Project at a Glance

Title: Demonstration of the effects of smog on ornamental and home garden plants.

Contractor: California Arboretum Foundation, Inc. and Department of Arboreta and Botanic Gardens

Contract Number: A733-138 & A833-137

Research Program Area: Ecosystem & Multimedia Effects

Topic Areas: Ecosystem Impacts


The California Air Resources Board and the Los Angeles State and County Arboretum funded the Air Pollution Greenhouse display to increase public awareness of the effects of existing air quality on plants commonly found in yards and gardens in the greater Los Angeles area. A home and its yard and garden represent major investments for owners. Programs to provide clean and healthy air are expensive and require extensive public support to be successful. If the program to clean up the air is perceived to benefit the home owner, it is more likely that people will be cooperative and supportive as the control program rise in cost and impact more and more of people's everyday living activities.

Over 140,000 visitors have seen, touched and smelled plants grown in a filtered air greenhouse and compared their appearance with the same age and type of plant grown in a matching layout in a greenhouse containing ambient air. From children to adults, students to scientific researchers, home gardeners to landscapers--all have had their knowledge about air quality enhanced by a tour through the Air Pollution Greenhouse.

The Air Pollution Greenhouse is a working research facility which provides a controlled environment in which to grow ornamental and home garden plants. Over 100 varieties of plants have been grown under identical environmental conditions except for air quality. Many exhibit a syndrome of air pollution injury symptoms. The most common effects have been pale or yellow leaves and other color changes; leaf spots which vary in size and severity; reduced size and number of leaves, flowers or fruits; reduced growth and vitality and a shortened life span for different plant organs or for the entire plant. Some other effects have been reduced resistance to insect pests and a smaller root system. Previous research on the impact of pollution on ornamental plants has demonstrated acute visible damage such as leaf spots, but no publications are available which include more than a few examples. In this project, photographs taken every two weeks against a standard background. These photographs have been used to document the response of vegetation in the Air Pollution Greenhouse. Comparable information on other types of ornamentals is not available.

The Air Pollution Greenhouse facilities consist of a greenhouse divided into two sides, one of which is equipped with charcoal filters to remove air pollution. Air quality monitoring equipment is installed and documents that the clean air side of the greenhouse is free from measurable amounts of ozone and oxides of nitrogen, two pollutants known to create air pollution injury to vegetation. Air pollution levels in the unfiltered side of the greenhouse vary with the season. The exhibit also includes an Information Center with information oriented to the general public and covering such topics as how air pollution is formed, what effects it has on people and vegetation. Information is provided on what can be done to reduce pollution. Tour guides, posters, a slide show and brochures are used by the visitor to learn to recognize air pollution symptoms. The visitors are then encouraged to tour the greenhouse display and identify the symptoms on the plants in the greenhouse. Some of the plants in the greenhouse always show air pollution symptoms. Prior to the time of year when the smog levels are high enough to cause air pollution symptoms, a fumigation chamber is used to provide plants with air pollution damage.

The response of the public to this display has been excellent and extensive coverage has been provided by area television stations, large circulation newspapers and popular magazines.

A comprehensive program has been undertaken to upgrade the display, in response to visitors comments and requests. The staff of the Air Pollution Greenhouse have learned that it is not enough to provide the public with a simple greenhouse containing plants. Air pollution symptoms are difficult to recognize and modifications to the display have been required to make it possible for visitors to recognize the damage. The improvements required included big, easy to read signs and examples of what to look for on the plants. Photographs which clearly illustrate the symptoms are hung over every plant in the exhibit, prompting the viewer to look for specific symptoms. The same information must be provided in different ways. Visitors prefer to see pictures of the plants, rather than read about them. If a real plant is displayed, the visitors prefer that to the picture. A slide show is preferred to wall charts and posters, but displaying the air quality monitor without wall charts and posters to explain it is confusing. Staff has applied the standard teacher's formula of "Tell them what you are going to tell them, tell them the information, and tell them what you just told them. The combination of this technique and the same type of scientific design criteria used in other types of research on the impact of air pollution on vegetation have made the Air Pollution Greenhouse Exhibit a success.

Many requests been made for copies of the photographs, but providing them to all who ask is clearly beyond the scope of this project. A questionnaire was used to evaluate visitor satisfaction; over 95% rated the exhibit as informative and interesting. Many left the display concerned about the problems of poor air quality and perhaps more willing to do something about improving it.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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