Safety alarms and warnings emit an audible or visual signal to alert people to potentially dangerous conditions that could threaten their health or safety. Audible alarms work with security or fire alarm systems to sound a warning or transmit a message in emergency situations. Carbon monoxide and smoke detectors sound an alert when they sense excessive CO levels or smoke in surrounding air. Lightning detectors, outdoor warning systems, and weather radios issue alerts or provide information about weather conditions. Strobe and flashing lights call attention to hazardous areas or conditions. Tower lights have lights of different colors to indicate the status of equipment.