Database: food_inspection_2
Question: Among the facilities that had undergone at least one inspection in 2010, how many of them have the most serious food safety issues?
SQL: SELECT COUNT(DISTINCT T2.license_no) FROM inspection AS T1 INNER JOIN establishment AS T2 ON T1.license_no = T2.license_no WHERE strftime('%Y', T1.inspection_date) = '2010' AND T2.risk_level = 3