user: Question: How many different standards have a PM of 0.02 g/kWh?
Columns: ['Standard', 'Date', 'CO (g/kWh)', 'NO x (g/kWh)', 'HC (g/kWh)', 'PM (g/kWh)']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Euro 0', '1988–1992', '12.3', '15.8', '2.6', 'none']
SQL:

assistant: SELECT COUNT("Standard") FROM "Table" WHERE "PM (g/kWh)" = '0.02';