Characterization of particles emitted by pizzerias burning wood and briquettes: a case study at Sao Paulo, Brazil

The burning of biomass in pizza ovens can be an important source of air pollution. Fine particulate matter represents one of the most aggressive pollutants to human health, besides the potential to interfere with global radiative balance. A study in real-world condition was performed in three pizzerias in Sao Paulo city. Two of the pizzerias used eucalyptus timber logs and one used wooden briquettes. The results from the three pizzerias revealed high average concentrations of PM2.5: 6171.2 μg/m3 at the exit of the chimney and 68.2 μg/m3 in indoor areas. The burning of briquette revealed lower concentrations of PM2.5. BC represented approximately 20% and 30% of the PM2.5 mass concentration in indoor and at chimney exhaust, respectively. Among the trace elements, potassium, chlorine and sulphur were the most prevalent in terms of concentration. Scanning electron microscopy (SEM) analysis revealed particles with an individual and spherical morphology, i.e. the conglomeration of spherical particles, flattened particles in the formation of fibres, the overlapping of layers and the clustering of particles with sponge-like qualities. The average emission factors for PM2.5 and BC due to the burning of logs were 0.38 g/kg and 0.23 g/kg, respectively. The total emissions of PM2.5 and BC were 116.73 t/year and 70.65 t/year, respectively, in the burning of timber logs.