22 Mar Effects of Weather

Effects of Weather

Weather conditions can change quickly and create serious hazards on construction sites. Although workers cannot control the weather, they can control their exposure to weather-related hazards through planning, monitoring conditions, and adjusting or stopping work when conditions become unsafe.

Wind

High winds and sudden gusts can affect employees, equipment, structures, and materials.

Wind can:

• Blow dust and debris into workers’ eyes.
• Cause unsecured materials, tools, and equipment to become airborne.
• Affect worker balance when working on roofs, scaffolds, ladders, aerial lifts, and other elevated surfaces.
• Cause inadequately braced walls, formwork, temporary structures, or materials to collapse.
• Make crane, hoisting, and material-handling operations unsafe.
• Cause suspended loads to swing or become difficult to control.

Secure loose materials and equipment before high winds develop. Follow manufacturer wind limitations for cranes, aerial lifts, scaffolds, and other equipment.

Do not continue elevated, lifting, or other weather-sensitive operations when wind conditions exceed equipment limitations or make the work unsafe.

Lightning and Thunderstorms

Lightning can occur even when little or no rain is falling. Employees working outdoors should monitor changing weather conditions and follow the company’s severe-weather procedures.

When thunderstorms threaten:

• Stop work and seek appropriate shelter when required by site procedures.
• Stay away from cranes, scaffolds, aerial lifts, towers, utility poles, and other tall structures.
• Avoid exposed rooftops, open areas, and elevated locations.
• Stay away from reinforcing steel, structural steel, fencing, and other conductive materials.
• Do not shelter beneath isolated trees.
• Stay away from water and wet areas.
• Follow site instructions regarding when outdoor work may safely resume.

A substantial enclosed building or a hard-topped vehicle generally provides better lightning protection than temporary shelters, open structures, or equipment.

Rain, Sleet, Ice, and Snow

Wet and frozen conditions can significantly increase the risk of slips, trips, and falls.

• Keep walking and working surfaces as clean and dry as practical.
• Remove accumulated snow and ice before beginning work where feasible.
• Use appropriate footwear for the conditions.
• Use handrails when climbing stairs.
• Maintain three-point contact when climbing ladders.
• Do not assume a snow-covered surface is safe. Snow may conceal holes, uneven surfaces, debris, skylights, or other hazards.
• Maintain required protection around floor and roof openings.
• Use extra caution on roofs, scaffolds, ladders, ramps, and other elevated surfaces.

Mud can also create unstable footing and increase the physical effort required to walk, lift, and carry materials.

Excavations and Trenches

Rain, melting snow, freezing and thawing, and runoff can significantly change soil conditions.

Following rainstorms or other hazard-increasing weather events:

• A competent person must inspect excavations before employees enter.
• Check for water accumulation, soil movement, cracks, sloughing, or evidence of instability.
• Inspect protective systems for movement or damage.
• Keep surface water and runoff from entering excavations when possible.
• Do not allow employees to work in excavations where accumulated water creates a hazard unless adequate precautions have been taken.

Conditions that were safe yesterday may not be safe today.

Electrical Hazards

Water and electricity are a dangerous combination.

• Keep electrical tools, cords, connections, and equipment protected from water.
• Use required GFCI protection on construction sites.
• Inspect cords and electrical equipment before use.
• Do not use damaged electrical equipment.
• Keep electrical connections out of standing water.
• Stop using electrical equipment when weather conditions make its operation unsafe.

Never enter standing water where energized electrical equipment or conductors may be present.

Heat and Sun

Hot weather and direct sunlight can cause heat stress, dehydration, heat exhaustion, and heat stroke.

Employees should:

• Drink adequate water.
• Take required rest breaks.
• Use shade or other cooling measures when appropriate.
• Gradually acclimatize to hot working conditions.
• Watch coworkers for symptoms of heat illness.
• Immediately report symptoms such as dizziness, weakness, nausea, confusion, or fainting.

Cold Weather

Cold temperatures, wind, and wet clothing can contribute to cold stress, frostbite, and hypothermia.

• Dress appropriately in layers.
• Keep clothing as dry as possible.
• Protect the hands, feet, head, and exposed skin.
• Take warming breaks when necessary.
• Replace wet clothing promptly.
• Watch coworkers for shivering, confusion, loss of coordination, numbness, or other symptoms of cold stress.

Reduced Visibility

Fog, heavy rain, snow, blowing dust, and darkness can reduce visibility and increase the risk of vehicle and equipment incidents.

• Reduce vehicle and equipment speeds.
• Use required headlights, work lights, warning lights, and high-visibility clothing.
• Maintain safe distances from moving equipment.
• Use spotters or signal persons when required.
• Stop operations when visibility becomes inadequate to perform the work safely.

Before and During Severe Weather

Supervisors and employees should monitor weather conditions and consider how changing conditions may affect planned work.

Before work begins, discuss:

• Expected weather conditions.
• Elevated work and fall hazards.
• Crane and lifting operations.
• Temporary structures and unsecured materials.
• Excavations.
• Electrical hazards.
• Emergency shelter locations.
• Heat or cold stress precautions.
• Conditions requiring work to be suspended.

Employees should know who has authority to stop work and should immediately report conditions they believe are unsafe.

Remember

Weather can turn an otherwise routine construction activity into a serious hazard. Watch changing conditions, secure materials, inspect the work area after severe weather, and stop work when conditions cannot be safely controlled. No schedule is more important than performing the job safely.