Particulate emission from biomass combustion

Mixing dried human sewage sludge with pulverized coal is being evaluated as a way to reduce carbon dioxide emissions from traditionally coal-fired power plants, as well as to overcome sewage-disposal problems. Here we investigate the effects of inhaling particles emitted from the combustion of this mixture and find that these cause significantly more lung damage in mice than do particles from coal alone, probably because of their zinc content. Our findings indicate that the use of dried municipal sewage sludge as a 'green' (CO2-neutral) replacement fuel should be considered with caution.