Thai Expert Warns Plastic Car Covers Pose Mold, Float Risks

BANGKOK — A Thai biology lecturer has warned motorists against leaving their cars wrapped in giant plastic bags for extended periods to protect them from floodwater, saying the method could lead to mold growth and even cause vehicles to float away. Assoc. Prof. Dr. Jessada Denduangboripant, a lecturer in the Department of Biology at Chulalongkorn University, issued the warning on his Facebook page, Jessada Denduangboripant, after images of large plastic covers designed to seal entire vehicles from floodwater circulated online. Jessada said such covers may be considered an emergency option for people who cannot move their vehicles to higher ground before flooding. However, he urged motorists not to leave cars sealed inside the covers for too long. Trapped moisture can cause mold According to Jessada, similar plastic covers were used during Thailand’s major floods in 2011. Some vehicle owners later found extensive mold growing inside their cars after they were left sealed for several days. The problem occurs because the plastic cover traps air and moisture around the vehicle. With little or no ventilation, moisture can accumulate and create conditions favorable for mold to grow. Mold can spread across seats, steering wheels and other fabric or interior surfaces, potentially causing extensive damage. Cars can float away Jessada also highlighted a less obvious risk: a plastic-covered vehicle can potentially float. Although cars are heavy, the air trapped inside a large waterproof cover can provide enough buoyancy for the covered vehicle to move with floodwater. In strong currents, a car could potentially drift away from its parking area and collide with other vehicles or objects. For that reason, he said the method is more suitable for vehicles parked inside a property where the cover can be securely anchored. Anyone who chooses to use such a cover should take measures to prevent it from floating away, he said. If the cover is punctured or torn after hitting another object, floodwater could quickly enter and reach the vehicle. Moving to higher ground remains the preferred option Jessada advised motorists who have enough time to prioritize moving their vehicles to higher ground rather than relying on a giant plastic cover. “If it is not necessary or a genuine emergency, don’t use this type of car cover,” he warned. For those who have no alternative and decide to use one, Jessada suggested securing or weighting the cover to prevent it from floating. He also suggested placing moisture-absorbing products inside the enclosed area to reduce humidity. The warning comes as giant vehicle-sized plastic flood covers have been promoted online as an emergency measure for motorists preparing for flooding. Jessada stressed that while such covers may prevent floodwater from directly reaching a vehicle, they do not eliminate the risks associated with prolonged moisture exposure or the buoyancy created by trapped air.