Estimation of Inhalation Risk due to Toxic Elements in Air Particulate Matter

G.G. Pandit, P. Kothai, I.V. Saradhi, V.D. Puranik and H.S. Kushwaha

Environmental Assessment Division Health Safety & Environment Group Bhabha Atomic Research Centre Mumbai, INDIA

     Abstract Number: 42
     Last modified: October 8, 2009

Abstract
Introduction

Suspended Particulate Matter (SPM) is a generic term used for particles in air pollution studies and is an important air quality parameter. Airborne particulates have many sources and contain hundreds of inorganic and organic compounds. Particulates of certain size are important in relation to health not only because they persist in the atmosphere for longer duration, but also they can penetrate respiratory system and thus they are named as Respirable Suspended Particulate Matter (RSPM). RSPM includes inhalable coarse particles with aerodynamic diameter ranging from 2.5 – 10 micro m and fine particles less than 2.5 micro m. Epidemiological evidence associating ambient particulate pollution with adverse health effects in humans is extensive. Some of the toxic pollutants in air are identified as Hazardous Air Pollutants (HAPs) by US EPA and the HAPs emitted from the industries can present a threat to human health as well as to the environment. In the present study ambient concentrations of coarse and fine particulate matter were measured at Trombay region, Mumbai and some of the trace elements designated as HAPs were measured using PIXE technique and the non-cancer risk due to inhalation has been estimated for adults and children separately.

Sampling and Analysis

GENT dichotomous air sampler is used for collection particles on nucleopore polycarbonate filters at an average flow rate of 16 lpm for a sampling period of 24 hours at a height of 15m. The site Trombay is located about 15km from the Mumbai main center and there are several other industries such as Petrochemical, Automobile, Metallurgical and Textile in and around the sampling area. Particle Induced X-ray emission (PIXE) was used to determine elemental concentrations from elements heavier than magnesium by exposing the filter samples to a proton beam accelerated with 2.5 million volts. The characteristic X-rays emitted were detected by means of a Si(Li) detector.

Results and Discussion

Concentrations of trace elements of environmental concern (Hg, Cr, Pb, Mn, Ni, Sb, Se, Ba and Cl) for coarse and fine fractions of Particulate matter were measured and the non-cancer risk characterization is performed. The intake of the chemical through inhalation route has been calculated using ambient elemental concentration, inhalation rate, body weight, and other exposure parameters like inhalation rate, exposure frequency, and exposure duration prescribed by US EPA in the Exposure handbook and the non cancer risk has been expressed in terms of Hazardous Quotient. The results of HQ values of coarse and fine particulate matter showed relatively higher values for children than the adults. However, the HQ values of all the elements are found to be insignificant even for the 95th percentile of the concentrations. Also no added hazards observed from the HQ values evaluated for children comparing with adults. The cumulative non-cancer hazard namely Hazard index (HI) derived by summing the hazard quotients of all the contaminants, also found to be less than one.