Explain how environmental and policy factors affect physical activity levels

Often considered part of the environmental level is the policy level. Environmental and policy factors have the potential for making profound changes at the population level. Policy refers to the legislative, regulatory actions taken by local, state, or federal governments that are meant to influence behavior by demanding specific behaviors or inhibiting others; policies may be implicit (e.g., informal policy at work) or explicit, and policy interventions require public support. Policies can indirectly influence physical activity by influencing the safety of neighborhoods, adding more public transportation, creating and supporting physical activity programs, and increasing access to physical activity opportunities, but they also can impact physical activity directly by encouraging people to use structures in the environment that facilitate physical activity. Policies can also influence the design of a city, which can consequently facilitate physical activity by adding or improving parks and walking and bicycle trails. However, there have been limited studies showing changes in physical activity following the implementation of policies promoting physical activity.?