Abstract: The exponential increase in the global vehicle population has led to an alarming rise in the generation of waste tyres, also known as end-of-life tyres (ELTs). Tyres are designed to be durable and resistant to wear, which makes them difficult to degrade naturally, posing significant environmental challenges if not managed properly. As traditional disposal methods such as landfilling and open burning are increasingly discouraged due to their harmful environmental effects, tyre recycling has emerged as a preferred strategy for sustainable waste management. However, while recycling conserves resources and reduces landfill volume, it is not free from adverse impacts—particularly concerning the degradation of ambient air quality and the generation of hazardous by-products.

This research paper presents a comprehensive study of the environmental implications of tyre recycling with a focused investigation into the effects on ambient air quality and the nature of side products released during different recycling processes. Field data were collected from three distinct types of tyre recycling facilities in India employing mechanical shredding, cryogenic grinding, and pyrolysis technologies. Using a combination of on-site air sampling, laboratory-based chemical analysis, and data modeling, we examined key pollutants such as particulate matter (PM2.5 and PM10), volatile

organic compounds (VOCs), sulfur oxides (SOx), nitrogen oxides (NOx), and polycyclic aromatic hydrocarbons (PAHs). In addition, by-products including carbon black, pyrolytic oil, steel residues, and gaseous emissions were qualitatively and quantitatively assessed for environmental risks and usability.

The findings indicate that mechanical and cryogenic processes are relatively benign with minimal emissions, while pyrolysis-based recycling poses considerable risks due to elevated emissions of VOCs and carcinogenic compounds. Specifically, pyrolysis operations recorded PM2.5 and PM10 levels exceeding National Ambient Air Quality Standards (NAAQS) by 65–90%, and VOC concentrations that surpassed WHO guidelines. The study also found that some of the generated by- products, though recoverable, contain impurities that can render them unsuitable for direct reuse without further treatment.

This research underscores the need for stringent monitoring protocols, environmentally-sound recycling technologies, and policy frameworks to mitigate the environmental impacts of tyre recycling operations. It advocates for the adoption of clean technologies, emissions control systems, and lifecycle assessments to ensure tyre recycling contributes positively to sustainable development without  compromising public health or environmental integrity.

Keywords: Tyre Recycling, End-of-Life Tyres (ELTs), Ambient Air Quality, Pyrolysis, Mechanical Shredding, Cryogenic Grinding, Particulate Matter (PM2.5, PM10), Volatile Organic Compounds (VOCs), Polycyclic Aromatic Hydrocarbons (PAHs), Carbon Black, Pyrolytic Oil, Environmental Impact, Recycling Emissions, Sustainable Waste Management, Airborne Toxins.