Abstract:   Based on the difference of indoor and outdoor O₃ concentration, using city-specific exposure factors, the paper found that 44400 and 137237 cases of all-cause mortality in 337 cities in China in 2020 could be attributed to short-term and long-term exposure to O₃ pollution, respectively. The corresponding economic losses were 237.5 billion yuan and 736.7 billion yuan, accounting for 0.23% and 0.73% of the GDP in that year, the short-term effect of O₃ pollution cannot be ignored. After setting more stringent indoor and outdoor air quality standards, this paper find that ① the current indoor air quality standards (160 μg/m³、112 μg/m³) cannot bring health benefits, When the daily indoor O₃ concentration in cities meets the standard of 60, 40, 30, 20 and 10 μg/m³, the total avoidable mortality is 90, 3931, 16191, 48861 and 85584 cases, and the corresponding avoidable economic losses are 7, 255, 971, 2787 and 468.1 billion yuan. ② When the daily outdoor O₃ concentration in cities meets the standard of 160, 100, 80, 70 and 60 μg/m³, the total avoidable mortality is 6044, 46090, 78888, 100160 and 124649 cases, and the corresponding avoidable economic losses are 355, 2548, 4298, 5420 and 670 billion yuan. Since the generation of O₃ involves precursor pollutants, it is more difficult to reduce the O₃ concentration than PM_2.5. The results show that reducing indoor O₃ concentration can effectively reduce ozone-related health effects and economic losses.