Landfill Air Pollution: A Hidden Health Hazard?

Landfills are a major source of air pollution, releasing methane, carbon dioxide, and volatile organic compounds (VOCs) into the atmosphere as waste decays. Methane, a highly flammable and explosive gas, is a significant contributor to climate change, with 84 times the heat-absorbing capacity of carbon dioxide. Landfills also emit toxic gases such as ammonia, sulfides, and benzene, which can cause respiratory issues, eye and throat irritation, headaches, nausea, and other health problems for nearby residents. The release of these gases contributes to air pollution and poses risks to human health and the environment.

Methane emissions

Landfills are a major source of air pollution, and methane emissions are a significant contributor to this problem. Methane (CH4) is a potent greenhouse gas that has a much higher capacity for absorbing heat from the sun than carbon dioxide (CO2). According to the latest Intergovernmental Panel on Climate Change (IPCC) assessment report (AR5), methane is at least 28 times more effective than CO2 at trapping heat in the atmosphere over a 100-year period.

Municipal solid waste (MSW) landfills are the third-largest source of human-related methane emissions in the United States, accounting for approximately 14.4% of these emissions in 2022. The methane emissions from MSW landfills are roughly equivalent to the greenhouse gas emissions from more than 24 million gasoline-powered passenger vehicles driven for a year or the CO2 emissions from over 13 million homes' energy use for a year. Food waste, which makes up about 24% of MSW, is a major contributor to landfill methane emissions due to its rapid decay rate. An estimated 58% of fugitive methane emissions from MSW landfills come from food waste.

Landfill gas (LFG) is a natural byproduct of the decomposition of organic material in landfills. LFG typically consists of about 50% methane and 50% carbon dioxide, along with small amounts of other gases. When MSW is first deposited in a landfill, it initially undergoes aerobic decomposition with little methane generation. However, within less than a year, anaerobic conditions are established, and methane-producing bacteria begin to decompose the waste and release methane.

To mitigate the impact of methane emissions from landfills, various control measures can be implemented. Landfills can install gas collection wells with perforated pipes that provide a path for the gas to move vertically to the surface instead of migrating laterally towards nearby structures. The collected gas can then be vented into the outdoor air, burned, passed through a filter, or used in energy recovery programs. Advanced treatment methods can also remove impurities and compress the LFG into a high-Btu gas suitable for vehicle fuel or injection into gas pipelines.

Carbon dioxide emissions

Landfills are a major source of air pollution, and carbon dioxide is one of the primary gases emitted by landfills, along with methane. The release of these gases has significant environmental and social impacts, contributing to climate change and creating smog if left uncontrolled.

Composition of Landfill Gas

Landfill gas (LFG) is a natural byproduct of the decomposition of organic material in landfills. This process is facilitated by bacteria, and the gases produced can vary depending on factors such as the type of waste, the age of the landfill, oxygen content, moisture, and temperature. LFG is primarily composed of methane and carbon dioxide, which together make up about 90-98% of the gas. The remaining 2-10% includes nitrogen, oxygen, ammonia, hydrogen sulfide, and other gases.

Carbon dioxide (CO2) emissions from landfills contribute to the greenhouse effect and climate change. While methane is a more potent greenhouse gas, carbon dioxide plays a significant role in trapping heat in the atmosphere. According to the latest Intergovernmental Panel on Climate Change (IPCC) assessment report (AR5), methane is 28 times more effective than CO2 at trapping heat over a 100-year period. However, the high proportion of carbon dioxide in LFG means that it still has a considerable impact on global warming.

Municipal solid waste (MSW) landfills are the third-largest source of human-related methane emissions in the United States, and they also contribute significantly to CO2 emissions. In 2016, the Environmental Protection Agency (EPA) estimated that implementing emissions guidelines for MSW landfills would reduce methane emissions by 290,000 metric tons per year, which is equivalent to reducing carbon dioxide emissions by more than 24 million metric tons annually over a 20-year timeframe.

Mitigation Strategies

To mitigate carbon dioxide and other emissions from landfills, several strategies can be employed:

• Capturing and Treating LFG: Instead of letting LFG escape into the atmosphere, it can be captured, converted, and used as a renewable energy source. This helps reduce odors, hazards, and the formation of local smog associated with LFG emissions. LFG energy projects also create jobs and generate revenue.
• Landfill Gas Collection Systems: These systems, which can be configured as vertical wells or horizontal trenches, collect LFG and direct it to a central point for processing and treatment.
• Advanced Treatment: LFG can undergo advanced treatment to remove additional impurities, including CO2, to produce a high-Btu gas that can be used for vehicle fuel or injected into natural gas pipelines.
• Recycling and Composting: By increasing recycling and composting practices, the amount of waste sent to landfills can be reduced, thereby decreasing LFG emissions.

Volatile organic compounds (VOCs)

Landfills are a source of VOCs, as organic waste is broken down by bacteria. The amount of VOCs produced depends on the type of waste, the age of the landfill, the oxygen content, the moisture level, and the temperature. Higher temperatures and moisture content will increase gas production.

The health effects of VOC exposure vary depending on the specific chemical, the level of exposure, and the length of time exposed. Some common symptoms of exposure to high levels of VOCs include eye, nose, and throat irritation, headaches, loss of coordination, nausea, and damage to the liver, kidneys, or central nervous system. Some VOCs are suspected or proven carcinogens.

To reduce exposure to VOCs, it is recommended to limit the use of products containing VOCs, increase ventilation, and dispose of unused chemicals properly.

In summary, volatile organic compounds (VOCs) are a group of chemicals that can have adverse health effects and contribute to air pollution. They are present in many household products and are released from landfills, with the amount depending on various factors. Reducing VOC exposure is important to minimize potential health risks.

Leachate

The risks of leachate generation can be mitigated by properly designed and engineered landfill sites, such as those constructed on geologically impermeable materials or sites that use impermeable liners made of geomembranes or engineered clay. The use of linings is now mandatory within the United States, Australia, and the European Union except where the waste is deemed inert. In addition, most toxic and difficult materials are now specifically excluded from landfilling.

The greatest environmental risks occur in the discharges from older sites constructed before modern engineering standards became mandatory, and also from sites in the developing world where modern standards have not been applied. There are also substantial risks from illegal sites and ad-hoc sites used by organisations outside the law to dispose of waste materials.

Odour

Landfills are a major source of odour emissions, which are caused by the gases produced when bacteria break down organic waste. The most common gases emitted by landfills are ammonia, sulfides, methane, and carbon dioxide, with ammonia and hydrogen sulfide being responsible for most of the odours. These gases can move through the soil and collect in nearby buildings, causing odours and potential health issues for the occupants.

The impact of landfill odours can be mitigated by implementing gas collection and control systems, such as those required by the Environmental Protection Agency in the United States. Homeowners can also take measures to reduce landfill gas entry into their homes, such as sealing cracks and improving ventilation.

Overall, landfill odours are a significant issue that can have negative impacts on the health and well-being of nearby communities. It is important to take measures to reduce these odours and their potential health effects.

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