Author Archives: Wei Dai

Air pollution and large-scale construction project ( Air pollution in China part II)

I realized that when talking about air pollution, many people will automatically equal it with CO2 pollution, global warming and the contamination brought by large chemical plants. However, most of us will ignore the huge damage brought by large-scale construction projects. The pollution did by large projects is actually much larger and common than what did by chemical plants domestically, especially in developing countries. True, one chemical plants makes more pollution than one large scale construction project and the pollution done by chemical plants usually more instinct and dangerous. However, just because it’s so obvious that chemical plants can pollute the air, the Chinese government has to “take care of it”, and they did. Until 2014, more than 1/3 chemical plants, including all the large chemical plants was closed or accepted Industrial Upgrading and Transformation. The total amount of chemical plants has massively reduced, so has the pollution they make. Right now, the fact is that the main pollution in China, especially east, south and north, is Particle Matter.   (Particle matters (PM), smog-forming pollutants (like NOx,hydrocarbons ) and toxics are the air pollution that can make damage on our health in a very short time, not only the CO2. ) One large project can make a huge amount of these pollution by both its construction process and the construction equipments. Let’s talk about the equipments. there are about 19 types of construction equipments usually used in large projects and  the five highest-polluting  types are responsible for about 65 percent of PM and 60 percent of NOx  in California in 2005. And that’s way better than the condition of air in China.  The total number of the “top five” construction equipments in each large project is approximately about 24 ( way smaller than the number in reality), and for a secondary city like Linyi, there usually have at least 40 large-scale construction project working at a same time period and usually they will last for years.

24 × 40 × 365 = 350400,That’s the number of the “top five” working in a small secondary city of China in one day. If we pick up some large, strong secondary city’s data, it will be much more horrible. Take the example of Nanjing, until the last month of 2014, Nanjing has near 2000 c=large scale constructions projects. Assuming construction equipments in each large project is still approximately about 24.

We have 24 ×2000 × 365 = 1.752 × 10^7

I should mentioned there are total 19 types of construction equipments and we should know that the air pollution in China that made by secondary city is lighter than that made by big cities like Shanghai. My suggestions on dealing with this problem has been posted in the Part I ( my last post before this one).

I’ll leave this datas and resources here, you can read the forms, estimate and imagine the damage brought by large projects.

The Health Risks of Construction Pollution in California by Don Anair





南京明年内关闭 136家化工厂

Air Pollution in China Part 1

I found this article from, it reminds me of my home town, Nanjing. I think the the most direct action right now to reduce the air pollution is to slow down the development speed a little bit.  reducing the number of large-size projects in a certain time period and extend the length of the total time limit of all projects will observably decrease the pollution degree. You will be amazed when I tell you my personal experience in Nanjing before and after the Youth Olympic Games: before the opening ceremony about a month ago, we still have more than 20 large-size construction projects working normally and the AQI number is about 200 which means the air is very unhealthy. Before the opening ceremony about weeks ago, the government finally decided to close some of projects. By the day that half of the LSP( large-size project) were closed, the blue sky came out. By the day that all the LSP were closed, the AQI dropped massively into about 100, which is medium, and even lower. However, after the Olympic Games, those projects were opened again, and suddenly the air pollution became heavy again. The main problem is that most of the government officers in China have limited eye-sites,  and are too focusing on their personal contributions and something can be done fast. Every one want to make some big deal before they “leave their seats” and the only thing they can imagined that can be done quickly and can represent the sign of economy development is large-size construction projects. Thus the development of the city or country becomes the game of who can build more buildings within a limited time. If they cannot slow their speed and calm down, paying more attention on those long-term sustainable new project, the current situation of China’s air pollution will never get better. I will bring more figure next time.

Heavy air pollution blankets northern China, reaches ‘hazardous’ levels

Wei Dai

So the cooking is one of his hobbies?

I did not find out any descriptions about professor Roe’s hobby and research interests on syllabus. Since there are several photos of him climbing rocks, I assumed that climbing is one his hobbies in addition to mathematics studies. But where can I find any sign presenting that he likes cooking?

Wei Dai

Wei Dai

I am an IDS major freshman and you can call me Joshua. I do have talent on art but not on mathematics. To be honest, I forget the reason why I chose this course but surely it is for fulfilling the a requirement of mine to take one more Quantification course. About my understanding on the words “sustainability and resilience” I would say that it’s an idea of how to make a thing working efficiently and effectively and how to gain most profit with fewest cost. I’m not sure if my opinion is right but anyway, it always been a pleasure to learn something new.

This is my personal site, check it out: