Ensuring Safe Indoor Air Quality in Historic Crypts: A Case Study of Northwood Cemetery

Sysco Environmental Ltd conducted an in-depth indoor air quality assessment at a historic crypt site under Northwood Cemetery in London. Our objective was to evaluate the air quality within the catacombs and identify any significant sources of contaminants that might pose risks to staff and visitors.
 
Northwood Cemetery in London is a historical gem, rich with heritage and significance. Located on the elevated part of the cemetery grounds, the site features a partially destroyed former chapel that once stood as a prominent structure. Beneath this chapel lies a network of catacombs, an intriguing aspect of the cemetery that adds to its historic allure.
 
The catacombs at Northwood Cemetery consist of 95 individual crypts constructed to serve as the final resting place for many. These crypts are located on a single level and are divided into six sections, accessible via a staircase at the side of the building. Positioned approximately 8-10 metres below the ground level. Despite their age and the partial destruction of the chapel above, the catacombs remain a significant part of Northwood Cemetery's history. The site is carefully maintained, with scaffolding structures in place to prevent water ingress and protect the integrity of the underground tombs.
 
Crypts like these were constructed for many purposes such as the belief that being buried in sacred ground, particularly close to martyrs and saints, would ensure their place in the resurrection. Historically, crypt burials were often reserved for the wealthy and influential. Noble families, high-ranking clergy, and notable community members could afford the cost associated with crypt construction and maintenance. Other more practical reasons were associated with the high population density in cities where burial space was at a premium. Catacombs, being underground, allowed for multiple layers of burials, effectively using space that was otherwise unavailable. They also served as communal burial sites where families could be interred together. This practice reinforced familial bonds even in death and allowed for easier visits by descendants.

 Air Quality Sampling and Analysis Methodology

 
In our assessment of underground crypts, we targeted a range of contaminants to ensure a comprehensive evaluation of indoor air quality and potential health risks. Prior to the field investigation, we conducted a thorough desktop study to identify relevant contaminants that could aid our investigation methods. This preliminary research ensured that our sampling strategy was both thorough and targeted.
 
We collected samples for volatile organic compounds (VOCs), formaldehyde, hydrogen sulphide, carbon dioxide, carbon monoxide, asbestos, other fibres, heavy metals, ionising radiation, radon gas, and fungal spores. These contaminants were chosen for their potential health impacts and relevance to the unique environment of underground crypts.

Findings from Indoor Air Quality Monitoring

 
Our comprehensive assessment of the underground crypts found that all targeted contaminants were within safe limits. VOCs were detected at low concentrations, well below occupational exposure limits. Formaldehyde and hydrogen sulphide were not detected above the analytical method's detection limit, indicating no significant risk from these gases. Carbon dioxide levels were consistent with natural background concentrations, and carbon monoxide was not detected, showing no immediate risk. Asbestos and other fibres were present at very low concentrations, far below clearance limits for residential properties. Heavy metals such as lead, arsenic, and mercury were found in floor dust but at non-hazardous levels. There were no significant sources of ionising radiation or radon gas. Although elevated concentrations of fungal spores were found, they do not pose a significant health risk to staff or visitors. Overall, the findings confirmed that the areas are safe to enter and work in.
 
Maintaining good indoor air quality involves monitoring a variety of contaminants, including VOCs, formaldehyde, carbon dioxide, asbestos fibres, heavy metals, and biological agents such as moulds and bacteria. Regular assessments and implementing effective control measures are essential to ensure a safe environment.

Potential Exposure Risks in Underground Crypts

 
Underground areas such as crypts pose several potential exposure risks, including poor air quality due to limited ventilation, which can lead to the accumulation of various gases such as carbon dioxide and VOCs, potentially causing respiratory issues or other health problems. Dust containing heavy metals such as lead, arsenic, and mercury can accumulate on surfaces, and inhalation or ingestion of these metals can lead to various health issues, including neurological damage and organ toxicity. Naturally occurring radioactive materials, such as radon gas, can accumulate in underground areas, with long-term exposure to high levels increasing the risk of lung cancer. Bacteria and other microbial contaminants can thrive in damp, poorly ventilated environments, potentially leading to infections and other health issues. Additionally, physical hazards such as unstable structures, low ceilings, and uneven floors can increase the risk of injury. Overall, thorough monitoring and control measures are essential to mitigate these risks and ensure the safety of individuals entering and working in underground areas like crypts.