poor waste management.

However, chemical control can generate pollution and environmental degradation that may intensify environmental health risks and create harmful living conditions for the affected population and any host communities. Pollution of the water, soil, and the air is a threat to human health and wellbeing and exacerbates poverty and inequality. Pollution also affects animals and plants, thus degrading natural ecosystems and their ability to provide essential natural services and resources for society. The economic burden of pollution is usually significant, and the cost of rehabilitation of degraded environments is often prohibitive. Similarly, whilst biological control avoids chemical contamination of the environment, there may be operational limitations and undesired ecological consequences if the impact of the environmental modification is not well defined and the method poorly calibrated. Biological control methods are only effective against the immature stages of vector mosquitoes and are typically restricted to use in large concrete or glazed clay water-storage containers or wells.

Gender, age, disability and HIV/AIDS implications

Some sections of the community will be more vulnerable to vector-related diseases than others, particularly babies and infants, older people, persons with disabilities, sick people, and pregnant and breastfeeding women. Identify high-risk groups and take specific action to reduce that risk. Take care to prevent stigmatization.


Environmental impact categories

Loss of biodiversity and ecosystems
Soil pollution
Air pollution

Summary of Impacts
Potential environmental impacts

Soil, air, and water pollution due to abundant and indiscriminate use of chemicals

Impact detail
Detailed potential environmental impact information
  • Pools of wastewater are breeding grounds for mosquitoes. Contaminated water can enter watercourses, soil, and surface water, which may be used for drinking, washing, cleaning, and bathing, increasing health risks to users, including women and children. Waterborne zoonotic microorganisms present perhaps the greatest past, present, and future risks to the safety of ambient water and drinking water.
  • Eradicating disease vectors is both impractical and could result in significant damage to the environment by disrupting food chains and ecological balance.


Summary of environmental activities
  •  Plan the least environmentally damaging methods of control.
  •  Safe use of hazardous chemicals
  •  Use of the smallest quantity of chemicals necessary to limit the vector threat, as well as the total body count of vectors killed.
  •  A Safety Plan should be developed for each chemical control operation.
  •  Assessment, training, and safe use and storage of substances hazardous to health.
Detailed guidance for implementing suggested environmental activities

Assess disease vectors and plan the least environmentally damaging methods of control. Include an assessment of negative impacts on other beneficial organisms, including plants, insects, and soil biota.

The chemicals and biological agents used to control vectors are sourced from substances that have a broad and largely indiscriminate impact on the environment to ones that have limited and sometimes very targeted impacts on specific species, or stages of species development. The use of chemicals should be avoided where there are safe viable alternatives. Where chemicals are used, the most up-to-date chemicals or biological agents should be used even if older supplies are available at low or no cost and when possible, the main emphasis should be minimising the use of chemical controls. Where chemical controls have to be applied, provide guidance for their application to minimise undesirable impacts. WHO should have a lot on this.

Application methods and tools are also evolving. Even relatively recent documents may not include the most advanced tools and methods being used. Plan for safe chemical storage (procure, construct and plan for regular inspection of storage).

Lessons Learnt
Lessons from past experiences

Chemical spraying of vectors has been found to provide only short term relief whilst causing devastating impacts on local ecology. It should not be practiced.

Activity Measurement
Environmental indicators/monitoring examples
  • # of locations where disease vectors are successfully controlled without the use of chemicals that could harm non-disease flora or fauna
  • Chemical control operation has a safety plan and Staff and/or community members know how to use it.
  • Sensitisation messages on chemical vector control proper use and management are developed and promoted at household and settlement levels
Main Focus
Focus of suggested activities

Mitigation of environmental damage

Resource implications (physical assets, time, effort)
  • Time and expertise to assess disease vectors and assess alternatives to select the least environmentally damaging, including simple actions such as promoting community behaviour change.
  • Chemical control operations include a safety plan
  • IEC material to be developed – The safety plan should be publicly available and used in the training of applicators and other personnel involved in pesticide use operations.
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