Physicochemical properties of smoke generated particles during charcoal-based meat preparation in an informal restaurant in the city of Johannesburg

Abstract

This study investigated the physicochemical properties of particles generated from different combustion phases. A total of three chicken grilling/ braaiing stalls were selected for physicochemical profiles of charcoal combustion particles. The samples were collected 1.5 m above the ground and 0.8 m away from the stove. Samples were collected in triplicate to minimize uncertainty making a total of 27 data points (in triplicates) for studying particle size distribution, mass and number concentration. Monitoring of particles was done using a real-time Nanozen DustCount 9000 Personal Dust Monitor. Samples for chemical assessments were collected on 37 mm PVC filters with a pore size of 5 µm. A Gilair pump at a flow rate of 2.2 l/minute was used to draw in the air over a monitoring campaign of 2 hours and 20 minutes per burning cycle. A PM_2,5 cyclone with a PM₄ cut-off point at 50% was attached to a cassette to isolate larger particles. The filters were subjected to acid digestion as a sample preparation step prior to analysis inductively coupled plasma mass spectrometry (ICP-MS). Coking phase had the highest number of particles with 2.20E⁺⁰⁸ ± 3.31E⁺⁰⁷#/cm³ (48%), followed by flaming with 1.54E⁺⁰⁸ ± 8.60E⁺⁰⁷#/cm³ (34 %) and ignition with 1.09E⁺⁰⁸ ± 3.38E⁺⁰⁷#/cm³ (18 %). Submicron particles contributed the highest number concentration in all phases. Using mass concentration, coking had the highest contribution of 41.6± 15.0 µg/m³ (38.0%), ignition 35.5± 8.8 µg/m³ (32.4%) and flaming 32.3± 2.1 µg/m³ (30 %). Aluminium was the highest emitted element with 1.3E^-01µg/m³ (43 %), followed by zinc 7.7E^-02 µg/m³ (25 %), magnesium 7.0 E^-02 µg/m³ (22 %) and chromium 1.4E^-02µg/m³ (5%). The particle mode was more towards the smaller particle size bin. These particles have atmospheric radiation forcing and health implications. We detected toxic heavy metals such as Cd, Cr, Pb and Hg. These metal leads to various health complications as they do not have a safe threshold. The study suggests a comprehensive health risk assessment for workers exposed to emissions from charcoal burning activities to develop the best risk management strategies