Impact mitigation

Impact mitigation

Mitigating the impact of sand and dust storms before or as they occur is critical to reducing the disastrous impacts of these events. Below you will find specific sectoral guidance for and examples of impact mitigation. The practical measures described for each sector can generally be implemented at small to moderate cost.

Agriculture

For sandstorms (for example, blowing sand and moving sand dunes), impact mitigation measures can include:

• installing sand fences near agriculture areas (Al-Hemoud et al., 2019)
• planting trees or shrubs to block the movement of sand and dust (AlHemoud et al., 2019)
• deploying equipment and personnel to clear irrigation and drainage channels from sand
• changing harvesting or planting procedures and timing to avoid the impact of moving sand.

In most cases, applying source mitigation measures to reduce the movement of sand before sandstorm conditions develop are more effective than large-scale impact mitigation. However, both may need to be applied in areas where sandstorms are common and threaten large areas.

For dust storms, impact mitigation measures can include:

• wetting crops after SDS to remove dust from plants (dust on plant leaves may affect development)
• closing vents in greenhouses to prevent dust entry
• removing or protecting machinery which may be affected by dust
• reducing the use of farm equipment which could need additional maintenance if used in high-dust conditions (for example, replacement of air filters, cleaning, etc.).

The use of agricultural machinery during SDS also needs to address the impacts of SDS on safe driving and operation, for example, ensuring that workers can be seen by equipment operators.

Source: SDS Compendium chapter 13.4.2

Construction

For road construction, consideration should be given to:

• safe operation of equipment during limited visibility
• safety of workers around equipment during limited visibility
• stabilization of road terracing and roadbed development so that the winds associated with SDS do not move the material.

Note that assuring good worker visibility is a normal method to improve safety when working near equipment. The nature of SDS may require additional measures to improve worker visibility, including:

• verifying that standard visibility vests work in high-dust environments
• assessing whether goggles and dust masks impact visibility and communication
• ensuring that equipment operators located in cabs have good visibility of work areas (for example, frequent window cleaning may be required).

These measures are in addition to the health measures that may be needed when working in the hot and dry environments where SDS are common  (hydration, protection from solar radiation, etc.).

For building construction, consideration should be given to:

• erecting physical cloth or plastic sheet curtains to limit dust entry into working areas (but with adequate air conditioning when needed)
• using water sprays or misters to reduce dust load in work areas
• assessing and addressing any limitations in worker visibility or ability to be seen or heard when using goggles and dust masks
• initiating the operation of air conditioning systems early in a building’s construction, along with permanent or temporary (for example, plastic sheeting) closure of openings to the outside of buildings or within them to reduce dust entry and remove dust from work areas (these measures need to take into account fire safety).

These measures can also improve overall working conditions within buildings. In addition, for both road and building construction, source mitigation measures should be in place to limit the generation of dust during normal times and SDS events.

Source: SDS Compendium chapter 13.4.3

Education

In education facilities:

• procedures can be initiated before SDS events to reduce dust entry, by closing and sealing windows
• dust rooms can be constructed onto entry ways
• misters can be used to reduce dust load at entry ways and within large open areas
• air-conditioning systems can be operated in a way to increase filtering (though filters would need to be cleaned or replaced more frequently)
• in-room air filter units can be used as needed to reduce dust loads
• schedules for collecting and returning students using buses or other means of transport can be modified to limit their exposure to SDS outside the education facility
• special procedures should be developed to assist students and staff with health conditions that can be affected during SDS (such as asthma, impaired vision, etc.).

For education institutions with dormitories, implementing an SDS response will need to include the participation of dormitory residents. Models for engaging students in SDS response addressing transport-related issues can be taken from procedures for dealing with severe weather, such as thunderstorms and tornadoes.

These measures can be integrated into school emergency plans and, with the exception of dust rooms, be put in place when an SDS warning is received.

Knowledge about SDS, their causes and impacts, can be integrated into school curriculum. Most curriculum include natural science and increasingly include core or supplemental topics on natural hazards and disaster management into which SDS management can be integrated.

In addition, education on SDS can be undertaken by interest groups in schools, such as an environment club, community organizations, including scouts and girls’ or boys’ clubs or other such organizations.

Note that these measures apply to all levels of the education system, from preschool to university. Facilities at each level in the education system should have disaster management plans, with this being a legal requirement in many countries. These plans should include SDS early warning and impact mitigation.

Source: SDS Compendium chapter 13.4.4

Electricity

Interventions to address the impact of SDS on electricity generation, transmission and use are most likely in the following areas:

• Generation – Clean solar panels of dust and protect equipment from short- and long-term impacts of dust by improving the filtration of air taken in directly by equipment, (for example, diesel generators), and in the environment where the equipment operates (for example, generator rooms), based on forecasts and warnings.
• Transmission – Ensure that winds associated with SDS do not damage transmission lines or equipment, including measures taken before any severe weather to limit damage.
• Demand – Anticipate, based on previous SDS events, increases in electricity demand from cleaning activities after the event and during the event from increased use of air conditioners and other equipment

Source: SDS Compendium chapter 13.4.5

Health

The two immediate threats to the health sector come from:

• the movement of dust into health facilities, which impacts hygiene in the facility, the operation of equipment and testing, and the health of patients
• an increase in the caseload of individuals with health conditions that are aggravated by sand or dust conditions

Measures to reduce the impact of sand and dust on a health facility include:

• sealing windows and other openings before SDS to reduce air entry from outside
• using dust rooms at entry ways to physically isolate dust from inside air and limit it from entering though doorways
• using misters to reduce dust load at entry ways and within large open areas
• using air-conditioning systems to increase air filtering (filters would need to be cleaned or replaced more frequently)
• using in-room air filter units to reduce dust loads
• frequent use of wet mopping to remove dust from floors and other surfaces
• washing clothes exposed to sand and dust to reduce secondary entrapment, specifically inside areas that have been isolated from SDS events (such
• as rooms with sealed windows)
• modifying opening and closing schedules to limit exposure to SDS
• reducing movement into spaces where sensitive equipment is located or tests take place
• increasing the use of breathing apparatus designed to reduce air intake from ambient air, for example, using a face mask instead of a cannula.

Measures to reduce the impact of increased caseloads associated with an SDS event include:

• increasing staff based on an SDS warning
• increasing supplies of treatment drugs and equipment
• separating triage and treatment facilities from the main health facility, incorporating the aforementioned methods, such as dust rooms, misters and air conditioning
• increasing potential patients’ knowledge of ways to reduce or avoid the impacts of SDS, which can involve long-term education for SDS-vulnerable patients, as well as messaging as part of SDS warnings on how to reduce SDS impacts.

Source: SDS Compendium chapter 13.4.6

Hygiene

Living facilities (houses, apartments, care facilities, public offices and commercial markets and places of assembly) can take actions similar to those for education facilities:

• sealing windows and other openings before SDS to reduce air entry from outside
• using dust rooms at entry ways to physically isolate dust from inside air and limit it from entering though doorways
• using misters to reduce dust load at entry ways and within large open areas
• using air-conditioning systems to increase air filtering (filters would need to be cleaned or replaced more frequently)
• using in-room air filter units to reduce dust loads
• wet mopping frequently to remove dust from floors and other surfaces
• washing clothes exposed to sand and dust to reduce secondary entrapment, specifically inside areas that have been isolated from SDS events (such as rooms with sealed windows) 
• modifying opening and closing schedules to limit exposure to SDS.

For some public facilities, including shopping malls and closed markets, expanding hygiene efforts can be part of activities to provide safer places as refuge from SDS for those who may be outside when the event developed (such as a haboob). This activity would be similar to the establishment of warming spaces, such as tents, during extreme cold events, or to cooling spaces during extreme heat events. In some situations, cooling spaces will be needed at the same time as SDS events.

Source: SDS Compendium chapter 13.4.7

Livestock

SDS impacts on livestock, including cattle and other ruminants, horses, goats, sheep, ducks, geese and other animals kept in controlled situations (for example, not ranging without human intervention) include:

1. respiratory problems
2. difficulty accessing food if pastureland is covered in dust or sand
3. entering into traffic or water sources in an effort to avoid the dust or sand, or because of poor visibility.

Livestock owners or managers should develop a plan for managing SDS based on local conditions and also seek expert advice from specialists and veterinarians on animal health impacts and normal reactions to SDS by the animals of concern. Specific measures that can be considered to reduce impacts include:

• moving animals to enclosed areas before SDS events
• moving animals inside before SDS, but considering the need for adequate ventilation, water and food for the duration of the event
• providing additional food stocks if normal food supplies (for example, pasture) is covered by sand or dust
• allowing animals to move to open rangelands to reduce excitement that may be due to SDS, such as haboobs, and associated with thunder or heavy winds and rains (though care should be taken to ensure that moving animals does not put them at risk of lightning strikes)
• moving animals away from roads and waterways to avoid unplanned movements into these areas.

If animals are being kept inside a building, it is important to consider the environmental conditions (heat and humidity) within the building if a large number of animals are present and normal ventilation has been shut down because of the SDS. This could lead to hot and humid conditions which contribute to animal health issues. 

If SDS are common, developing an understanding of common local practice is important as these animals may have adapted to this hazard from  experience. 
Measures such as misters may be tested to reduce temperatures and dust loading. 
Masks are unlikely to be effective.

Source: SDS Compendium chapter 13.4.8

Manufacturing

Impact mitigation for manufacturing is likely to fall into three areas:

• reducing the entry of dust into facilities through closing and sealing windows and other openings, improving filtering and using air locks and positive pressure to block inward air movement
• reducing the dust load carried by employees and others entering facilities by requiring a change of clothes or the use of overalls
• increasing the cleaning of raw materials, parts supplied and items manufactured to reduce the presence of dust.

Although these measures are likely to be common practice during non-SDS periods, they can be expanded and upgraded through, for example, additional washing or resealing of openings, based on SDS forecasts and warnings.

Source: SDS Compendium chapter 13.4.9

Public awareness

Improving public awareness of SDS impacts can improve the uptake of warning messages (see chapter 9) and the overall adoption of impact mitigation measures.

Awareness can be raised through:

• the education system (see chapter 13.4.4)
• information campaigns before and during expected SDS periods
• site-specific SDS information, usually integrated into early warning messages (see chapter 10).

Raising public awareness about hazards, potential disasters and impact mitigation is a major task of national and subnational disaster management offices, with considerable experience and documentation on these types of efforts available. See the document Public Awareness and Public Education for Disaster Risk Reduction: Key Messages (International Federation of Red Cross and Red Crescent Societies [IFRC], 2013) for a starting point on public awareness and impact mitigation.

Source: SDS Compendium chapter 13.4.10

Sport and leisure

In most cases, outdoor sports and leisure activities would be cancelled based on SDS forecasts and warnings. Due to the short lead time and short duration for haboobs, it can be useful to set up temporary refuges (for example, in a sports hall) so that people can avoid driving during the immediate passage of a storm (see chapter 13.4.12 on transport).

In any case, the organizers of outdoor sports and leisure events during periods of possible SDS should:

• be in contact with weather and disaster management services to get timely forecast and warning information
• have plans on managing SDS events, coordinated with local authorities as needed
• have assessed and be prepared for the immediate health impacts of SDS on health-compromised individuals, including training immediate responders, stockpiling emergency supplies, planning evacuations to health facilities with local health authorities and providing warnings specifically for these individuals when SDS are expected.

Indoor events are less likely to be directly affected by SDS. However, plans should be developed to:

• seal windows and other openings before SDS to reduce air entry from outside
• open dust rooms at entry ways to physically isolate dust from inside air and to limit it from entering though doorways
• use misters to reduce dust load at entry ways and within large open areas
• use air-conditioning systems to increase air filtering (filters would need to be cleaned or replaced more frequently)
• use in-room air filter units to reduce dust loads
• wet mop frequently to remove dust from floors and other surfaces
• modify opening and closing schedules to limit exposure to SDS
• identify how to adjust participants’ road transport plans to limit driving in severe dust conditions, including driving at night when dust can have the same impact as fog on visibility.

Source: SDS Compendium chapter 13.4.11

Transport

The transport sector has received considerable attention with respect to reducing the impact of SDS. For air transport, civil aviation regulations, company operation procedures, advances in technology and improved SDS forecasting and modelling have been generally effective in reducing the risk posed by SDS in their various forms (see Baddock et al., 2013, for an example from Australia).

The greatest risk to air transport likely comes from aircraft flying into unanticipated SDS conditions (such as haboobs or the Harmattan front) and  attempting to land with limited visibility. This seems less likely to occur with scheduled air services, which are supported by dedicated weather services, and more likely with private or small commercial operations, based on experiences in the Sahel.

Specific measures to reduce the impact of SDS on aircraft (and their users) include:

• using forecasts to identify whether SDS are possible at the destination or on-route
• deciding not to fly to a destination where SDS may occur during the flight or close to the expected landing
• landing in advance of forecasted SDS or at an alternative airport where SDS conditions are severe at the intended destination
• plugging or covering vents, intakes and tubes to prevent dust from entering and sealing windows and doors, if possible
• ensuring that all intakes are clear of dust, plugs and covers before starting the aircraft
• vacuuming the inside of the aircraft after SDS to improve hygiene, limit secondary dust entrapment, reduce the need to replace air filters and reduce impacts on sensors and instruments (adapted from SKYbrary, 2019).

Conditions similar to those found in SDS can also develop for helicopters in the final stages of landing or on taking off from unimproved landing sites (for example, no pavement). These “brown-out” events are the result of the helicopter blades causing dust, sand and other small items to become airborne when the aircraft is very close to the ground. These events can cause pilot disorientation and difficulty in landing (Rash, 2006).

Ways to address this problem include:

• pilots being ready to use instrument landing procedures when brown-out is expected
• covering the landing area with a chemical treatment to prevent dust, sand and debris
• watering the area where an aircraft will land to remove conditions that allow dust and sand to be entrained in the downdraft from the aircraft (adapted from Rash, 2006).

Overall, the challenge in reducing the impact of SDS on road transport is significant. The greatest risk to this transport likely comes from haboobs or locally-blowing dust associated with agriculture (for example, ploughing fields).

Impact mitigation for road transport includes the following:

• risk assessments and the identification of specific SDS source areas and times of year (this applies to both haboobs and dust from agricultural activities, which can be time- and location-specific)
• public awareness (see chapter 13.4.10), including posting signs in possible SDS locations
• planning, including annual awareness campaigns, site mitigation measures (such as sand fences) and response to forecasts and warnings
• information collection, research and source mitigation plans to reduce long-term risk and improve the understanding of local conditions that can generate SDS
• site-specific warning messages, safety patrols and traffic controls (for example, warning lights or changes to speed limits when SDS are forecast).

Source: SDS Compendium chapter 13.4.12

Water and sanitation

SDS impacts on water quality are expected to primarily result in an increased sediment load as dust settles on water supplies. The impact is expected to be larger the greater the surface area of water covered by dust.

Reducing the impact of dust will require water filtration both at the water supply systems level and the individual (household) level for water storage containers. The need to filter SDS-contaminated water may reduce the throughput of large-scale treatment operations and increase the quantity and cost of deflocculating (pre-filtering removal of impurities) from the water. Filtering SDS-contaminated water at the household level may not be needed (for example, if the level of contamination is small) or can be done using normal water filters.

Efforts to remove dust from water supplies may be justified based on chemical or biological contaminants transported on or with dust. This risk should be assessed before SDS events.

If needed, measures for cleaning large and small water supplies can be developed, with public education on the need to clean household water supplies incorporated into the SDS public awareness process.

Some of the sanitation-related impacts of SDS are likely to be addressed through the measures described under the chapter on hygiene (chapter 13.4.7). However, based on actual SDS impacts and time and resources available, SDS-related sanitation measures will likely focus on:

• washing streets, sidewalks and public areas to remove dust
• clearing accumulated sand from drains and drainage systems (in urban areas)
• increasing sewage treatment plant operations to deal with additional greywater produced from hygiene-related activities (such as increased washing of clothes, floor cleaning, etc.).

Source: SDS Compendium chapter 13.4.13