Modern jetliners have an environmental control system (ECS) that manages the flow of cabin air. Outside air enters the engines and is compressed in the forward section, prior to the combustion section, ensuring no combustion products can enter the cabin. A portion of that compressed bleed air is used to pressurize the cabin. The ECS then recirculates some of that cabin air through HEPA filters, while the rest is directed to outflow valves, ensuring there is a constant supply of fresh, clean air coming into the cabin pressurization system at all times.It is possible for contaminants to enter the cabin through the air-supply system and through other means. Substances used in the maintenance and treatment of aircraft, including aviation engine oil, hydraulic fluid, cleaning compounds and de-icing fluids, can contaminate the ECS. While ground and flight crews, as well as passengers themselves can be sources of contaminants such as pesticides, bioeffluents, viruses, bacteria, allergens, and fungal spores.Possible sources of poor-quality cabin air include exposures related to normal operations of the aircraft:

• Ozone (O3)
• Carbon dioxide (passengers exhaling CO2)
• Carbon monoxide (CO - Jet exhaust fumes, Ambient airport air)
• Temperature
• Relative humidity
• Off-gassing from interior material and cleaning agents
• Bioeffluents
• Personal-care products
• Allergens
• Infectious or inflammatory agents
• Cabin pressure/partial pressure of oxygen
• Alcohol
• Formaldehyde
• Deicing fluid.
• Particulate Matter (Including dust which contains microbes).
• Dry ice used to keep food cold.
• Toilet fluid, leaked or spilled.
• Rain repellent fluid.
• Pyrethroid Pesticides
• Pre-existing illness—such as anemia, asthma, COPD, and coronary arterial disease—the stresses of flight could exacerbate symptoms.

Environmental Issues PresentationTo test air quality on a flight you're on, you can use a portable air pollution monitor, such as the Atmo Tube.If you are concerned about air quality in a plane you're operating or riding on, you might want to consider carrying a portable, disposable charcoal carbon active mask:https://youtu.be/2z-B6AC1xUc As our way to help you celebrate the New Year, we’re offering a huge discount on the Hamfist Trilogy!You can download the book in the e-book format of your choice at Smashwords, and use coupon code GJ73Z for a 50% discount.