Every time we exhale, we release thousands of different compounds along with the air. These include more than 3,000 volatile molecules, as well as a liquid component consisting of water vapor and tiny droplets, and a fraction of solid particles. Together, these elements provide a true chemical “snapshot” of what is happening inside our lungs and, more broadly, throughout our body.
Particularly valuable is the so-called alveolar fraction of breath, which originates from the deepest regions of the lungs. Because it is directly involved in gas exchange with the bloodstream, it reflects what the body has recently absorbed.
It is now recognized that respiration not only serves the function of indicating the health of the lungs, but can also serve as an indicator of chemical substances to which a person has been exposed through ambient air, ingested food, or direct contact with the skin.
This evidence emerges from the review published in 2024 by Bakali et al. in Trends in Analytical Chemistry, which summarizes the current state of the art in breath analysis as a tool for assessing environmental and occupational exposures.
The study’s findings substantiate the presence of quantifiable traces of pollutants to which individuals have been exposed, along with their metabolic by-products and biomarkers indicative of inflammation and physiological stress.
Some Practical Examples
• Athletes and cyclists training in traffic show traces of vehicle exhaust-related compounds in their breath, along with markers of inflammation associated with air pollution.
• Agricultural workers may exhibit residues of pesticides or signs of exposure to dust and bioaerosols originating from livestock facilities and composting environments.
• Firefighters show combustion-related compounds in their breath, sometimes even while using respiratory protective equipment, demonstrating that certain substances can enter the body through the skin.
• Swimmers exhale compounds derived from chlorine used in swimming pools.
• Researchers have even detected microplastics in exhaled breath, raising new questions about everyday exposure to these contaminants.
Why It Matters
Understanding what actually enters the body—not just what is present in the surrounding environment—makes it possible to assess health risks more accurately.
Information obtained through breath analysis can contribute to improved prevention strategies, support the design of safer workplaces, optimize ventilation systems, and promote more informed decision-making in areas affected by environmental pollution.
Although this field is still evolving, its prospects are extremely promising, and the first practical applications are already becoming a reality.
Studies are also underway in Italy. The Mistral Sampler, the device developed and manufactured by Predict for exhaled breath sampling, is currently being used in an occupational medicine project at the Military Hospital Center of Milan. The objective is to assess workers’ exposure to Volatile Organic Compounds (VOCs) present in professional environments.
Our breath does more than keep us alive—it may also become a valuable tool for protecting our health.
