Fumigation of plants with ozone in the field is most frequently carried out using open-top chambers (OTCs).

A great majority of the data used in developing the exposure-response relationships was obtained using (OTCs).

Charcoal- and particulate-filtered air, non-filtered air, or ozone-supplemented air is blown into the bottom layer, forced through the perforations into the plant canopy, and then allowed to escape through the top of the chamber.

The OTC exposure system was employed in the National Crop Loss Assessment Network (NCLAN) program from 1980 to 1988.

Plants grown in open-top chambers usually use different treatment levels, where

 

• Plants are exposed to air in chambers that attempt to take most of the ozone out of the chamber (carbon-filtered);

 

• Plants are exposed to air in chambers that are at ambient levels (non-filtered); and

 

• Plants are exposed to air in chambers where ozone is added at multiple levels (e.g., 2X).

 

Variable growth or injury responses are obtained when the biological endpoints are compared among different chamber treatments.