HK 1-hour Air Quality objectives for various air pollutants Air AQ AQ US AQ Pollutants ObjectivesObjectives Standards (ug/m3)(ppm) (ppm) Carbon 30000 262 35 mono×ide Sulfur 262 0.306 0.503 dioxide Nitrogen 35 0.159 005b dioxide Ozone 800 0.122 0.12 a:3-hr standard, b, annual arithmetic meanHK 1-hour Air Quality Objectives for various air pollutants Air Pollutants AQ Objectives (mg/m3) AQ Objectives (ppm) US AQ Standards (ppm) Carbon monoxide 30000 26.2 35 Sulfur dioxide 26.2 0.306 0.50a Nitrogen dioxide 35 0.159 0.05 b Ozone 800 0.122 0.12 a : 3-hr standard, b : annual arithmetic mean