Visual Air Quality in Recreational Settings

During the past decade, an experience-based demand model has been developed to assess demand for recreational opportunities. The model incorporates visitor demand for activities, for social/physical/managerial site attributes, and for the realization of specific psychological satisfactions.

The model was used to investigate the psychological value of good visual air quality at Grand Canyon, Mesa Verde, Great Smoky Mountains, Mount Rainier, and Everglades National Parks using on-site interviews and mail-back surveys. The purpose was to evaluate the importance of visual air quality relative to other park attributes, to determine if visitors were accurately aware of changes in visibility, and to ascertain whether relationships existed between visual air quality and visitor satisfaction (Ross et al., 1985, 1987).

Importance of Good Visual Air Quality. The importance of good visual air quality to park visitors was evaluated by having visitors rate how important specific park attributes were to their recreational experience. Cluster analysis was used to statistically identify similar types of attributes based on response patterns. Grand Canyon National Park's attributes, their corresponding mean importance scores, and cluster formation are shown in Figure 29. The "clean, clear air" attribute ranked third in importance and combined with attributes that are descriptive of a clean, natural setting, which, as a group, were slightly more important than the cluster of view-related attributes. This indicates that visitors interpret "clean, clear air" as being an integral part of the cleanliness of the park and as such, an important part of the overall recreational experience sought at Grand Canyon.

The importance of a natural, clean environment with clean air was not unique to Grand Canyon visitors. Figure 30 shows that similar findings resulted from the other studies regardless of park location or overall theme. The cleanliness attribute cluster, which included "clean, clear air," was the most important cluster at all five parks.

Visitor Awareness of Visual Air Quality. In a random sample, nearly 1800 visitors at Grand Canyon National Park were asked during an interview if they were aware of any haze and, if so, how hazy they thought it was. Results from correlation analysis between awareness of haze and standard visual range measures showed that visitors' awareness of haze increased as visibility decreased. Correlation coefficients

TABLE 2 Summary of Contrast and Color Change Threshold Data

Contrast

AE

Percent Detection

Edge

Reference

0.003"

50

Sharp

Blackwell (1946)

0.014

?

Sharp

Lowry (1931, 1951)

0.007*

?

Sharp

Howell and Hess (1978)

0.009*

?

Diffuse

0.016c

?

Sharp

1

30

Sharp

Jaeckel (1973)

2

50

Sharp

3

70

Sharp

4

90

Sharp

0.006

1

10

Diffuse

Malm et al. (1980)

0.009

1.5

25

Diffuse

0.014

2.3

50

Diffuse

0.02

3.3

75

Diffuse

0.025

4.2

90

Diffuse

0.01

90

Sharp

Loomis et al. (1985)

0.005d

70

Sharp

Malm et al. (1985)

0.010"

70

Sharp

0.0207

70

Diffuse

Ross et al. (1988)

0.007d

70

Diffuse

Ross et al. (1990)

0.025e

70

Diffuse

"The most sensitive contrast reported for largest size of stimulus and largest luminance and longest response time evaluated (probably the minimum possible threshold).

AThe most sensitive contrast reported at a spatial frequency of 3 cycles/degree.

Threshold contrast for sharp objects at low spatial frequencies.

''Minimum threshold for 0.36° wide plumes.

^Maximum threshold for all size plumes tested.

^Threshold contrast reported for light-colored, diffuse edge hazes of varying size.

"The most sensitive contrast reported for largest size of stimulus and largest luminance and longest response time evaluated (probably the minimum possible threshold).

AThe most sensitive contrast reported at a spatial frequency of 3 cycles/degree.

Threshold contrast for sharp objects at low spatial frequencies.

''Minimum threshold for 0.36° wide plumes.

^Maximum threshold for all size plumes tested.

^Threshold contrast reported for light-colored, diffuse edge hazes of varying size.

Visual Air Quality and Recreational Behavior. A laboratory study conducted by Malm et al. (1984) at Grand Canyon National Park examined how visual air quality might affect visitor behavior. Participants examined sets of photographs with different levels of visual air quality and indicated how they would be willing to spend a given amount of time either driving to a lookout point or touring an archaeological site. The study concluded that subjects place a high value on visual air quality and would be willing to significantly alter behavior for increased visual air quality. For example, subjects would be willing to spend an additional 2.5 h driving time to view a dominant distant landscape for a 0.01 km"1 reduction in atmospheric extinction. The study also showed that vistas that lacked color and texture were insensitive to increases in atmospheric extinction.

Disclaimer. The assumptions, findings, conclusions, judgments, and views presented herein are those of the author and should not be interpreted as necessarily representing official National Park Service policies.

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