1.The influence of altitude
     Since the atmospheric pressure is low in a high-altitude environment, discharge is very easy to occur, and the arc is thick. After the AC crosses zero, the circuit is very prone to discharge, and the arc is easy to re-ignite and is difficult to extinguish. Therefore, the insulation of power transmission and transformation equipment operating at high altitude and low pressure should be strengthened. Its influence must be fully considered when calculating insulation coordination, and the pollution lightning voltage should be appropriately increased. Generally, when the altitude is above 3000 m, the pollution voltage value should be considered to be increased by about 25% accordingly.
2. Effects of ice and snow covering on insulators
     Ice coating and snow coating of insulators have different effects on pollution lightning voltage. After experimental research by relevant scientific research departments, when insulators are first contaminated and then frozen, under the same salt density, the pollution lightning voltage will be lower whether in the frozen state or in the melting state. It can be improved if the withstand voltage of the ice remains unchanged when it is fully melted. Under normal circumstances, ice and snow in the air are often contaminated and then freeze on the insulator. At this time, its withstand voltage value is the lowest and flashover accidents are prone to occur. At present, countries around the world are paying great attention to the impact of high altitude and heavy ice areas on the electrical strength of insulators, and are actively carrying out research work.
3. Impact of acid rain and acid fog
     Due to different geographical environments, air pollution causes acid rain and acid fog to varying degrees in some areas. Since the conductivity of acidic pollution increases with the decrease of pH value, the flashover voltage of insulators is greatly reduced. With the acceleration of industrialization, the situation of power grids affected by air pollution has become more severe. Therefore, environmental awareness must be raised, law enforcement efforts must be strengthened, and technical measures must be taken to strengthen the management of power transmission and transformation equipment to avoid flashover accidents.