The current study was conducted to demonstrate the effects of air pollution on different biochemical parameters inCitrus aurantium plant and calculation the Air Pollution Tolerance Index (APTI). Five sites were selected tocollect plant leaves, four of them within the city of Baghdad, namely Al-Jadriya, Al-Andlous, Al-Doura and closeto the private generators to represent the urban areas and Abu Ghraib site to represent the rural area. Seasonalsamples were collected for the period from October 2016 to June 2017. Eleven biochemical parameters totalchlorophyll, ascorbic acid, leaf extract pH, relative water content, total nitrogen, total protein content, total sugarcontent, proline, electrical conductivity, cadmium and lead. The results of Citrus plant showed high chlorophyllconcentration and ascorbic acid content in private generator site reached to (10.620 mg/g and 0.403 mg/g)respectively. While relative water content recorded high concentration (57.563 %) at Al-Jadriya site. pH recordedhigh value (6.358) at Al-Doura site. In addition, values of APTI of the Citrus plant were calculated to determinethe sensitivity of the plant to air pollution. Highest value of APTI (6.23) was recorded at Al-Jadriya site, whilelowest value of APTI (5.03) was recorded at Al-Andlous site. The results of present study revealed that Citrusaurantium is sensitive to air pollution and can be used as bio-indicator under pollution stress. (PDF) Use Citrus aurantium plant as bio-indicator of air pollution in Baghdad city. Available from: https://www.researchgate.net/publication/379807094_Use_Citrus_aurantium_plant_as_bio-indicator_of_air_pollution_in_Baghdad_city [accessed May 07 2024].