complete evaluation of suspended air particles and their composition in the central area of yazd city

introduction: air pollution is one of the problems of the recent century caused by vehicles, industries and other urban activities. the city of yazd faces air pollution due to its high population, vehicular traffic and industrial places around the city. one of the important parameters of air pollution is suspended air particles that have harmful effects on the health of people, plants and objects. methods: this research has been carried out by first determining a station in the central area of the city (shahid beheshti square of yazd). the suspended particles were measured during a five-month period from march to july, 2006. a high volume sampler was used for measuring total suspended particles (tsp). the amount of lead content of tsp was measured in samples by using atomic absorption method. in the next stage, the percentage of organic and inorganic particles in the tsp of all samples was measured by using gravimetric methods and by burning in the oven. results: the results of this study showed that amount of suspended particles in the city of yazd is higher than national standard and the general mean average of the suspended particles of air in five months was 233 micrograms per cubic meter. the average concentration of suspended air particles from end of march to august during the five month period was 118, 193, 231, 267and 333, respectively. the average concentration of lead was 0.04 microgram per cubic meter and amount of organic and inorganic particles in tsp was 25.31% and 74.68%, respectively. conclusion: with respect to the results, the minimum amount of tsp concentration was in march. this could be due to reduction in trading and industrial activities and new year vacations. in addition, the average monthly tsp increased from march to july the cause of which could be relative decrease in humidity and increase in temperature. the amount of lead in samples was much less than standard, which could be due to omission of lead from petrol used in the city.