The physical environment of school buildings and school grounds is a key factor in the overall health and school buildings and grounds must be designed and maintained to be free of health and safety hazards and to promote learning. Studies have shown that student achievement can be affected either positively or negatively by the school environment. Policies and protocols must be in place to ensure food protection, sanitation, safe water supply, healthy air quality, good lighting, safe playgrounds, violence prevention, and emergency response, among other issues that relate to the physical environment of schools.