Indoor and outdoor air pollutants concentrations at preschools in Melusi informal settlement, Pretoria, South Africa

Abstract

Air pollution remains a major public health concern in Africa, contributing to an estimated 1.1 million premature deaths annually, with approximately 65% linked to residential exposure. This study assessed indoor and outdoor sulphur dioxide (SO₂) and nitrogen dioxide (NO₂), as well as indoor benzene, toluene, ethylbenzene, and xylene (BTEX), in eight selected preschools within the Melusi informal settlement, Pretoria, South Africa. Pollutants were measured using Radiello passive samplers over a 14-day period. Indoor concentrations ranged from 0.18 to 1.15 µg/m³ for SO₂ and 10.09–22.35 µg/m³ for NO₂, while outdoor levels ranged from 0.45 to 1.90 µg/m³ and 14.09–30.25 µg/m³, respectively. Indoor BTEX concentrations varied from 2.24 to 30.11 µg/m³ for benzene, 5.12–13.30 µg/m³ for toluene, 1.46–6.65 µg/m³ for ethylbenzene, and 1.40–4.06 µg/m³ for xylene. The highest pollutant levels were recorded in preschools using mixed or solid fuels and those located near waste-burning sites or unpaved roads. Indoor/outdoor ratios indicated substantial outdoor infiltration. These findings underscore the urgent need for cleaner household energy, improved ventilation, implementation of indoor air quality policies, and education programs for preschool educators and caregivers to protect children’s health in informal settlement preschools.