As an essential micronutrient, iron (Fe) has significant effect on the activity of antioxidant enzymes and thereby influences the crop tolerance to environmental stresses. On the other hand, environmental stresses i.e., air pollution might modify Fe nutritional status of plants by affecting the activity of antioxidant enzymes. In fact, the antioxidants considered as the plant response to stresses, while they are dependent on Fe concentration in plants. To our knowledge, there is a lack of information on this regard. Therfore, the purpose of this study was to investigate the impact of air pollution on Fe nutritional status of plants. This study was conducted in two phases. The first phase was done in an open field to analyze the effects of air pollution caused by industry and traffic of vehicles on the plants iron status. In this part of the research considered two areas as infected areas and maple ( Acer negundo L.) and plantain ( Plantago major L.) were sampled as the test plants at different distances from the areas. The results showed by increasing the distance from Oil Refinery of Shiraz (ORS) Fe, Zn, chlorophyll concentration and enzymes activity of catalase (CAT) and peroxidase (POD) in the maple and plantain leaves increased. Our data support the hypothesis that the severity of Fe deficiency-induced chlorosis symptoms on maple and plantain leaves is associated with air pollution. In our study, CAT and POD activity showed a marked decrease in leaves of maple trees and plantain near the air pollutants sources. However, this decrease may not be a specific response to air pollution and it could be also due to lower Fe concentration in plant leaves. No regular pattern was observed for changes in the measured parameters with distance from the urban traffic of Imam Hossein square (AS), as another major source of air pollution in the studied region. This was due to irregular changes in the concentrations of air pollutants across the sampling pathway. Although many factors including soil properties may be effective in this regard, considering the similarities observed in the characteristics of the studied soils, it can be concluded that there was a close relationship between the Fe nutritional status of plants and intensity of air pollution. The second stage of the study was aimed to investigate how exposure to Sulfur dioxide (SO 2 ), as one of the major air pollutants, would affect plantain responses in a controlled environment. In this experiment, thirty days after seed germination, plants were unexposed or exposed to SO 2 (3900 ?g m -3 ). Fumigation with 3900 ?g m -3 O 2 was performed for 3 h daily for 3 days a week (alternate day) in a 100 × 70 × 70-cm traarent polythene chamber (0.25 mm) which ambient air was circulated by means of a fan. Half of the plants were non-supplemented and another half were supplemented with Fe as foliar application (3 g Fe L -1 in the form of FeEDDHA). Sulfur dioxide was provided by allowing a reaction of dilute sulfuric acid (10% H 2 SO 4 ) and sodium sulfite (Na 2 SO 3 ). Plant responses i.e., iron, zinc and total sulfur concentration, CAT and POD activity, chlorophyll a, b and carotenoids concentration and cell wall compounds were measured. Based on the results obtained, exposure to SO 2 , as one of the major gaseous air pollutants negatively affected Fe nutritional status and amplified Fe deficiency chlorosis in plantain. Also activity of CAT and POD enzymes increased under SO 2 pollution. Although effect of foliar application of Fe in increasing tht enzymes activity was higher than that of SO 2 . Chlorophyll a, b and carotenoids concentration reduced in the plants exposed to SO 2 . The reduction of chlorophyll concentration in the presence of SO 2 gas shows the degradation of chlorophyll molecule as a result of the production of H + and HSO 3 - ions in the cytoplasm. Exposure to SO 2 led to reduced cellulose (28.1 percentag) but enhanced lignin content of plant leaf cell wall. In contrast, application of Fe increased cellulose content (47.8%) of the leaf cell wall. Regardless of foliar application of Fe, the lignin content was higher in plants exposed to SO 2 in comparison with those unexposed to SO 2 .