Low oxygen also occurs in the interior of fruits and tubers when the temperature is high. This situation is more common in storage. Stretching can be the consequence of low light levels. Excess light is rare but may occur with indoor plants exposed to sun light or plants grown in the shade and suddenly exposed to sun. Pollutants Cultural practices etc.
Most pollutants are gases.
Ethylene, ammonia, chlorine, and mercury vapors are all possible problems in closed areas like greenhouses and storage facilities. Un-vented heaters and problems with the heater's exhaust are very common in the greenhouse industry. Plants can be injured and killed by gases in the soil. Gases may be directly toxic or reduce oxygen to critically low levels. Natural gas is not toxic per se.