By Rubina Obaid
ncreased use of biomass is making the situation counterproductive and weakens public confidence about the environmentally compatible sources. Low technological advancement in the combustion system is becoming the main cause of significant emission of particulate matter.
In order to reach climate neutrality targets countries are actively contributing to reduce carbon dioxide emission and switching towards biomass and seeking safe renewable energy sources to replace fossil fuels. Within the last decade on a small scale, residential sector is utilizing biomass for room heating and warm water supply and using various stoves and biomass combustion systems such as wood pellets, woodchips, logwood boiler, pellet stoves, and tiled stoves. However, the biomass heating system is still operated through conventional logwood stoves and boilers while modern technologies of combustion are yet to penetrate the market. Hence, low technological advancement in the combustion system is becoming the main cause of significant emission of PM (Particulate matter). These particulate matters are dominated by carbonaceous particles and is responsible for adverse health effects.
Increased use of biomass is making the situation counterproductive and weakens public confidence about the environmentally compatible sources. PM emission from biomass combustion is precisely categorized into coarse fly ashes and aerosols, coarse fly ashes cause less contribution that is up to 10wt% out of the total particulate emission. Further, due to its size that is comparably large makes it negligible in terms of causing adverse health effects. Whereas aerosols create fine particles with a diameter that is of <1µm, that is much more complex. These aerosols can further be categorized into inorganic and carbonaceous particles, while inorganic particles can be influenced by the type of fuel applied and carbonaceous aerosols can be reduced by using optimized combustion processes that are also known as burnout optimization
The adverse effects of particulate matter on human health are relevant in both urban and rural settings worldwide. Elevated level of particulate matter is particularly associated with the poor quality of air and causes detrimental health effects. According to the latest studies it has been found out that the smallest particles which are less than 2.5 diameters are highly toxic. Particulate Matter emission from Biomass PM1 are ultrafine particles that stimulate oxidative stress and inflammation in the lung following inhalation problems. There are several potential reasons for the rising level of particulate matter, mainly domestic wood burning in rural as well as urban areas where it is becoming part of the lifestyle. Also increased use of domestic burners without having any proper particulate filter and other alternatives for controlled emission, therefore conventional boilers and even energy-efficient wood stoves emit twice as much particulate matter as coal appliances.
Domestic combustion of wood and wood products plays a significant role in the atmospheric concentration of PM that becomes one of the main causes of stimulating pulmonary toxicity, premature mortality and cardiovascular diseases and children are more prone to get affected. Inhalable particulate matter that may reach the lower airways are mainly classified into three size fractions PM10, PM2.5 and PM1. Particles greater than 8µm remain in pharynx, larynx, and trachea whereas particles greater than 5µm reach only upper part of the bronchi where it gets removed in the process of mucociliary clearance and 50% of the particles which are less than 4µm diameter penetrate in the lower respiratory tract. Particles less than 2.5 µm reach to the alveoli and remain in the lung tissue and ultrafine particles less than 1 µm penetrate even deeper into the airways and enter the bloodstream and induce alveolar inflammation and become the major cause of acute episodes of respiratory diseases. The concentration of PM also plays important role in ambient toxicity, pointing to different diameters of particles as having a different roles for eliciting health effects.