Photo collage of a construction tractor at different scales.  From left to right, three bolts, a wheel with many bolts all around its perimeter, caterpillar treads around the wheel--which might be part of a tank, and a larger section of the machine itself, which includes the wheel, a large grabber, and a hydraulic arm. Only on the rightmost image can you tell that it's a piece of construction equipment. Photo by George E. Clark, used by permission.

Scale is another term that is used in everyday language that has specific meanings in different fields, including the social sciences.  For example, there is the technical definition in mapmaking that refers to the relationship between a distance measured in inches or centimeters on a map and the actual distance that it represents (say in miles or kilometers) in the real world.  Or, in the corporate world, you might ask if an idea is scalable--can you deliver more units of a service or make more widgets as the business grows to serve more and more clients across the country and the world.  Or, in the government world, a policymaker might see something works on a neighborhood level and ask would it also work at larger scales, such as city-wide, or when you add in suburbs across a metropolitan area, or when you try the same idea at the state, federal and global levels? This sense is close to that used by social scientists, who might also think about individual and family scales, as well as the larger ones mentioned above.

Many social scientists, though, have begun to think about other issues with scale, such as--what makes scale?  A good introduction is found in the Oxford Dictionary of Human Geography article "Scale":  This article introduces some of the questions: did not people invent political juristictions, nations, and so on? So what parts of scale are socially constructed, and what influences their creation and continuance over time ("reproduction")?  Or, in what scales is an activity taking place, like an point of sale transaction at a store?  You're spending money in a neighborhood. Your transaction may be logged in a multinational corporation or an international bank.  If you're travellling abroad, you're engaging exchange rates.  A state may regulate banks within its jurisdiction.  A town may have restrictions on how large a sign the store can display, or how many parking spaces, if any, it has to have.  A simple transaction be more complex than it first seems.

Scale is a concept that relates to environmental justice, too.  A neighborhood may be poor and have lots of toxins, but if data are reported at a county level, that instance of environmental injustice may disappear.  County-level land zoning may dictate where industrial activities take place, and the size of residential lots nearby, linking certain socioeconomic neighborhoods with environmental ills.  Yet, that neighborhood may also be downwind of a refinery, which happens to be located in another state, which changes the scale issues again.  The toxins themselves may be regulated at the national level, but enforced by delegated state agencies. Before you know it, scale can grow to be a very complicated thing, and it is worthy of study.  

Here are some sample Google Scholar searches related to environmental justice:

<scale AND "environmental justice">

<"geographic scale" AND racism AND "united states"> [The use of the term "geographic scale" helps avoid returning searches that have to do with another use of the word "scale," as in a rating scale--a tool to measure the severity or intensity of a phenomenon, like shyness, dyslexia, or stress.]

<scale toxicity France immigration>.