In the greenhouse vegetable cultivation process, because of closed facilities, there is little exchange of convection inside and outside the air, and harmful gases such as ammonia, nitrous acid, carbon monoxide, sulfur dioxide, and chlorine are not emitted, which will jeopardize the growth and development of vegetables. Production management should pay attention to prevention. 1. Pay attention to ventilation. As long as the temperature is not very low, the air inlet should be opened every day. Generally, the air is ventilated for more than 50 minutes. Because the "ammonia" and "nitrification" reactions of soil fertilizers always release ammonia gas and nitrous acid gas, they must be ventilated to avoid excessive levels and harm the vegetables. Ventilation is best in the early morning or at night, and it can simultaneously discharge the indoor steam, reduce the air humidity in the facility, and help prevent the occurrence of diseases. If the outdoor temperature is too low, ventilation will cause a rapid decline in indoor temperature, ventilation should be properly reduced, but no ventilation is allowed, can be a once every 2 days, change the morning and night ventilation for afternoon ventilation, time can be less than 30 minutes. Every morning, test the dew on the shed film with a pH test paper. If it is alkaline, it indicates that ammonia gas is produced and the air must be released promptly. 2. Scientific fertilization. Before the organic fertilizer is applied into the sheds for 2-3 months, it should be added with water and wetted. After the accumulation, the plastic film shall be tightly covered and fully fermented and decomposed before being applied into the shed. It is forbidden to spread nitrogen fertilizers, such as urea, ammonium bicarbonate, ammonium sulfate, and diammonium, in the facilities. If such chemical fertilizers are applied to the soil, they cannot be dissolved and absorbed by the soil solution in time and volatile ammonia gas will harm the vegetables. Therefore, the use should be reduced as much as possible. If topdressing must be applied, it should be combined with watering. Fertilizer should be dissolved into an aqueous solution in advance, flushed with water to prevent ammonia from evaporating and harming the vegetables. 3. Pay attention to the film quality. Optional polyethylene plastic film or reliable quality PVC plastic film. 4. Safe heating. Furnace and flue design should be reasonable, installation must be closed, and high-quality low-sulfur coal should be used for fuel. Strengthen heat management to prevent smoking. When the indoor ignition warms up, it must be fully fired by open flame, and the burning time must be strictly controlled to prevent harmful gases such as carbon monoxide and sulfur dioxide from exceeding the standard to harm the vegetables. 5. symptomatic rescue. When symptoms of poisoning appear, they should find out the reasons. In addition to taking targeted measures, they should also take measures such as watering, fertilizing, and loosening the soil to prompt the affected plants to resume growth as soon as possible. Puyang Linshi Medical Supplies Co., Ltd. , https://www.linshimedicals.com