Take a Walk in the Park Day

What the day is

Take a Walk in the Park Day is observed on March 30. The general case for walking is made on other days in the calendar; this one is about the park specifically, which turns out to be doing more than providing somewhere to walk.

Origin and background

The research that opened the field was published in 1984 and was almost accidental. A hospital had two sets of otherwise similar rooms, one looking onto trees and one onto a brick wall, and patients recovering from the same operation were assigned to them essentially at random. Those with the view of trees left hospital sooner and needed less strong pain medication. The study was small, and much of what followed has been mixed, but it established that a view of greenery was something worth measuring at all, and a large literature now links access to green space with lower stress and better mental health.

Parks also do something physical and uncontroversial. Cities are hotter than the land around them, because masonry and asphalt absorb heat through the day and release it at night, and a park interrupts this: shade blocks the sun, and water evaporating from soil and leaves carries heat away. The temperature difference between a park and a nearby street can be several degrees on a hot afternoon, and it extends some distance into the surrounding blocks. As heatwaves become more severe, that is a public health function, not an amenity.

The difficulty is that access is uneven. Studies in many cities find that lower income neighborhoods have less park space, and often less tree cover, than wealthier ones in the same city, so the cooling and the health benefit land where they are needed least.

Public parks were largely a nineteenth century invention, argued for at the time in explicitly public health terms.

How to take part

• Go to a park rather than just going for a walk. The difference is measurable.
• Leave the headphones out for part of it and listen to what is there.
• Notice the temperature change as you walk in from the street.
• Support your local parks department or a friends-of group.
• Ask which neighborhoods in your city have the least tree cover.