Influence of the seasonality and of urban variables in the BTEX and PM2.5 atmospheric levels and risks to human health in a tropical coastal city (Fortaleza, CE, Brazil).

Abstract

The International Agency for Research on Cancer (IARC) classifies benzene in group 1 (carcinogenic to humans). Particulate matter (PM) has recently also been classified in this category. This was an advance toward prioritizing the monitoring of particles in urban areas. The aim of the present study was to assess levels of PM2.5 and BTEX (benzene, toluene, ethylbenzene, and xylene), the influence of meteorological variables, the planetary boundary layer (PBL), and urban variables as well as risks to human health in the city of Fortaleza, Brazil, in the wet and dry periods. BTEX compounds were sampled using the 1501 method of NIOSH and determined by GC-HS-PID/FID. PM2.5 was monitored using an air sampling pump with a filter holder and determined by the gravimetric method. Average concentrations of BTEX ranged from 1.6 to 45.5μgm-3, with higher values in the wet period, which may be explained by the fact that annual distribution is influenced by meteorological variables and the PBL. PM2.5 levels ranged from 4.12 to 33.0μgm-3 and 4.18 to 86.58μgm-3 in the dry and wet periods, respectively. No seasonal pattern was found for PM2.5, probably due to the influence of meteorological variables, the PBL, and urban variables. Cancer risk ranged from 2.46E-04 to 4.71E-03 and 1.72E-04 to 2.01E-03 for benzene and from 3.07E-06 to 7.04E-05 and 3.08E-06 to 2.85E-05 for PM2.5 in the wet and dry periods, respectively. Cancer risk values for benzene were above the acceptable limit established by the international regulatory agency in both the dry and wet periods. The results obtained of the noncarcinogenic risks for the compounds toluene, ethylbenzene, and xylene were within the limits of acceptability. The findings also showed that the risk related to PM is always greater among smokers than nonsmokers.