Tomato plants established in containers of soil with different oxygen diffusion rates were subjected to airborne oxidants for short periods of time. The supply of oxygen to plant roots, or the oxygen diffusion rate, influenced the susceptibility of plants to airborne oxidants. Plants growing in soils with oxygen diffusion rates of 16 to 24 x 10/sup -8/ g. cm./sup -2/ min./sup -1/ were not damaged by peroxyacetyl nitrate (PAN) or ozone. Plants growing in soils with oxygen diffusion rates of 34 to 90 x 10/sup -8/ g. cm./sup -2/ min./sup -1/ were moderately to severely damaged by both PAN and ozone. Water-use data and plant symptoms were an indication of reduced plant vigor at the lower-oxygen treatments. Soil oxygen diffusion rates taken in field plots show that limited oxygen supply to plants could affect the susceptibility of plants to airborne oxidant damage under field conditions. 9 references, 3 figures, 2 tables.