Many construction companies devote a great deal of time training employees how to work safely at height, using fall protection procedures, fall arrest systems and personal protective equipment to make sure they don't injure themselves in an accidental plunge to the ground.

But gravity works on objects as well as people, so workers should also be concerned about unsecured tools and materials falling on them.

In an analysis of Bureau of Labor Statistics data, the Center for Construction Research and Training found that out of all nonfatal struck-by injuries that took place on a construction site in 2015, the majority were caused by falling building materials and tools. From 2011 to 2015, 804 construction workers died from struck-by injuries, and 52 percent of those workers were struck by an object or equipment. Solid building materials were the most common source of nonfatal struck-by injuries, accounting for about 3,500 injuries.

A falling object can do significant damage. The force of impact of a 6-pound brick falling 11 feet onto the back of a worker bent over in the kneeling position is 3,168 pounds. Replace that brick with a 50-pound piece of sheetrock dropped from 20 feet, and it’s not hard to see the potential for serious injury and even death.

There are two main scenarios in which materials and tools can fall off a building, scaffold or other work platform, and they're both preventable. Unsecured materials and tools that are blown off a roof or out of a building opening by high winds are one. Workers dropping items or otherwise causing them to go tumbling are another.

Here's how to prevent both situations. 

• Make sure materials are stacked properly, tied down and stored away from the structure's edges. The same goes for tools and equipment when they're not in use.
• Install temporary boards across any openings through which material can fall. To prevent items from falling from scaffolding, install toe boards and guardrails.
• Establish a fall zone around the building and post signs notifying workers and visitors to the site of the potential danger of falling objects.
• Erect sidewalk shelters, nets and/or screens if there is a possibility of debris falling on pedestrians passing by the worksite.
• Prohibit workers from tossing tools, waste materials or any other debris to the ground from roofs or open spaces in multistory buildings. Provide trash chutes, and make it the jobsite policy that workers carry their tools and equipment to lower floors.
• Require workers to tether their tools to an anchor point, just as they would their personal protective equipment.
• Train workers on the ground to be on the lookout for falling objects, wear hardhats and report anyone who is creating a falling-object hazard.

All it takes to prevent injuries from falling building materials and tools are some physical control measures, safety protocols and training, all of them well worth the investment.