25% of the population suffers from hay fever which is a figure that is increasing and therefore making this allergic reaction sadly quite common. But there's another condition, similar in symptoms, that could potentially be even more dangerous. Every single person that has walked on the moon has suffered from the same symptoms. Known as 'lunar dust hay fever,' this condition, which has affected every single American astronaut, is both intriguing and worrying. To understand more about this condition, the European Space Agency has brought together a group of scientists.Symptoms and side effectsClassic symptoms of hay fever include sneezing, stuffy nose, inflamed larynx and watery eyes. This can last for days before going away. Interestingly, this is also exactly what every astronaut that has walked on the moon has experienced when they returned from their space journey.It’s this similarity to the common hay fever that inspired Harrison Schmitt, an American astronaut who was part of the Apollo 17 mission in 1972, to coin the term 'lunar dust hay fever.' It’s only when the astronauts returned to Earth that the particles that were caught on their suits started to give them sore throats and watery eyes. This is when experts really started to question the toxicity of this moon dust. Could venturing into space actually be a danger to human health?To find out more about this and avoid a future where the well-being of other astronauts is affected, scientists from the ESA decided to launch a research program consulting experts from all around the world.Pulmonary physiologist from the University of California, Kim Prisk, explained that: We don’t know how bad this dust is. It all comes down to an effort to estimate the degree of risk involved for future missions.Long term health concernsFrom the research that has been done, this mysterious moon dust is so abrasive that it has been shown to eat away at layers of space boots and attack the hermetic seals on containers for samples on the Apollo. It is also known to leave behind a pungent smell similar to gunpowder.The silicates that it contains are particles that are normally found in areas around active volcanoes and so when it is inhaled, can lead to breathing difficulties and lung damage which has been observed in people that work in mines in these regions. On our planet’s natural satellite, there is six times less gravity than on Earth, which is what causes things to float around in space. Prisk adds that:Particles 50 times smaller than a human hair can hang around for months inside your lungs. The longer the particle stays, the greater the chance for toxic effects.In order to know more about the effects of moon dust, researchers on the ESA project will analyze a substitute matter that they've retrieved from a volcanic region in Germany. Hopefully, the research will also have an answer on how to protect the astronauts from this harmful dust.