CNA – If you’ve heard about the passenger “who had diarrhoea all the way through the airplane” on a Delta Air Lines flight, we’ll bet you can almost smell the stench coming through your handheld device as you read the story.
Just how bad was the cabin situation? A woman, whose partner was on the flight, tweeted that the vanilla-scented disinfectant used on the mess only made it smell worse.
This wasn’t the only occasion when bad smells created bad experiences on planes.
There was the case of the two passengers who were kicked off an Air Canada flight from Las Vegas to Montreal when they complained that their seats had vomit residue and a foul smell. It was later revealed that a passenger on an earlier flight had vomited. The airline crew cleaned it up and tried to cover the smell with coffee grounds and perfume.
These two tales will surely have you praying that you won’t encounter anything of the sort the next time you’re on a plane, but is there really nothing you can do about the smells if you were in their shoes? We ask the experts.
PRESSURISED CABIN VS BUS, CAR OR MRT: WHICH WOULD SMELL WORSE?
If those nose-assaulting incidents were replicated on other modes of public transportation such as the bus, MRT or private car hire (who’s to say the seat you’re in hasn’t been vomited on or has traces of urine or faecal matter?), would they fare worse?
“Within the cabin, there is no source of fresh air or ventilation,” said chief executive of Science Centre Singapore Associate Professor Lim Tit Meng. “The air is recirculated, which means that if there is an odour that starts to dissipate at one end of the plane, it will eventually diffuse throughout the space with nowhere to escape.”
While air also circulates within a fairly confined space on a bus or train, fresh air is able to enter through the doors, which open and close regularly, said Associate Professor Lim, which means odours can diffuse less densely through the air.
Furthermore, “buses and the MRT generally have more open spaces and lower passenger density, which can disperse odours more effectively”, said lecturer Dr Heng Kiang Soon with Republic Polytechnic’s School of Applied Science
WHY DOES HUMAN WASTE SMELL SO BAD?
If you’ve had to clean up human waste before, be it vomit, faeces or urine, you’ll know the immense task and disgust it involves. Even after all the wiping, mopping, disinfecting and gagging, the stench may still linger like an angry bumped-off passenger.
Why does human waste smell so bad? The odour comes from the volatile organic compounds (VOCs) and gases produced when microorganisms such as the bacteria in the digestive and urinary tracts break down organic matters, said Dr Heng. “The specific odour can vary between individuals as there are factors such as diet, hydration status, overall health status and the types of bacteria in the digestive tract that can affect the composition and intensity of the odours,” he said.
For instance, faeces get their odour from sulfur compounds such as hydrogen sulfide. “It can produce a strong, unpleasant odour that is often described as smelling like rotten eggs or sewage-like,” said Dr Heng.
In fact, your stool can be smellier if you eat a lot of foods that contain sulfur compounds such as broccoli, cabbage and garlic, said Associate Professor Lim.
As for the stink of urine, the primary chemical responsible for the pungency is ammonia, which is produced when the body breaks down proteins, said Associate Professor Lim.
“Ammonia itself doesn’t typically smell like rotten eggs. Instead, it has a pungent, chemical-like odour that is often described as sharp or acrid.” And that smell can be intensified when you’re not well hydrated. “Higher levels of waste products in urine are associated with a stronger odour,” he said.
What about the distinctive smell of vomit? That rancid odour similar to sour milk is from the butyric acid in the digestive tract, said Dr Heng. Gut bacteria and partially digested food can further contribute to the unpleasant bouquet, added Associate Professor Lim.
If you’re unfortunate enough to walk into a lift after someone has cut the cheese, welcome to your personal hell of methane, hydrogen sulfide, ammonia and carbon dioxide. What you smell is what the farter eats as foods such as beans and onions release more gas when digested, said Dr Heng.
WHAT’S THE BEST WAY TO NEUTRALISE ODOURS?
One effective compound is white vinegar, said Associate Professor Lim. “Simply mix equal parts water and white vinegar, and use this solution to clean surfaces affected by urine, faeces or vomit.” Or try baking soda, he said. “Sprinkle it on the affected areas and allow it to sit for five to 10 minutes before wiping it down.” It is also essential to clean up any waste properly before attempting to neutralise lingering smells, he said.
Speaking of smells, why does the odour sometimes linger even after cleaning up the mess? That’s because there may still be VOC residues suspended in the air or stuck to the surfaces in the environment, said Dr Heng.
“To remove the residues, open the windows or use fans to improve ventilation in the house or washroom. You can also place activated charcoal to help absorb the odour, and use air fresheners or deodorants to mask it.”
WHAT CAN YOU DO ABOUT BAD SMELLS ON THE GO?
For an odour-free journey, keep travel-sized air fresheners or essential oil sprays (lemon or mint) in your bag. “Use discreetly if need be but we should be considerate that the scent from the spray can also potentially cause inconvenience or discomfort to others,” said Dr Heng.
If you’re wearing a mask on public transportation, apply a few drops of essential oil on your mask to deodorise the inhaled air, he said. “On buses, MRT or planes, we can use the adjustable air vents to direct airflow away from the odour source. In a car, we can open the windows to ventilate the interior.”
Associate Professor Lim suggested sucking on a mint to help mask odours and provide a more pleasant scent in your immediate surroundings.
“If your environment allows it, like in a plane, ask for a strong cup of coffee as the rich scent can function as a smell neutraliser.
“If you can’t eat and drink in your environment, try controlled breathing techniques or divert your attention to something else like reading or listening to music to temporarily ignore the smell,” said Associate Professor Lim. – Khoo Bee Khim
