What does precautionary really mean in planning? Overstating its benefits? Or?

From Linsey Marr and my contribution to the forthcoming Oxford Handbook of Urban Planning:

This chapter’s goal has been to expand planners’ scope of the connections between land use, urban form, air quality and community health. Indeed, planning research and practice has significant opportunities to contribute to working with the many issues at stake with urban environmental health, air quality, and climate change. In order to do so, however, the field has to recognize that there many issues other than the automobile and its emissions. Significant though those issues are, they are only one part of the story about environmental health—the beginning.

For those who believe that land development will change radically, and that those changes will affect how much fuel consumption occurs, this chapter may seem overly cynical, assigning a smaller role to planning and design than they merit in environmental health. Instead, this chapter is merely a call to complexity, one that planners can and should answer in the interest of being truly precautionary in our planning. More cynical would be to see no evil, hear no evil, and speak no evil about these uncertainties when failure to deliver on environmental health improvements results in continued human suffering.