Planes have been found to harbour all kinds of bacteria and dirt.
Flight attendants have revealed that everything from hot drinks to tray tables breed all sorts of filth that could make you ill.
However, the circulated air can also cause problems for frequent travellers who are returning from a foreign country.
It is especially true for one dangerous disease.
Dengue fever outbreaks have increased in the past decade
Beijing Normal University discovered that dengue fever outbreaks have increased in the past decade and could have been caused by this.
Researchers Huaiyu Tian and Bing Xu of the scientific study PLOS Neglected Tropical Diseases were assisted by the University of Oxfordshire and found that three of the strains of Dengue were heavily linked to air travel.
The study analysed the spread of dengue fever across Asia from 1956 to 2015, as well as how they could be transported such as air travel and migration.
Air travel was found to be the main culprit, with Thailand and India spreading it through air transport the worst.
The research states: “Future trends in global mobility could potentially accelerate the appearance and diffusion of DENV worldwide.
“Prevention and control of dengue epidemics requires a better understanding of its mode of geographic dissemination, especially for countries in the tropics.”
There is no vaccine for the illness, which is spread through mosquitos.
Whilst many who suffer from the infection will recover within a few weeks with rest and fluids, some can go on to develop dengue hemorrhagic fever which can cause organ damage and severe bleeding.
It can be carried by the Asian Tiger mosquito, which was spotted earlier last year in Kent.
The eggs found were located near the M20, leading to experts believing they were brought by lorries from abroad.
Whilst it has since been exterminated, it shows how easily the virus could be brought to the UK.