Impact of nitrogen dioxide pollution on paediatric asthma and premature mortality in South Africa

Nitrogen dioxide (NO₂), a priority pollutant and an indicator for Traffic-Related Air Pollution (TRAP), poses significant health risks including childhood-onset asthma and premature mortality. Routine measurements of NO₂ are severely limited in Pretoria and Johannesburg, two large cities in the industrialised Highveld of South Africa that experience severe air pollution due to road traffic. We use tropospheric columns of NO₂ observed with the TROPOMI instrument for 2019 and simulated NO₂ vertical profiles for the same year from the very high spatial resolution (~6 km) CAMx model driven with a locally developed emissions inventory to estimate ground-level NO₂. Near traffic-roadside ground stations, yearly averaged satellite-derived NO₂ ranges from 9 to 68 µg/m³, far in excess of the threshold for harm. Satellite-derived values agree with ground stations where sampling conditions are consistent, but validation is limited to a few sites. Underway is the use of the satellite-derived NO₂ to attribute asthma incidences and premature mortality to exposure to NO₂ and TRAP using state-of-knowledge exposure-response coefficients and Global Burden of Disease baseline rates of mortality and asthma incidences to motivate action to address severe air pollution in the industrialised Highveld.

Keywords

TRAP, Health Impact, satellite-derived, mortality burden, asthma, anthropogenic emissions, South Africa