Ideally, dogs should be taken to council-designated areas where they can be safely let off the leash to run free. It is important to use these specifically designated areas not only to ensure their own safety (preventing the risk of being hit by a car) but also the safety of farm livestock and wildlife which can be threatened by a dog let loose in their habitat.
It is important to note however that dogs who are never, or seldom allowed indoors, are more likely to become bored - and as a result become disruptive (e.g. bark for attention) and/or destructive (e.g. dig up your newly- planted rose bush). This is because dogs associate their human family as their pack and can develop behavioural issues if they feel neglected as a consequence of being excluded from interacting with their pack.
Puppy Roundworms can infect humans. To prevent this infection, puppies should be wormed regularly throughout their first year of life, and owners should be thorough with their own personal hygiene after having interacted with the dog. Tapeworms, Hookworms, and Whipworms can also infect dogs, and your veterinary surgeon can advise when to worm the dog.