Beijing saw better air quality and more "good air" days in 2017, an official report said today, even as the Chinese capital, which bore the brunt of heavy air pollution for years, continues to be shrouded by bouts of hazardous smog in the last few years. Average density of PM2.5 in Beijing stayed at 58 micrograms per cubic meter of air in 2017, down by 20.5 per cent compared to the average level in 2016, and a decrease of 35.6 per cent compared to 2013, a report by the Beijing Municipal Environmental Protection Bureau said. The city has met the goal set by the government in 2013, the report said. Density of three major pollutants - sulfur dioxide, nitrogen dioxide and PM10 - also dropped sharply to 8, 46 and 84 micrograms per cubic meter of air, down 20 per cent, 4.2 per cent and 8.7 per cent respectively compared to 2016. The capital saw 226 good air days in 2017, 28 days more than in 2016. The number of heavy pollution days decreased by 16 to 23, according to the report. However, while the pollution levels in the city, which for years experienced the worst air-quality with heavy industrial and auto emissions saw a bright winter, the polluted smog has returned to haunt the city for the past few days despite the onset of summer. Even today the city's air quality index showed 125 which is unhealthy for sensitive groups while the temperatures climbed to 28 degrees. The official report said city's water quality has also improved. The density of ammonia nitrogen dropped to 2.62 milligram per liter of water, down 51.5 per cent compared to the previous year, the report said. A total of 92 per cent of the city's wastewater was treated last year, according to the report. The city used more than one billion cubic meters of recycled water last year, 26.6 per cent of the city's total water consumption.