Reflected light microscopy can be valuable tool to study impurities in pellet fuels.Some lump charcoal and charcoal briquettes contain a wide range of impurities.Detected contaminants were biomass, coal, coke, metals, sand, plastic, and glass.Contamination often exceeded 1% by volume that has been established in standards.There are relationships between impurities and the emissions during grilling.
Numerous studies have been conducted to assess air pollution and human health risks arising from exposure to outdoor cooking, but limited standards have been implemented around the world to assure fuel quality. While charcoal briquettes and lumps are a popular fuel choice for grilling, almost no data specifying their properties are available to consumers. Because the properties of fuels affect the flue gases, it is critical to understand how the quality of grilling briquettes and lumps translates not only into the quality of the grilled food, but, even more importantly, how their emissions impact human safety and the environment.
The main purpose of this study is to investigate the impacts of the quality of charcoal briquettes and lumps on potentially harmful emissions during grilling. To analyze their quality, we used reflected light microscopy to identify a range of contaminants, including biomass, mineral matter, coal, coke, metal, rust, plastics, glues, and synthetic resins, in 74 commercially available products made in Poland, the United States of America, Ukraine, Germany, Belarus, the Czech Republic, and the Republic of South Africa. Our data show that majority of the products analyzed do not meet the existing quality standard EN 1860-2:2005 (E) of less than 1% contaminants, some of these products contain up to 26.6% of impurities.
The amount of contaminants correlates with particulate matter, as well as CO and CO2. The contribution of biomass is especially significant because it can be used to predict harmful particulate matter emissions during grilling. The relationship between the composition of charcoal briquettes and lump charcoal and their emissions is particularly strong during the first 15 to 20min after ignition (when emissions are the highest), therefore, this initial stage is especially unsafe to consumers, and staying away from the grill during this time is recommended.