Beyond smoke: culturable airborne bacteria associated with informal waste burning in peri-urban South Africa.
- 1Department of Geography, Environmental Management and Energy Studies, University of Johannesburg, Johannesburg, South Africa.
- 2Department of Environmental Health, University of Johannesburg, Johannesburg, South Africa.
- 3South African Medical Research Council, South Africa.
Abstract
Introduction
Informal waste burning is an established source of particulate matter and hazardous combustion emissions in many low- and middle-income settings, yet its potential contribution to biological airborne exposure remains poorly characterized. This study investigated culturable airborne bacteria in active informal waste-burning environments in Hammanskraal, South Africa, and examined their spatial variability and potential relevance to environmental exposure.Methods
A cross-sectional exploratory field investigation was conducted at three active informal waste-burning sites and one non-burning comparison site. Active air samples were collected using a Sampl'Air Pro impactor onto Tryptic Soy Agar at approximate distances of 25, 50 and 100 m from visible combustion areas. Culturable airborne bacterial concentrations were quantified as colony-forming units per cubic meter (CFU/m³), and representative cultured isolates were characterized using the Vitek Compact 2 microbial identification system. Structured field observations documented combustion intensity, waste characteristics, smoke-plume behavior and local environmental conditions.Results
The highest culturable airborne bacterial concentrations occurred at active waste-burning sites, although concentrations varied substantially among sites. Burn-site concentrations ranged from 91 CFU/m³ to above the analytical upper quantification limit (>1,259 CFU/m³), compared with 35-260 CFU/m³ at the comparison site. Sampling distance was weakly associated with bacterial concentration (Spearman's ρ = -0.14, p = 0.701; exploratory linear regression R² = 0.02). Thirty-nine representative isolates were characterized. Gram-positive bacilli constituted the largest phenotypic grouping, while Sphingomonas paucimobilis, Pantoea spp. and several other environmentally associated or opportunistic taxa were recovered across the sampled environments.Discussion
Active informal waste-burning environments contained viable culturable airborne bacteria, with markedly elevated concentrations observed at some burning sites relative to the non-burning comparison environment. Distance from active combustion alone did not explain the observed spatial variability; site-specific factors including combustion intensity, plume behavior, environmental disturbance and local meteorology may influence short-term bioaerosol occurrence and warrant investigation using more highly replicated designs. These findings identify viable culturable bacteria as an under-characterized component of informal waste-burning environments and provide a basis for future integrated studies of environmental occurrence, human exposure and potential health relevance.
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BibTeX
@article{kwakwa2026beyond,
title = {{Beyond smoke: culturable airborne bacteria associated with informal waste burning in peri-urban South Africa.}},
author = {Boitemogelo O Kwakwa and Shalin Bidassey-Manilal and Natasha Naidoo and Isaac T Rampedi},
journal = {Frontiers in public health},
year = {2026},
month = oct,
doi = {10.3389/fpubh.2026.1965626},
url = {https://europepmc.org/article/MED/42908911},
note = {CC BY},
}
RIS
TY - JOUR
TI - Beyond smoke: culturable airborne bacteria associated with informal waste burning in peri-urban South Africa.
AU - Boitemogelo O Kwakwa
AU - Shalin Bidassey-Manilal
AU - Natasha Naidoo
AU - Isaac T Rampedi
PY - 2026
DA - 2026/10/07
JO - Frontiers in public health
DO - 10.3389/fpubh.2026.1965626
UR - https://europepmc.org/article/MED/42908911
AB - Introduction Informal waste burning is an established source of particulate matter and hazardous combustion emissions in many low- and middle-income settings, yet its potential contribution to biological airborne exposure remains poorly characterized. This study investigated culturable airborne bacteria in active informal waste-burning environments in Hammanskraal, South Africa, and examined their spatial variability and potential relevance to environmental exposure.Methods A cross-sectional exploratory field investigation was conducted at three active informal waste-burning sites and one non-burning comparison site. Active air samples were collected using a Sampl'Air Pro impactor onto Tryptic Soy Agar at approximate distances of 25, 50 and 100 m from visible combustion areas. Culturable airborne bacterial concentrations were quantified as colony-forming units per cubic meter (CFU/m³), and representative cultured isolates were characterized using the Vitek Compact 2 microbial identification system. Structured field observations documented combustion intensity, waste characteristics, smoke-plume behavior and local environmental conditions.Results The highest culturable airborne bacterial concentrations occurred at active waste-burning sites, although concentrations varied substantially among sites. Burn-site concentrations ranged from 91 CFU/m³ to above the analytical upper quantification limit (>1,259 CFU/m³), compared with 35-260 CFU/m³ at the comparison site. Sampling distance was weakly associated with bacterial concentration (Spearman's ρ = -0.14, p = 0.701; exploratory linear regression R² = 0.02). Thirty-nine representative isolates were characterized. Gram-positive bacilli constituted the largest phenotypic grouping, while Sphingomonas paucimobilis, Pantoea spp. and several other environmentally associated or opportunistic taxa were recovered across the sampled environments.Discussion Active informal waste-burning environments contained viable culturable airborne bacteria, with markedly elevated concentrations observed at some burning sites relative to the non-burning comparison environment. Distance from active combustion alone did not explain the observed spatial variability; site-specific factors including combustion intensity, plume behavior, environmental disturbance and local meteorology may influence short-term bioaerosol occurrence and warrant investigation using more highly replicated designs. These findings identify viable culturable bacteria as an under-characterized component of informal waste-burning environments and provide a basis for future integrated studies of environmental occurrence, human exposure and potential health relevance.
SN - 2296-2565
ER -