“…It should be noted that due to high temperatures and stable atmospheric conditions, several days with relatively high NH 3 levels were recorded in our observation, consequently leading to a relatively large mean NH 3 concentration. The NH 3 level in Beijing was lower compared to the measurements in some other cities around the world; for example, in Kaohsiung, Taiwan (31.5 ± 16.1 µg m -3 , winter 2006, Tsai et al, 2014);Kanpur, India (26.4 ± 5.8 µg m -3 , winter 2007, Behera andSharma, 2010); and Lahore, Pakistan (50.1 ± 16.9 µg m -3 , winter 2005, Biswas et al, 2008). However, in Beijing, the NH 3 level was still higher than those observed in some other cities of China including Shanghai (6.6 µg m -3 , autumn 2012, Shi et al, 2014) Hu et al, 2008).…”