To some, cremation might be preferable for environmental reasons. Burial is a known source of certain environmental contaminants. Embalming fluids, for example, are known to contaminate groundwater with mercury, arsenic and formaldehyde. The coffins themselves are another known source of contamination. Another concern is contamination from radioisotopes that entered the body before death or burial. One possible source of isotopes is radiation therapy, although no accumulation of radiation occurs in the most common type of radiation therapy involving high energy photons. However, cremation has no effect on radioisotopes other than to return them to the environment more rapidly (beginning with some spread into the air). Thus, cremation is of no overall help with pollution from this source.

Yet another environmental concern, of sorts, is that traditional burial takes up a great deal of space. In a traditional burial the body is buried in a casket made from a variety of materials. In America the casket is often placed inside a concrete vault or liner before burial in the ground. While individually this may not take much room, combined with other burials it can over time cause serious space concerns. Many cemeteries, particularly in Japan and Europe as well as those in larger cities, have run out, or are starting to run out, of permanent space. In Tokyo, for example, traditional burial plots are extremely scarce and expensive, and in London, a space crisis led Harriet Harman to propose re-opening old graves for "double-decker" burials.

However, there is a growing body of research that indicates cremation has a significant impact on the environment as well:

• The major emissions from crematories are: nitrogen oxides, carbon monoxide, sulfur dioxide, particulate matter, mercury, hydrogen fluoride (HF), hydrogen chloride (HCl), NMVOCs, and other heavy metals, in addition to Persistent Organic Pollutants (POP).
• According to the United Nations Environment Programme report on POP Emission Inventory Guidebook,[14] emissions from crematoria contribute 0.2% of the global emission of dioxins and furans.