here are some guidelines for adjusting the furniture in your work area to accommodate your physical size and shape.
1 an adjustable chair that provides firm, comfortable support is best. adjust the height of the chair so your thighs are horizontal and your feet flat on the floor. the back of the chair should support your lower back (lumbar region). follow the manufacturer's instructions for adjusting the backrest to fit your body properly.
2 when you use the computer keyboard, your shoulders should be relaxed. your upper arm and forearm should form an approximate right angle, with your wrist and hand in roughly a straight line. make sure the armrests of your chair don’t interfere with your positioning. you may have to raise your chair so your forearms and hands are at the proper angle to the keyboard. if this makes it impossible to rest your feet flat on the floor, you can use a footrest with adjustable height and tilt to make up for any gap between the floor and your feet. or try lowering the desktop to eliminate the need for a footrest. another option is to use a desk with a keyboard tray that is lower than the regular work surface.
3 position the mouse at the same height as your keyboard. allow adequate space to use the mouse comfortably to the immediate right or left.
4 position the monitor directly in front of you with the keyboard directly in line with the monitor. the best distance from your eyes to the screen is up to you, although most people seem to prefer 18 to 28 inches (45 to 70 cm).
5 position the monitor to minimize glare and reflections on the screen from overhead lights and windows. tilt the monitor to the best angle for viewing, helping to reduce or eliminate glare from lighting sources you can’t move.
6 adjust the brightness of the screen to ensure the best image quality and viewing comfort.
for more health and safety information about your computer equipment, open mac help from the help menu when you’re in the finder. you can also see the following (english only) world wide web site:
www.apple.com/about/ergonomics