first attribute is object availability. Objects must be in a location that is useful, at a level where they can be retrieved, and must be organized to support the performance of the activity. Neither a sink that is too high for a wheelchair user nor a telecommunications device for the deaf (TDD) that is kept at a hotel reception desk is available. The second attribute is accessibility. Accessibility is related to the ability of people to get to a place or to use a device. Accessibility permits a wheelchair user to ride a bus or a braille user to read a document. The third attribute is the availability of sensory stimulation regarding the environment. Sensory stimulation, which can include visual, tactile, or auditory cues, serves as a signal to promote responses. Examples of such cues could include beeping microwaves, which elicit responses from people without hearing impairments, or bumpy surfaces on subway platforms, which tell users with visual impairments to change their location.

Table 6-1 presents some examples of enabling and disabling factors in the natural environment.

The natural environment may have a major impact on whether a limitation is disabling. For example, a person who has severe allergies to ragweed or mold, which can trigger disabling asthma, can be free of that condition in climates where those substances do not grow. The physical conditions still exist, but in one environment they may become disabling and in another environment they might not. Another example might be that a person who has limited walking ability will be less disabled in a flat geographical location such as Chicago than he or she would be in a hilly location such as Pittsburgh, although the person would also be more