Herbal cigarettes, widely sold in India and abroad as natural, tobacco-free and even therapeutic alternatives to conventional cigarettes, are not safer than regular tobacco cigarettes. They produce emissions that can be comparably or even more damaging as tobacco smoke.

These are the key findings of a new joint study by the  Indian Institute of Technology Gandhinagar (IITGN) and the University of Illinois Urbana-Champaign (UIUC), U.S.

The study compared emissions from two of India’s best-selling tobacco brands and four popular herbal varieties containing combinations of basil, clove, cinnamon, mint, green tea, water lily, and chamomile. Notably, two of the herbal brands utilised tendu (ebony) leaves as wrappers, identical to those used in bidis, India’s most widely consumed smoking product.

On the occasion of World No Tobacco Day, observed by the World Health Organization and other stakeholders, it is imperative to create awareness that Herbal Cigarettes Are Not Safer Than Tobacco. Each year on 31 May, WHO collaborates with governments, health organisations, civil society and youth to end the tobacco epidemic and secure a tobacco- and nicotine-free future for the next generation.

The findings were published in the Journal of Hazardous Materials  (https://doi.org/10.1016/j.jhazmat.2026.142424), a peer-reviewed, high-impact international journal that publishes research on generation, treatment, management and environmental impact of hazardous substances and pollutants. The paper was co-authored by Alok Kumar Thakur and Sameer Patel from IIT Gandhinagar and P.S. Ganesh Subramanian and Vishal Verma from the University of Illinois, Urbana-Champaign, US.

The research paper presents a comprehensive comparison of the physical, chemical, and oxidative properties of mainstream (firsthand) smoke from commercially available herbal and tobacco cigarettes in the Indian market.

Elaborating on the key findings, Prof. Sameer Patel, Assistant Professor, Department of Civil Engineering and Chemical Engineering, IITGN, and co-coordinator of the Dr Kiran C Patel Centre for Sustainable Development, IITGN, said, “Our findings challenge the widely held belief that tobacco-free means risk-free. Emissions from herbal cigarettes are comparable to or exceed those from tobacco cigarettes on nearly every metric we measured. Leaf-wrapped herbal variants turned out to be the most hazardous of all the samples tested.”

To isolate the emissions, each cigarette was combusted inside a sealed, automated two-chamber rig designed to replicate human inhalation rate. The cigarette emission was funnelled into real-time instruments, and filter samples were collected for physical and chemical characterisation of particles. As a proxy for the potential toxicity of emissions, the oxidative potential of the collected samples was quantified.

A key finding was that sub-500-nanometer particles were emitted at approximately 20 per cent higher concentrations in herbal smoke than in tobacco smoke. These fine particles are increasingly linked to cardiovascular and respiratory disease.

The team also measured a property called ‘Oxidative Potential’ (OP), which quantifies the smoke’s capacity to generate reactive oxygen species, aggressive molecules that drive inflammation, lung tissue remodelling, and the vascular changes underlying heart disease. Particulate matter from herbal cigarettes recorded significantly higher OP than that from tobacco cigarettes.

Tendu-leaf-wrapped variants, in particular, showed OP roughly 49 per cent higher than paper-wrapped versions. Interestingly, chemical analysis revealed one herbal cigarette, filled with basil, had the highest lead concentration, despite being marketed as “chemical-free with 100% natural filler for a healthy lifestyle.”

Prof. Vishal Verma, research collaborator and an Associate Professor of Environmental Engineering, in the Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, U.S., added, “That finding is important because many consumers associate nicotine-free products with reduced harm.”

‘REGULATORY GAP’

The study also lays bare the regulatory gap problem surrounding herbal cigarettes. India’s Cigarettes and Other Tobacco Products Act, 2003 (COTPA) regulates tobacco products through warning labels, advertising restrictions, and public-smoking rules, but products marketed as tobacco-free often fall outside these frameworks. Comparable regulatory gaps exist in several other countries.

According to lead author Dr. Alok Kumar Thakur, several of the herbal cigarettes they tested were marketed with claims of relieving cough, improving sleep, or easing anxiety. “However, there is limited scientific evidence evaluating the emissions and toxicological impacts of these products,” he added.

Dr. Thakur completed his PhD at IITGN as a Prime Minister Research Fellow and is currently pursuing postdoctoral research at Colorado State University, U.S.

The researchers emphasise that the study does not make direct epidemiological claims about disease outcomes. Instead, it focuses on measurable properties of the emitted smoke particles and their potential biological reactivity.

“Combustion, fine particles, soot, trace metals, and the wrapper around them all matter more than what is written on the box,” said Dr. P.S. Ganesh Subramanian, currently a postdoctoral researcher at Washington University in St. Louis, U.S.

The paper’s findings coincide with the theme of World No Tobacco Day on May 31, “Unmasking the appeal: countering nicotine and tobacco addiction.”

With the herbal cigarette category potentially attracting younger consumers and first-time smokers using wellness-oriented language, there is an urgent need to develop frameworks to regulate the marketing of tobacco alternatives. This study adds to a growing body of scientific evidence that could help inform evidence-based regulation and public-health discussions around alternative smoking products.

ABOUT IIT GANDHINAGAR

Indian Institute of Technology Gandhinagar strives to offer the best undergraduate and graduate education in India with unmatched innovations in curriculum. Its undergraduate program emphasizes project-oriented learning, creativity, liberal arts, design, life sciences, and globalization. Nearly 40 percent of its undergraduate students receive study abroad or other international opportunities. Its 5-week immersive Foundation Program for incoming students underscores creativity, leadership, communication skills, ethics, social awareness, and physical activity. IITGN is committed to promoting excellence in science, technology, as well as the humanities, and social sciences, and to the development of rounded and nuanced minds.

IITGN was founded in 2008 and is located in Palaj, Gandhinagar, on the banks of Sabarmati River, in close proximity of an international airport and Ahmedabad, India’s only UNESCO World Heritage city. The IITGN campus is the first in the country to receive a 5-star rating from GRIHA and has won three HUDCO awards.

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