In the heat of a warming world, public fountains have become the crown jewels of urban cooling and interactive play. With over 100,000 installations worldwide attracting 3 billion visitors annually, these features are more than just aesthetic landmarks—they are critical hubs of human activity. However, a new editorial published in Carbon Research warns that the mist we walk through might be carrying more than just a refreshing chill.
Professor Xiaohui Liu, from the Key Laboratory of Marine Environment and Ecology (Ministry of Education) and the College of Environmental Science and Engineering at the Ocean University of China, is spotlighting a silent public health risk. The editorial argues that while fountains provide relief from the "urban heat island" effect, they also serve as efficient engines for aerosolizing pathogens and toxic chemicals.
As water-saving policies encourage the use of reclaimed water and rainwater in these systems, the chemical and biological complexity of fountain water has skyrocketed. "This is a cross-media threat," notes Professor Xiaohui Liu. "Pollutants don't just stay in the water; they are launched into the air we breathe, often in concentrations far higher than what we find in the liquid source."
The Aerosol Effect: A Direct Route to the Lungs
The editorial details how high-pressure systems transform fountain water into microdroplets and aerosols. This transition is not a simple dilution. Instead, harmful substances can become enriched during the atomization process:
- The Pathogen Payload: Reclaimed water used in fountains can harbor Legionella—the bacteria responsible for pneumonia clusters—and E. coli. Recent outbreaks, such as the 2025 Legionnaires' crisis in New York, underscore how easily contaminated aerosols can travel through urban corridors.
- Chemical Concentration: Studies suggest that certain toxic compounds, like perfluoroalkyl acids, can reach concentrations in the air that are five orders of magnitude higher than in the raw water.
- Sunlight and Heat: In the peak of summer, strong sunlight and wind can cause these airborne contaminants to undergo secondary transformations, creating even more toxic pollutants that are easily inhaled.
Vulnerable Populations at Risk
Of the 3 billion people who visit fountains every year, an estimated 30% are children. Because children have higher inhalation rates relative to their body mass and are more likely to have direct dermal contact or accidental ingestion, they represent the most "at-risk" group for fountain-related illnesses, ranging from dermatitis to severe respiratory immune responses.
The fountain market is currently growing at a rate of 3.5% annually. Without unified water quality standards or regular maintenance of aerosol safety, the risk of a large-scale public health emergency continues to climb.
A Call for Joint Action
Professor Xiaohui Liu and the team at the Ocean University of China are calling for immediate collaboration between research institutions, government bodies, and system operators. The editorial proposes a four-pillar strategy to safeguard the public:
- Regular Monitoring: Establishing strict water quality checks that account for both chemicals and pathogens.
- System Management: Improving the engineering of fountains to reduce unnecessary aerosolization.
- Health Warnings: Issuing clear public guidance when water quality levels fluctuate.
- Public Awareness: Educating citizens on the differences between decorative water and safe "play" water.
As cities continue to densify and heat up, the role of the fountain will only grow. This editorial serves as a vital reminder that for these features to be truly sustainable, they must be as safe as they are beautiful.
Corresponding Author:
Xiaohui Liu
Key Laboratory of Marine Environment and Ecology, Ministry of Education. College of Environmental Science and Engineering, Ocean University of China, Qingdao, China.
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Journal reference: Liu, X., Wang, R., Han, M. et al. Spotlight the public health risks of fountains. Carbon Res. 5, 10 (2026).
https://doi.org/10.1007/s44246-025-00252-2
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About Carbon Research
The journal Carbon Research is an international multidisciplinary platform for communicating advances in fundamental and applied research on natural and engineered carbonaceous materials that are associated with ecological and environmental functions, energy generation, and global change. It is a fully Open Access (OA) journal and the Article Publishing Charges (APC) are waived until Dec 31, 2025. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon functions around the world to deliver findings from this rapidly expanding field of science. The journal is currently indexed by Scopus and Ei Compendex, and as of June 2025, the dynamic CiteScore value is 15.4.
