STEL: allowable concentration for short-time contact.

TWA, like concentration, is a physical index, indicating the measurement of chemical gas concentration in a certain period of time. TWA means that this average concentration is calculated by the contact time of chemicals with different concentrations in a specific period. In this way, different (higher and lower) exposure concentration values are averaged within one day or one week.

Application in futures;

On the one hand, if the futures price is higher than the weighted average price, the latter is moving up slowly or quickly, which means that the market situation will easily rise, but it is difficult to fall or continue to improve. On the contrary, if the futures price is lower than the weighted average price, the latter will move down slowly or quickly, which means that the market situation will be easy to fall but difficult to rise or continue to fade.

On the other hand, if the futures price is higher than the weighted average price, the latter is running in a narrow range or moving down. In other words, the market will slow down or turn around. On the contrary, if the futures price is lower than the weighted average price, the latter will run in a narrow range or upward, which means that the market situation will slow down the decline or turn around and pick up.