I saw this article the other day on the internet. It mentions Nanning.It talks about carbon monoxide problems in Chinese homes today. http://wcrcleaders.com/china-carbon-monoxide-deaths-html-2/ Just last week we had a problem ( in the USA) with an old carbon monoxide monitor in an apartment downstairs. Alarm went off at 1:00 in the morning on Saturday. Gas company was called. False alarm. A new monitor with a 3 digit display costs about 35 dollars from Amazon.