“Experiments to dim the Sun will be approved within weeks” writes the Telegraph on 22nd April, 2025. Similar reports by GB News, Daily Mail, The Telegraph, The Guardian, and others outlining the plans and controversies. For example, The Guardian notes the experiments are controversial, with risks like altering weather patterns, while The Telegraph mentions specific techniques like marine cloud brightening.

THE NEWS: The UK government is set to approve outdoor experiments aimed at dimming sunlight to combat global warming, with funding of £50 million allocated by the Advanced Research and Invention Agency (ARIA). These experiments, expected to be greenlit within weeks, will involve small-scale, controlled field trials, such as injecting aerosols into the atmosphere or brightening clouds to reflect sunlight. The goal is to gather real-world data to assess the potential of solar geoengineering to prevent (supposedly) runaway climate change. These methods comes from observations like brighter clouds over shipping routes due to pollution and a 2014 Icelandic volcanic eruption that increased cloud reflectivity. However, geoengineering remains controversial, with concerns about unintended consequences like impacts on food production.

Quite remarkably, the Telegraph article does NOT address specific health consequences of aerosol chemicals used in solar geoengineering. However, it mentions that the planned experiments, funded by the UK’s Advanced Research and Invention Agency (ARIA), will use materials like sulphate aerosols and calcite (calcium carbonate) in small-scale, controlled outdoor trials.

Professor Mark Symes, the program director, emphasized that these experiments are designed to be safe, reversible, and avoid releasing toxic substances. Despite these assurances, the broader scientific literature and public discourse raise significant concerns about the potential health impacts of aerosol chemicals used in stratospheric aerosol injection (SAI) and similar solar geoengineering methods.

Below, I outline the potential health consequences based on available research, focusing on the chemicals mentioned (sulphates and calcium carbonate) and other commonly studied aerosols like aluminum oxide, while addressing uncertainties and controversies.

Potential Health Consequences of Aerosol Chemicals

1. Sulphate Aerosols (e.g., Sulphur Dioxide, SO₂, or Sulphuric Acid, H₂SO₄)
   Sulphate aerosols are the most studied for SAI, modeled after volcanic eruptions like Mount Pinatubo in 1991, which temporarily cooled the planet by injecting sulphur dioxide into the stratosphere.
   • Respiratory and Cardiovascular Effects: When sulphate aerosols eventually descend from the stratosphere to the troposphere (after 1-2 years), they can form fine particulate matter (PM2.5). Inhalation of PM2.5 is linked to respiratory issues (e.g., asthma, bronchitis, lung irritation) and cardiovascular problems (e.g., heart attacks, arrhythmias), particularly in vulnerable populations like children, the elderly, or those with preexisting conditions. A 2016 study in Environmental Health noted that global deployment of sulphate-based SAI could lead to widespread exposure, necessitating harmonized exposure limits to protect public health.
   • Acid Rain: Sulphur dioxide can react with water vapor to form sulphuric acid, contributing to acid rain. This can contaminate water sources, harm aquatic ecosystems, and indirectly affect human health by impacting agriculture and drinking water quality. Acid rain has the potential to damage forests and crops, though controlled experiments should be small enough NOT to cause these (however, this may lead to these concerns being “forgotten” or downplayed when going from small controlled experiments to deployment on scale).2
   • Ozone Depletion and UV Exposure: SAI with sulphates can deplete the stratospheric ozone layer, increasing ultraviolet (UV) radiation at the surface. This could elevate risks of skin cancer, cataracts, and immune system suppression. However, a 2023 study suggested that chemical feedbacks from SAI might improve air quality, potentially offsetting some UV-related mortality by reducing particulate pollution. The net health impact remains uncertain and depends on deployment scale and aerosol type.
   • Tropospheric Chemistry Changes: SAI can alter tropospheric oxidative capacity, affecting concentrations of greenhouse gases like methane and ozone. While this might improve air quality in some regions, it could worsen it in others, with unpredictable health outcomes. For example, reduced sunlight could lower photochemical smog but disrupt ecosystems reliant on consistent sunlight, indirectly affecting food security.
2. Calcium Carbonate (CaCO₃, “Chalk Dust”)
   • Calcium carbonate is being explored as a potentially safer alternative to sulphates, as it may cause less ozone depletion. The UK experiments plan to test calcite nanoparticles, as noted in the Telegraph article and other sources. (Nanoparticles? That does not sound like a great idea…)
   • “Tiny chalk particles” might lodge in the lungs, potentially causing inflammation or long-term damage, though this claim has not been studied in peer-reviewed studies.. The Environmental Health study cautioned that nanoparticle exposure from SAI could pose occupational and public health risks, particularly for workers handling these materials, but data on calcium carbonate’s specific effects are limited.
   • Environmental Deposition: Calcium carbonate is considered less reactive than sulphates, but its deposition could alter soil pH or water chemistry, potentially affecting agriculture or aquatic life. These changes could indirectly impact human health through food or water contamination, though such effects are speculative at the small scale of current experiments.
   • Lower Toxicity Profile: Compared to sulphates, calcium carbonate is generally regarded as less harmful, with fewer known risks like acid rain or ozone depletion. The Harvard Solar Geoengineering Research Program’s SCoPEx experiment, which planned to test calcium carbonate, emphasized its relative safety, though public backlash halted the trial. So… they could not proceed with the study in the US and therefore decided to run it in the UK? Who exactly is benefiting from this?
3. Aluminum Oxide (Al₂O₃, Alumina)
   • Although not mentioned in the Telegraph article, aluminum oxide has been proposed as an alternative SAI aerosol due to its high reflectivity and potential to minimize ozone loss.
   • Neurotoxicity Concerns: A 2022 BMJ article warned that aluminum oxide aerosols could increase global aluminum exposure, potentially contributing to neurodevelopmental toxicity. Studies have linked chronic aluminum exposure to brain aging, neurodegeneration, and higher aluminum levels in autism spectrum disorder brains, though causality remains unproven. The article argued that widespread SAI with alumina could threaten global mental health, particularly in developing countries, labeling it a “silent pandemic” of neurotoxicity.
   • Precipitation and Exposure: Aluminum particles could precipitate onto land and water, increasing human exposure through inhalation, ingestion, or skin contact. The long residence time of alumina in the stratosphere (1-2 years) means exposure could persist, amplifying risks over time.
   • Controversial. There is nothing controversial about wanting to avoid aluminium/aluminum. Doctors with PhDs in toxic metals recommend avoiding aluminium in all forms, because it is so very damaging to our health.
4. Other Proposed Aerosols (e.g., Titanium Dioxide, Diamond Dust)
   • Less commonly discussed aerosols like titanium dioxide or diamond dust have been proposed for SAI but are not part of the UK trials.
   • Titanium Dioxide: Used in some geoengineering models, it’s a potent light scatterer but can cause respiratory irritation and is classified as a possible carcinogen when inhaled in nanoparticle form. Long-term atmospheric effects are poorly studied.
   • Diamond Dust: Theoretically effective due to high reflectivity, it’s prohibitively expensive and lacks health impact studies. Its inclusion in research is mostly academic.

Broader Health and Environmental Concerns

• Vitamin D Deficiency: By reducing sunlight, SAI could decrease UVB rays needed for vitamin D synthesis, particularly in high-latitude regions like the UK or among darker-skinned populations. Low vitamin D levels are linked to bone disorders, weakened immunity, and mood disorders.
• Food Security and Ecosystem Disruption: SAI could alter precipitation patterns, potentially disrupting monsoons critical for agriculture in regions like Africa or Asia. Droughts or reduced crop yields could exacerbate malnutrition, indirectly affecting global health. The Telegraph article acknowledges concerns about shifting rains vital to food production, a point echoed by critics of geoengineering
• Termination Shock: If SAI is deployed and then abruptly stopped, rapid warming (“termination shock”) could occur, overwhelming health systems and ecosystems. This risk, while not immediate, underscores the need for long-term governance.
• Psychosocial Impacts: Public fear of “chemtrails” or atmospheric manipulation could erode trust in institutions, leading to social unrest issues. (And who could blame them?)

Critical Examination

While the UK’s experiments are framed as low-risk and scientifically necessary, the broader narrative around SAI raises red flags. The reliance on volcanic analogs oversimplifies SAI’s impacts, as human-controlled injections would involve sustained, global-scale operations with unpredictable chemical feedbacks. Claims of safety for materials like calcium carbonate are premature without long-term exposure studies, and sulphates’ known risks (e.g., ozone depletion, acid rain) suggest caution.

Why are these experiments run in the densely populated UK, when they were terminated in California, due to public outcry?

Conversely, some claim dismissing SAI outright ignores its potential to buy time against climate tipping points (assuming it is agreed these exist), as Symes argues. They claim that “the challenge lies in balancing urgent climate action with rigorous, transparent risk assessment”.

But is this true? The term “URGENCY” is a red flag here! Whenever something is pushed under the auspices of an emergency, BAD (unproven, untested and under-researched) options are implemented far too quickly with little regard for long-term negative consequences.

Damaging ozone layer, environment and human health under the guise of trying to fight “climate change” sounds like a crazy idea to me. There are better and less toxic ways…

ZOOM OUT for some PERSPECTIVE

If we zoom further out, the whole thing is totally crazy. As the Guardian reported in 2012, there had been a general “global dimming” in the world due to pollution, but some areas (notably Europe) had been recovering from it, achieving a kind of “brightening”, ostensibly as more and more industry had been shifting abroad during to economic cycles as well as our determination to race towards NetZero. As a result, more sun rays get through and we are told we cannot have that. So what? They will now dim the sun again: instead of having it dimmed by the pollution of “dirty industry”, this time they’ll manufacture chemicals and spray them into the atmosphere, losing out on all the potential health benefits of having less industrial activity on our island. If it sounds bonkers, it is because it actually is!

SOURCES

https://www.telegraph.co.uk/news/2025/04/22/experiments-to-dim-the-sun-get-green-light/

https://www.gbnews.com/science/science-news-latest-britain-approve-sun-dimming-experiments-climate-change

https://www.newsweek.com/experiment-dim-sun-uk-sparks-alarm-2063537

https://www.dailymail.co.uk/sciencetech/article-14638689/Experiments-dim-SUN-curb-global-warming.html

https://amp.theguardian.com/environment/2012/may/11/global-dimming-pollution