Construction And Demolition: Understanding Their Pollution Impact

Construction and demolition projects have a significant impact on the environment, causing various types of pollution, including air, water, and noise pollution. The use of heavy machinery and vehicles, which often run on diesel fuel, releases pollutants such as carbon monoxide, carbon dioxide, nitrogen oxides, and hydrocarbons into the air. Additionally, the demolition process generates high levels of dust and particulate matter, which can remain suspended in the air and be inhaled, causing respiratory issues. Soil pollution is another concern, as contaminants released during construction activities can negatively affect plant and animal life and pose health risks to humans. Water pollution can occur when toxic substances or improperly disposed materials enter nearby water bodies, leading to potential health issues for humans and animals. Construction activities also contribute to climate change, with a significant share of global carbon emissions attributed to this sector. The extraction of raw materials and the life-cycle emissions of buildings further exacerbate the environmental impact of construction projects.

Air pollution from diesel engines and hazardous chemicals

Construction and demolition projects cause air pollution through the use of diesel engines and hazardous chemicals. Diesel engines power many of the vehicles and machinery used on construction sites, and their emissions contain a range of harmful pollutants, including particulate matter, nitrogen oxides (NOx), carbon monoxide, carbon dioxide, sulphur compounds, and hydrocarbons. This particulate matter, sometimes called soot, is created during the incomplete combustion of diesel fuel. It varies in size from coarse to fine to ultrafine particulates, which can penetrate the cells of the lungs and cause respiratory and cardiovascular illnesses and even premature death.

Nitrogen oxides (NOx) are a significant component of diesel exhaust, and they contribute to the formation of ground-level ozone, which irritates the respiratory system. NOx is also a precursor chemical to fine particulate matter, which is a major component of air pollution. In addition, diesel exhaust contains numerous organic compounds, including over 40 known carcinogens, such as polycyclic aromatic hydrocarbons, benzene, formaldehyde, and acetaldehyde. These chemicals have been linked to lung cancer and other adverse health effects, with evidence suggesting that exposure can lead to lung cancer induction and death.

The impact of diesel emissions on air quality and public health has led to efforts to reduce exposure and emissions. For example, the California Air Resources Board has implemented regulations to reduce diesel particulate matter, and the Ontario Government's Drive Clean Program requires heavy-duty diesel trucks to be tested annually for their exhaust's smoke density.

In addition to diesel emissions, hazardous chemicals used on construction sites can also contribute to air pollution. Asbestos, for example, is a dangerous form of construction waste that can cause serious respiratory health risks when inhaled as airborne fibres and dust during demolition. The Ministry of Labour's Construction Health and Safety Action Plan highlights the significance of this issue, with mesothelioma, lung cancer, and asbestosis being the top causes of fatal occupational disease claims in the construction sector. Therefore, an asbestos abatement plan is often necessary when renovating or demolishing older buildings to manage the risks associated with asbestos exposure.

Noise pollution from machinery, vehicles and debris

Construction and demolition sites are inherently noisy, with the use of heavy machinery, vehicles, and debris all contributing to high noise levels. This noise pollution can have significant impacts on both workers and the surrounding environment, including immediate and long-term health risks. Continuous noise in construction persists for an extended period, and it is often steady and unvarying, similar to a constant drone or hum. Examples include the humming of generators, the whir of excavators, and the rumble of cement mixers, which can lead to persistent background noise exposure that is harmful to workers over time.

Bulldozers, for instance, can produce noise levels of 100-110 dB, while cement mixers generate continuous noise of around 85-90 dB. Prolonged exposure to noise levels above 85 dB can result in permanent hearing damage, emphasizing the importance of implementing preventive and protective measures for workers and mitigating the impact on the environment. Noise from construction sites can also reverberate into surrounding areas, disrupting peace and impacting the quality of life of nearby residents.

Demolition sites, in particular, face challenges associated with noise, dust, and debris. High noise levels from machinery, lorries, auxiliary vehicles, and falling debris can pose serious health risks to workers and the surrounding community. Effective noise control measures are crucial to ensure compliance with occupational safety and community regulations. Strategies such as temporary noise barriers, acoustic screens, and regular maintenance of machinery can help absorb and deflect sound waves, reducing noise pollution.

In addition to noise pollution, construction and demolition activities contribute to air pollution through the release of diesel emissions, dust, and hazardous chemicals. Diesel-powered machinery and vehicles emit pollutants such as carbon monoxide, carbon dioxide, nitrogen oxides, and hydrocarbons. The movement of machines and vehicles, as well as the breaking up of construction waste, further increases dust and particle concentration in the air, which can be inhaled and detrimental to human health.

To mitigate these issues, it is essential to adopt good practices, such as monitoring air pollution and providing information on air quality. While the noise impact immediately disappears once the machinery or work is stopped, the reduction in air quality may persist even after the emitting source has been interrupted. Therefore, implementing precautionary measures to manage harmful waste and reduce air pollution is crucial to protect the health of site employees and nearby residents.

Water pollution from spills and hazardous materials

Water pollution is one of the main types of pollution caused by construction and demolition. Water pollution happens when toxic substances are released into water bodies such as rivers, lakes, and oceans. This pollution may be visible on the surface or deposited on the bed, or invisible to the human eye, such as chemicals that dissolve in water.

One source of water pollution from construction sites is fuel and chemical spillages. The use of plant machinery and vehicles means that there is often a requirement to store fuel on-site. Failure to site fuel tanks at appropriate points away from vehicle routes and access points can result in accidental spillages. Diesel spillages spread very rapidly, killing fish, plant life, and invertebrates in streams and rivers. Fuel and chemical spillages can also affect the potability of water and, in some cases, result in the regulator having to close abstraction points along a watercourse. Other chemicals present on construction sites, such as those used in the cement-making process and solvents, can also cause water pollution if they are accidentally released.

In addition to fuel and chemical spillages, silt pollution is another common source of water pollution on construction sites. Silt pollution often occurs when greenfield sites are stripped back for cut and fill operations in preparation for construction activities. This can result in waste being blown or washed into nearby streams and rivers. Forward planning and the implementation of water management procedures can reduce the risk of silt pollution.

The release of hydrocarbons and other site waste, such as litter or building materials, into water bodies can also cause water pollution. To mitigate the risks associated with fuel and chemical pollution, site staff should be trained in using spill kits and know how to respond in the event of a significant spillage. Site managers should receive specialist environmental training, and fuel and chemical storage tanks should be positioned away from watercourses, surface water drains, access points, and traffic routes.

Soil pollution from excavation and hazardous materials

Soil pollution is a significant concern in construction and demolition projects, particularly when dealing with contaminated land. Soil contamination occurs when the concentration of pollutants in the soil is higher than it would naturally be, due to human activities. Excavation and the use of hazardous materials can introduce or spread these pollutants, causing soil pollution.

One of the main causes of soil pollution in construction is the disturbance of historically contaminated land. In the past, waste materials such as metal cans, coal slags, and contaminated dredge spoil were used as backfill in low-lying urban areas. When construction projects involve excavation in these areas, they can expose and spread the contamination. For example, removing concrete or tarmac with low permeability can allow more infiltration into the contaminated materials below. Excavation can also increase the movement of contaminants, causing them to migrate deeper into the ground, especially through layers of low-permeability materials.

Another concern is rainwater passing through stockpiles of contaminated material, which can carry pollutants into the ground. Any water removed from excavations in contaminated ground may itself be contaminated and require treatment before disposal. Additionally, the removal of structures containing hazardous materials, such as oils, can lead to soil pollution if not properly managed.

The use of hazardous materials in construction and demolition can also contribute to soil pollution. Asbestos, for example, was commonly used in older buildings for fireproofing, insulation, and piping. During demolition works, asbestos fibres can be released, posing serious health risks to those exposed. Other hazardous materials, such as lead, mercury, and arsenic, can also be released during construction and demolition activities, contaminating the soil.

To address soil pollution from excavation and hazardous materials, it is crucial to implement preventative measures. This includes conducting thorough site investigations to identify potential contamination, developing remediation plans, and ensuring proper waste management and disposal procedures. Environmental contractors can assist with the necessary equipment and vehicles for transporting and treating contaminated materials. Biological, chemical, and physical methods are available for treating contaminated soil, such as biopiles, soil stabilisation, soil washing, and thermal treatment.

Dust pollution from demolition and land clearing

Construction, demolition, and land-clearing activities can generate significant dust pollution, which is a major concern for human health and the environment. This dust is composed of particulate matter, including small (PM2.5) and large (PM10) particles, which can have detrimental health effects. The dust is released into the air during the demolition and land-clearing processes, spreading beyond the site and settling on nearby roads, properties, and ambient air.

The health risks associated with exposure to particle pollution are significant, including potential cardiovascular and respiratory issues. Health effects may include cardiac arrhythmias, heart attacks, asthma attacks, and bronchitis. The dust may contain harmful substances such as lead, asbestos, and other heavy metals, further exacerbating the health and environmental risks.

Regulatory requirements for dust control during demolition and land-clearing operations vary and may include local, county, state, and federal regulations. It is crucial to work closely with environmental regulators to determine the necessary control measures. Best management practices (BMPs) and other mitigation strategies, such as dust suppression techniques, are essential to minimize dust emissions.

To minimize dust pollution from demolition and land-clearing activities, several control measures can be implemented. These include the use of water or chemicals to control dust, applying asphalt, oil, or suitable chemicals on surfaces that create airborne dust, and installing hoods, fans, and fabric filters to enclose and vent dust-generating operations. Proper management of stormwater runoff is also crucial to prevent the release of pollutants from the site.

Additionally, environmental monitoring is recommended to assess air quality and ensure compliance with environmental impact assessments and legislation. While the dust pollution from demolition and land-clearing activities is temporary, it can have cumulative effects on air quality, especially for larger projects. Therefore, adopting good practices to reduce inconvenience to citizens and the environment is essential.

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