HP Jornada 680 HP Jornada 680/680e Handheld PC User's Guide - Page 179

Ergonomics ï 173 tion-free as possible, with background noise below 58 dBA. Where possible, relative air humidity should be in the range of 40 to 60 percent. Recommended room temperature is 19 to 23 ºC (66 to 73 ºF). If possible, adjust the temperature to a comfortable level. The workplace should be well ventilated. Pay attention to your posture; relax your shoulders and keep your wrists straight. This is easier when your keyboard can be positioned right under your hands while bending your elbows at 90º. Pull your chin in to look down, and try to lean back in the chair. The backrest should support you in the hollow of your back. Reducing eye strain Have your eyes checked on a regular basis and ensure your eyeglass prescription is suitable for working on a computer screen. Look away from the screen from time to time. Focus on distant objects briefly. Blinking periodically helps to lubricate the eyes. Preventing muscle stiffness Avoid holding your muscles tense for long periods of time. Keep your fingers and body relaxed. Changing tasks frequently helps prevent muscle stiffness. Alternating between typing, writing, filing, and moving around in your work environment helps to keep muscles loose. Taking frequent short breaks When you are required to work on your computer for prolonged periods of time, take short breaks frequently. As a general rule, a 5- and 10-minute break every hour is a good idea. It is better to take short breaks frequently than longer breaks less frequently. Data shows that people who work for long periods of time without a break are more prone to injury. Occasionally stretch the muscles in your hands, arms, shoulders, neck, and back. You should stretch at least once an hour.