Grilling and air pollution: how charcoal quality affects emissions

Abstract

Cooking with charcoal is widely popular worldwide. Several types of lump charcoal and charcoal briquettes are available on the market, presenting distinct characteristics based on raw materials and production methods. Charcoal quality can significantly impact combustion properties and pollutant emissions. This study aims to: (1) assess the qualitative characteristics of commercial lump charcoal and charcoal briquettes, (2) evaluate the emission factors (EFs) associated with their combustion, and (3) investigate how different characteristics of charcoal affect air pollutant emissions. Significant differences in quality were observed among the charcoal samples analyzed. Lump charcoal generally exhibited superior characteristics, including a higher carbon content (> 75% d.b.), fixed carbon (> 75% d.b.), heating value (> 29 MJ/kg), and fuel ratio (> 4.5). In contrast, charcoal briquettes showed higher levels of volatile matter (> 20% d.b.), ash (> 15% d.b.), and moisture content (> 6% w.b.). Furthermore, charcoal briquettes exhibited higher EFs for carbon monoxide (CO) (> 250 g/kg), volatile organic compounds (VOC) (> 1.5 g/kg), and total suspended particulates (TSP) (> 7.5 g/kg) than lump charcoal. Principal component analysis (PCA) demonstrated a strong influence of qualitative characteristics on emission factors. Volatile matter, ash yield, moisture, and nitrogen content were positively correlated with higher emissions, while carbon content, fixed carbon, and fuel ratio were negatively correlated. As lump charcoal aligns more closely with the latter parameters, it releases lower emissions than briquettes. Improving charcoal production techniques and reinforcing international standards are crucial to ensure product quality, reduce emissions, and minimize environmental and health risks.