ISEE-8 Abstract: Air pollutants are related with cardiovascular morbidity and mortality. Objective: In order to investigate the effects of urban air pollutants on blood markers for cardiovascular risks (fibrinogen, high-sensitivity C reactive protein -HSCRP, and mucoprotein) we carried out a panel study with 48 traffic controllers working in high traffic avenues in São Paulo City. Methods: All participants were males, mean age of 39.2 years (± 6.4), non-smokers, with at least complete high school education, and healthy. Blood samples were collected in working days, in three different periods: August 2000 (winter), January/February 2001 (summer), and August 2001 (winter), corresponding to different mean levels of air pollutants exposure. Linear regression models with generalized estimating equations (GEE) were used to assess the effect of particulate matter with an aerodynamic diameter less than 10 mm (PM10), CO, SO2, NO2, and O3 on the blood markers, controlling for temperature, humidity, age, and body mass index. Results: CO, SO2, PM10, and O3 where associated with changes in blood markers. In general, the effects presented short time lags. An interquartile range increase of CO (1.1 ppm) was associated with an increase of 25.78 mg/dl on fibrinogen (95% CI: 8.12–43.44), increase of 1.66 mg/l on HSCRP (95% CI: 0.09–3.23), and 0.28 mg/dl on mucoprotein (95% CI: 0.02–0.42). An interquartile range increase of SO2 (9.6 mg/m3) was associated with an increase of 0.49 mg/dl on mucoprotein (95% CI: 0.28–0.70), increase of 1.48 mg/l on HSCRP (95% CI: 0.22–2,74). An interquartile range of PM10 (33.6 mg/m3) was associated with increases of 0.34 mg/dl on mucoprotein (95% CI: 0.01–0.67). An interquartile range increase of O3 (42.6 mg/m3) was associated with increase of 0.25 mg/dl on mucoprotein (95% CI: 0.08–0.42). Conclusion: In São Paulo City, primary pollutants presented positively association with, at least, one of the blood markers of cardiovascular risk. These results are in agreement with other studies focusing the same endpoints and with our studies that showed air pollution effects on heart rate, blood pressure and other blood markers in the same population. Also, they reinforce the epidemiological association between air pollution and cardiovascular deaths reported in time-series studies.