Benzene, a volatile organic compound (VOC) with widespread industrial applications, poses severe health risks to humans even at trace levels. Its genotoxic effects, which involve direct damage to cellular DNA and genetic material leading to mutations, are strongly linked to cancer and blood disorders, making its control a critical priority for workplace safety and environmental policy. Current air filtration technologies, prevalent in industrial and urban settings, rely on conventional methods that often fall short for capturing trace-levels of benzene, leaving a gap in effective protection against this carcinogen. Here, Professor Martin Schröder and Professor Sihai Yang, Department of Chemistry at The University of Manchester, explore how advanced materials science can break this technological barrier and support healthier air quality standards in high-risk environments.

• Benzene exposure, even at trace levels, is strongly linked to cancers and blood disorders, with current filtration technologies struggling to address low-concentration exposure risks.
• Research at The University of Manchester is developing new types of metal-organic framework (MOF) materials, offering cutting-edge solutions for efficient benzene removal.
• Policymakers are encouraged to support stringent air quality standards and incentivise the adoption of advanced MOF and related technologies using porous materials in workplace safety protocols.

A growing concern for public health

The prevalence of benzene in air, from sources such as fuel emissions, industrial processes and tobacco smoke means that exposure risks extend far beyond specific industries. Classified as a Group 1 carcinogen by the International Agency for Research on Cancer, benzene exposure is consistently linked to an increased risk of leukaemia and other cancers, making it a significant public health concern. The World Health Organization has not identified any safe level for benzene exposure, underscoring the urgency of addressing this issue.

The challenge of benzene exposure is particularly acute in urban environments and industrial zones where multiple emission sources combine to create complex exposure scenarios. Although regulatory bodies such as the US Occupational Safety and Health Administration (OSHA) and the UK Health and Safety Executive (HSE) set exposure limits for benzene, these measures alone are insufficient to mitigate fully the risks in workplaces and urban environments. Moreover, benzene can have both short-term and long-term health effects, emphasizing the pressing need for advanced and reliable solutions to effectively manage and reduce benzene exposure.

Conventional filtration systems fall short of capturing benzene, especially when it appears in low concentrations or under humid conditions. Systems such as activated carbons and zeolites lack the precision necessary to effectively address trace levels of this harmful compound. Advanced materials are essential to bridge this gap, yet development has been slow. The demand for effective, specialised filtration materials has intensified, driving research into innovative solutions capable of meeting the unique challenges of volatile organic compound (VOC) capture in real-world environments. 

What is MOF technology?

Metal-organic frameworks (MOFs) are a class of highly porous materials composed of metal ions bridged by organic molecules to form a robust, porous structure that acts as a sponge capable of trapping gases and pollutants. MOFs exhibit remarkable potential for environmental applications due to their unique ability to selectively capture specific molecules within their porous network. Unlike conventional materials such as activated carbon, MOFs offer the advantage of tunability. Their pore sizes and chemical properties can be engineered to target and capture pollutants like benzene with high precision.

Our recent research has pioneered a breakthrough in benzene adsorption with the development of MIL-125-Zn, a MOF designed with specifically engineered structural defects that significantly enhance its benzene capture efficiency. Testing reveals that MIL-125-Zn achieves a benzene adsorption rate of 7.63 mmol/g at low pressures and demonstrated the ability to reduce atmospheric benzene levels from 5 ppm to less than 0.5 ppm, surpassing the performance of state-of-the-art porous sorbents by a substantial margin.

Additionally, the material retains high efficiency over multiple cycles of benzene adsorption and benzene desorption and for sorbent reactivation, underscoring its durability and suitability for long-term use in industrial and environmental applications. This durability and effectiveness highlight this advanced material as a promising candidate for broader implementation in air quality management, where it could be integrated into purification systems to mitigate benzene exposure in high-risk areas.

Policy recommendations

Innovation in advanced materials, such as MOFs, offers powerful tools to tackle the challenge of removal of trace levels of benzene, and can drive the adoption of high-efficiency benzene removal in industries with high exposure risks. By promoting these technologies, regulators such as the UK’s cross-government Work and Health Unit can not only enforce improved workplace safety, but also address long-term health risks associated with benzene exposure, reducing the burden on the NHS by lowering benzene-related occupational health issues.

To fully capitalize on the promise of MOF technologies, it is essential that the Health and Safety Executive (HSE) facilitate the updating of workplace exposure limits (WELs) in EH40/2005, particularly regarding the current long-term exposure limit for benzene (1 ppm over an 8-hour total weight average reference period). Stricter benzene exposure thresholds aligned with the latest MOF capabilities will help mitigate carcinogenic risks and foster safer working environments. The integration of these MOF-based systems into best available technology standards would also create a clear pathway for industry adoption.

Government support is crucial to pave the way from research to widespread industrial adoption of MOF technology. Financial incentives like tax breaks and grants, especially for Small and Medium Enterprises (SMEs), would help ease financial barriers. Recognition programs and pilot projects could build momentum, while dedicated research centres and centres of excellence would offer critical resources and guidance for businesses transitioning to MOF technology.

Positioning the UK as a leader in MOF-based technology for air pollutant removal would strengthen public health and enhance the nation’s competitive edge in the global environmental solutions market. Policymakers should support the creation of a comprehensive framework that combines regulatory oversight, technical standards, and monitoring systems. This should include updated HSE workplace exposure regulations, British Standards Institution (BSI) technical standards for MOF manufacturing and implementation, environmental performance monitoring protocols, regular compliance auditing requirements, and industry-specific safety guidelines. This integrated approach will enable the UK to foster an ecosystem where MOF technology thrives, setting new standards in workplace safety, driving green technology growth, and supporting sustainable industrial practices.