what is a stresssors
(December 2009). A stressor is a chemical or biological agent, environmental condition, external stimulus or an event that causes stress to an organism.An event that triggers the stress response may include: 1  environmental stressors (hypo or hyper-thermic temperatures, elevated sound levels, over-illumination, overcrowding).2  daily stress events (e.g., traffic, lost keys, quality and quantity of physical activity).n event that triggers the stress response may include: 1  environmental stressors (hypo or hyper-thermic temperatures, elevated sound levels, over-illumination, overcrowding). 2  daily stress events (e.g., traffic, lost keys, quality and quantity of physical activity).