“Polycyclic aromatic hydrocarbons (PAHs) are primarily produced during incomplete combustion in transport, local heating systems, and industry. They are also released during food preparation, such as frying or grilling. A significant source is tobacco smoke. These substances are toxic and proven to be carcinogenic, which is why their concentrations are monitored in the air,” explains one of the study’s authors, Soňa Smetanová.
The study analysed urine samples from over a thousand volunteers across two time periods and various age groups: mothers and children from the DEMOCOPHES-CZ project (2011–2012), and children, adolescents, and young adults from the CELSPAC cohort (2019–2020). In addition to measured concentrations of PAH metabolites in urine, data were collected on participants’ place of residence, heating and cooking methods, diet, smoking habits, and other sociodemographic factors.
The most significant factors influencing exposure to PAHs were smoking, the energy source used for cooking (electricity/gas), certain types of food, place of residence (urban/rural), and the season – which relates to the type and intensity of heating.
“The study showed a significant decrease in PAH metabolites in urine between the two periods, both in children and adults. This reduction coincided with the implementation of the Air Protection Act in 2012, the anti-smoking law in 2017, and the boiler subsidy programme between 2014 and 2024,” adds Soňa Smetanová.
The main conclusion of the study is a positive one: the burden of polycyclic aromatic hydrocarbons in the Czech Republic is decreasing. It also highlights how legislative measures can directly and indirectly improve environmental quality – for example, by changing people’s behaviour (less smoking, switching to e-cigarettes, replacing old solid-fuel boilers with gas boilers or heat pumps).
And another piece of good news: each of us can reduce our own exposure to PAHs. This can be achieved by avoiding smoking, eating quality food prepared in a healthy way, and not burning solid fuels in low-quality stoves or boilers.
Learn more: https://www.nature.com/articles/s41370-025-00793-z
