The Environmental Protection Agency outlines the protective measures people can take against ionizing radiation as being time, distance and shielding. Taken together, these three factors determine the severity of exposure to radiation, including gamma ray radiation, and the likelihood of long-term health effects.
According to the EPA, all three types of ionizing radiation, alpha, beta and gamma, can be treated as similar for the purposes of personal protection against exposure. The first line of protection against exposure to gamma radiation is time. The less time spent in the presence of ionizing radiation, the lower the exposure level is likely to be. Limiting the time spent in proximity to a gamma-ray emitter is therefore the easiest way to avoid a dangerous exposure.
Distance is another measure that contributes to the degree of exposure. The EPA states that radiation intensity declines faster than distance from the source because, while distance is a two-dimensional measure, radiation propagates in three dimensions and so grows exponentially weaker with distance.
Still another form of protection the EPA advises consists of having adequate shielding from the radiation. For alpha radiation, shielding is relatively easy, as alpha particles don't usually have the energy to penetrate skin. Gamma rays, on the other hand, call for thick lead shielding between the person and the source material.