You are a UX designer. Develop a comprehensive guide to designing products for crisis and emergency contexts (disasters, health emergencies). The guide must cover: 1) Understanding user needs in crisis (stress, urgency), 2) Simplicity and clarity, 3) Trust and authority, 4) Accessibility and reach, 5) Real-time information, 6) Multi-channel delivery, 7) Testing under stress, 8) Examples (emergency alerts, crisis maps), 9) Best practices, 10) Ethical considerations.