Ozone has become an all pervasive air pollutant in the Northeastern USA.  Some of it is generated locally, but much of our ozone, and its precursors, comes to us on prevailing winds from the metropolitan New York area. Pollution level ozone can injure sensitive plants, affect growth and reproduction and may alter species diversity. Ambient ozone can be detected by mechanical monitors or by the use of bioindicator plants, that exhibit specific foliar injury symptoms when exposed to above natural background levels of ozone.  Sentinel bioindicators are introduced plants that receive cultural care.  They indicate the potential for ozone injury. Detector bioindicator plants are native plants that respond to ozone only when soil and air conditions promote photosynthesis and ozone uptake.  In the Boston Metropolitan Air Quality Region, which includes the Boston Harbor Islands Park, air quality for ozone in the summer months exceeds the US EPA's standard. Air quality is not monitored in the Boston Harbor Islands Park and there is no assessment of air pollution effects.  The use of sentinel bioindicators and surveys of potential detector plants on the Harbor Islands would be useful in assessing relative air quality and ozone effects on plants.