CREATE TABLE table_2780146_6 (standard VARCHAR, pm__g_kwh_ VARCHAR)
SELECT COUNT(standard) FROM table_2780146_6 WHERE pm__g_kwh_ = "0.02"
PM 0.02 g/kWh ต่างกันกี่มาตรฐาน?
How many different standards have a PM of 0.02 g/kWh?