Author(s)

SHADUNG J. MOJA, PHUMUDZO THIVHAFUNI

Abstract

In this case study, the levels of nitrogen dioxide (NO₂), sulphur dioxide (SO₂), benzene (H₆C₆), tropospheric ozone (O₃) and particulate matter with aerodynamic diameter of 10 μm (PM10) were measured from June to December 2015 to evaluate the air quality status within the Ba-Phalaborwa municipality. Radiello diffusive sampling cartridges were used in duplicates to sample gaseous pollutants at the four selected monitoring sites. The cartridges were exposed for a period of one week (7 days) before being replaced with new unexposed ones. PM10 pollutant levels were measured continuously at each site with a portable active sampling unit (Met One E-sampler) equipped with meteorological sensors for wind speed and direction. Chemical analyses of all badges were performed by a South African National Accreditation System (SANAS) accredited laboratory. The highest average monthly NO₂ concentrations were measured at sites 3 and 4 with significantly higher concentrations measured during the dry period (18.8 μg/m³ at site 3 and 14.4 μg/m³ at site 4 in June) than during the wet period (3.7 μg/m³ at site 3 and 4.4 μg/m³ at site 4 in December) and similar trends were also attained at the other two sites. SO₂ and H₆C₆ average monthly concentration trends were similar to those measured for NO₂. In contrast to the concentration trends measured for NO₂, SO₂ and H₆C₆, the average monthly concentrations for ozone were relatively low from June to August months. All the gas pollutants measured did not exceed the South African Standards. All monitoring sites experienced episodes of non-compliance with respect to PM10 national ambient air quality standard of 75 μg/m³. The highest PM10 concentrations recorded were 187.13 μg/m³ at site 2; 155.48 μg/m³ at site 1; 140.59 μg/m³ at site 3 and 101.21 μg/m³ at site 4. The results provide baseline data to compare with future air quality assessments in Phalaborwa or other similar kinds of study areas.

Keywords

air quality, Radiello gas cartridges, NO₂, SO₂, C₆H₆, O₃, PM10, E-sampler