Quantifying particulate emissions from domestic burning in the kwaDela township, Mpumalanga

Abstract

Air quality in South African low-income residential areas is poor owing to high gaseous and particulate emissions from a range of sources including domestic burning. These emissions degrade ambient air quality, result in indoor air pollution which has a negative impact on human health. Solid-fuel use and emissions in a household setting are governed by several factors that vary in space and time. This raised a need to collect local reliable solid-fuel use and emissions data. The output is used to understand the relationship between burning behaviour, emissions patterns and ambient air quality. Characterising solid-fuel use and quantifying emissions from domestic burning is the first step to improving air quality in low-income residential areas. Emission factors from domestic burning are sensitive to fuel characteristics, stove-operation behaviour and conditions, therefore, cannot be generalised. The absence of data on fuel use and variability in low-income residential areas introduces uncertainties when quantifying estimates of total emissions from the township. Unreported high uncertainties in emission estimates lead to the development of misinformed emission inventories. The study aims to quantify emissions of fine particulate matter from domestic burning of coal using field measurements. The first objective of the study is to characterise solid-fuel use and burning-device operation behaviour. The second objective quantifies fine particulate emission factors from domestic burning and characterises the operational behaviour effect of stoves on emission profiles. The last objective estimates the annual, seasonal and daily fine particulate matter emissions from domestic burning in a low-income residential area. Solid-fuel use responses from a survey undertaken in kwaDela (2014) and observation results (2016) were used to identify the dominant solid-fuel and burning-device used; the major household solid-fuel use determinant and describe burning-device operation behaviour. Stove-use monitors (K-type I-Button) data (for 2013 winter and 2014 summer) were used to characterise seasonal burning patterns in the township. To quantify fine particulate PM 2.5 emission factors (g.kg-1), isokinetic (2015) and direct (2014) field tests were set up to monitor and sample gaseous and fine particulate concentrations during a burning event. A Monte Carlo simulation model was used to compute the residential area’s probable seasonal fine particulate emission estimates from domestic burning. Coal is the predominantly used fuel. Traditional cast-iron coal stoves are the most common solid-fuel burning devices used. Solid-fuel use, stove-operation behaviour and burning patterns vary within the township, however, the variation is insignificant. The majority of the residents have two burning events per winter day and a single event per summer day. Factors determining the choice of solid-fuel use are: (i) fuel availability (ii) demographics, and (iii) change of seasons. PM2.5 emission factors ranged from 6.8 g.kg-1 to 13.5 g.kg-1 of fuel burned. Fine particulate emission patterns change with burning patterns; high emissions are experienced during ignition and refuelling of the burning event. Fine particulate matter emitted from domestic burning per winter day in kwaDela Township ranges between 33.7 kg to 70.1 kg. Daily summer emissions range between 16.6 kg and 35.5 kg