2015_07_07 Initial testing (Harvard square area - Commercial places)

Arduino board was not working properly since yesterday. It worked in my room but once I got out, the device just stopped measuring. It was a strange situation because it worked perfectly fine in the room. I was already worried to start field testing because I have already been to a station twice and had to come back because the device didn’t work. As expected, the board stopped working on the bus. I came up with a trick to reset the board every time. I just had to be extra careful of the order because ‘master count’ would be shown as 1 for every measurement. It was when I was texting Dr. Paster, that I realized the problem. I was unplugging and replugging the cord every time to start the device, which meant that something was wrong with the cord. So I bought another USB cord and plugged it in. When I saw LED blinking, I was so excited, relieved, and angry at the same time. Excited because I could take new measurements, relieved because I don’t have to keep an eye on the SD card light, and angry because it was the cord, which is not even a part of Arduino program, that was causing the problem. But anyways, I was ready to take measurements and I had to hurry because the battery was running out.

I tried to measure twice at the same location to be more consistent with the data. Most of the other sensors were consistent, but I could see that light sensor varied greatly just like the last time. Even around 8 PM, Harvard square was still quite bright (515 lux).

It was extremely humid (60+%) and hot (29+oC) around 4 PM today. At 8 PM, the temperature dropped to about 26oC but humidity rose to about 70%.

I chose Bank of America ATM space and Starbucks as my two extremes for the number of people. There was just me in the ATM space and there were more than 30 people in Starbucks. Starbucks had about 1.2 higher Hydrogen level than that of ATM space (ATM space: 172.14, Starbucks: 208.7). Ozone level was about the same (152, 151.74). Carbon Monoxide level was about 1.2 times higher in Starbucks (163.4, 190.58). The hazardous gas amount was also about 1.2 times higher in Starbucks (127.64, 154.52). By this, it can be inferred that more people means more gas.

I made a prediction that bookstore, where there are hundreds of books made of thousands of chemically produced papers would have high contamination rate. Hazardous gas and Alcohol gas level were pretty high, but I think that depended more on the number of people. Bookstore had more people than ATM space but fewer people than Starbucks, and the amount of gas seems to fall between those two extremes.

I went to three Outbound stations; Porter, Davis, and Alewife. Porter station had highest ozone level (159.98) and Alewife had the lowest (143.74). Porter station had the highest gas level, in general, including ozone, Alcohol, Carbon Monoxide, and Hazardous gas. However, the differences were small, even negligible. All three stations had much fewer commuters compared to that of Inbound stations. Alewife station had the highest ceiling (4.9m).