Occupational exposure to atmospheric pollutants in traffic wards

Objective: Aim of the work was the assessment of occupational exposure to atmospheric pollutants in traffic wards in Milan. Considered pollutants were: carbon monoxide (CO), particulate matter (PM) including respirable fraction and PM2,5 (fine particles). Material and Method: One hundred thirty local urban policemen were monitored in four different seasonal campaigns (May, July, October and December 2004). Exposure monitoring was performed in working day (Monday to Friday) between 7:00 AM to 1:00 PM (1st workshift) and from 1:00 PM to 7:00 PM (2nd workshift). Personal exposure was measured by means of CO electrochemical cell (equipped with datalogger), personal sampler equipped with Lippmann, and GK2.05 cyclone for respirable and PM2.5 respectively. In both cases particles were collected on Zefluor membrane (2 μm porosity). PM samples were gravimetrically examined and then analyzed in terms of inorganic ions composition (NH4+, Ca2+, Cl-, SO42-, NO3-). The same pollutants data were contextually acquired by mobile environmental station (located near the working cross and street of the policeman), and by the fixed monitoring urban net of the Regional Environmental Protection Agency. Results: Personal exposure to PM2.5 and respirable fraction ranged respectively from 51 μg/m3 to 203 μg/m3 and 128 μg/m3 to 429 μg/m3. Respirable particles level varies wide in different seasonal campaigns (from a mean of 99 μg/m3 of July to 152 μg/m3 of December). Compositional ion analysis shows no significative differences in the two different fraction. The mean composition of PM in the city of Milan was: NO3- 5%, SO42- 3.1%, NH4+ 1.7%, Ca2+ 1.6%, K+1, 1%, Na+ 0.3% Cl- 0.5%, NO2- 0.04%. Conclusion: PM concentrations for both fraction (PM2.5 and respirable) were above the PM10 actual daily limit of 50 μg/m3. Respirable fraction concentrations follow a seasonal trend and the increment in winter season was defined by the presence of addictive sources as heating plant and atmospheric conditions. The personal exposure respirable fraction follow the PM10 trends of fixed net but the concentrations were always above showing that environmental monitoring underestime the effective personal exposure.