This post is written by Holly M. Walder, first-year PhD student at Imperial College London, Dr Sarah Dack, specialist environmental public health scientist at the UK Health Security Agency, and Dr Ian S. Mudway, senior lecturer in environmental toxicology at Imperial College London.
The problem: Potentially unquantified risks to public health from the redevelopment of brownfield sites within densely populated urban areas.
Why it matters: Recent government planning policies prioritise the redevelopment of brownfield sites to provide new housing.
The solution: Early and active engagement of public health officials in strategic planning decisions.
Brownfield land are sites of former industrial use that are now derelict. Brownfields tend to be situated in deprived, urban areas where there are higher population densities, existing inequalities, and susceptibilities to poor health. This disparity between lower socioeconomic status and poor environmental health has been termed āenvironmental injusticeā. In these deprived areas, younger families and key workers urgently need affordable, suitable homes. As a result of this, the introduction of the planning policy āBuild Back Betterā by the UK government combined with the Brownfield Land Register (2017) has identified enough suitable brownfield land to build 1.3 million homes.
In October 2021, the UK government announced in its autumn budget that Ā£1.8bn ($2.4bn) will fund brownfield reclamation, with a further Ā£11.5bn ($15.4bn) towards building 180,000 affordable homes on 1,500 hectares of brownfield land. The redevelopment of brownfield land is often seen as a progressive planning policy, aimed at stimulating urban communities and economies, recycling underused land, and preserving green space in cities. However, concerns have been expressed about legacy pollutants at these sites and their impact on local populations, both during the process of site decontamination and construction, or over the long-term on residents living within newly built housing developments.
"As we press the accelerator on the redevelopment of these former industrial sites, can we be certain that the regulations, as they stand, remain fit for purpose."
Former manufactured gasworks
One of the UKās historical industries associated with brownfield sites are former manufactured gasworks. Former gasworks sites are numerous in the UK, with an estimate of over 4,000 in England, a considerable proportion of the total 21,000 brownfield sites estimated in 2020. They are also numerous worldwide, with thousands in the United States, and a significant number in Europe and many other industrialised countries. All former gasworks sites are unique in their history and site characterisation; some still retaining the distinctive, skeletal metal frames used to store the gas. During the 19th and 20th centuries, coal was burnt to produce gas for the lighting and heating of our homes. Other substances were also produced, for example, coal tar; a dark, thick, strong-smelling liquid used for road paving and shipbuilding, and coke; a pale, solid substance used as a āsmokeless fuelā in smelting industries.
Many of these sites were abandoned after the coal gas industries were shut down during the 1960s, leaving behind a buried toxic legacy, leaching into the surrounding soil, water, and air over the years. Now that brownfields are a target for housing developments, the developers are required to remove toxic substances and demonstrate the sites are safe by using policy-generated guidelines such as the UK Soil Guideline Values. Persistent substances, like coal tar, remain buried underground and can be enriched in carcinogenic, mutagenic and teratogenic compounds such as polycyclic aromatic hydrocarbons and heavy metals. The impact of these compounds is widely appreciated, and there are numerous findings on the increased cancer risks to former gas and coking workers.
These abandoned sites can therefore pose a considerable risk to neighbourhoods where the contaminants are exposed and require remediation. The regulations are clear on how to remediate contaminated land, but there are questions as to whether these remedialĀ processes have kept pace withĀ our evolving understanding of the long-term health impacts of low-level chemical exposures within the environment.Ā Simply put,Ā as we press the accelerator on the redevelopment of these former industrial sites, can we be certain that the regulations, as they stand, remain fit for purpose, or that there is good compliance with pre-existing legal frameworks? Within this context, it is imperative that emerging findings in environmental health science interface with policy to maintain an effective link between precaution and development.
"We must make sure that consideration of the publicās health isnāt sacrificed for urban renewal."
Working effectively with stakeholders
This dilemma is important for public servants because implementing national government policy at a local level can be challenging, especially in disadvantaged communities where there is often a lack of trust. Additionally, the redevelopment of these sites requires input from multiple public service sectors, in particular decisions from planning and public health. However, these separate departments are often not well aligned in the planning cycle and lack the capacity to check if sites are compliant with current land remediation guidelines. It is therefore essential that these departments work closely from an early stage in these projects, together with the developers and the local community to ensure transparency and compliance throughout. In this way, any potential impact on human health is minimised, both to the communities surrounding these sites during development, but also to the residents who will ultimately live there.
During remediation of some former gasworks, there have been numerous examples of local citizens noticing strong, chemical smells and other physical symptoms such as dizziness and nausea. These concerns have resulted in citizen-led groups campaigning for stricter regulations during remediation of gasworks to limit pollutant dispersal, promoting additional research on health risks, particularly on vulnerable groups, and calling for improved community engagement around the planning and strategy of new redevelopments. Clearly there is a public concern, but the failure to adequately address this has resultedĀ inĀ distrustĀ between communities, developers,Ā and localĀ government.
The problem highlights the growing tension between protecting the publicās health and economicĀ development. Therefore, it is important that scienceĀ actively plays a role to ensure that evidence, not opinions, drives decision-making. For example, new research is needed to characterise the emission of gases, volatile and semi-volatile organic compounds and toxicants associated with windblown dust from these sites across the full cycle of their development, from derelict land, through remediation to the building of new homes, and consideration of odours on mental health and as stressors, not just as toxic or carcinogenic compounds.
It is important to understandĀ the potential chemical risks associated with theseĀ sites and through careful engagement with the community and other stakeholders, bringĀ scientific evidenceĀ to the debate. Only then can modern, refined legislation and guidelines be created around the redevelopment of brownfield sites that satisfies both public, scientific, and economic interests. Brownfields, particularly former gasworks, are being remediated and re-used to produce cleaner and safer neighbourhoods and create the housing thatās needed, but we must make sure that consideration of the publicās health isnāt sacrificed for urban renewal.
Dr Ian S. Mudway and Holly M. Walder are part-funded by the NIHR Health Protection Research Unit Chemical Radiation Threats and Hazards, a partnership between the UK Health Security Agency and Imperial College London. Dr Sarah Dack is a full-time employee of UKHSA. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.
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