2015_07_16 Initial testing (MBTA Red line: Alewife to Ashmont)

I started at Harvard station at 3:50. I went to alewife to start from the very end of the Red line. I assume that I got there around 4. I took two measurements at each station. One when there was no subway and another when the subway was coming in. I stood at the middle of the platform, couple steps behind the yellow line. The purpose of the second measurement was to see what happens to air quality when subway comes in and people get on and off. The arrival of subway creates breeze so it will increase an amount of dust presumably. People will also emit some gasses so there will be a difference also. It was quite difficult to get the right timing for the second measurement. It was okay when the station had many commuters but when there were not that many people, I had to get on the subway before it finished taking the measurement. From Harvard square station to The South station there were a lot of people. Other stations had fewer people meaning that the second measurements taken in those ones were not as accurate as the measurements taken in crowded stations. From JFK to Ashmont, there were almost no people at the station. People looked at the setup, but just two people approached me and asked me questions.

I will compare all the gas levels when there was no train, and when the train is coming in. Hydrogen level doesn’t change much. Overall, Hydrogen level tends to drop when the train is arriving although some stations show the opposite. Ozone level also stays mostly the same regardless of the presence of cars, and it also drops when the train arrives. It was the same for Alcohol as well. Dust sensor indicated a significant difference. I expected that as subway went through the rail, it would create the wind and would storm up the dust. Out of 17 stations, dust sensor worked at 14 stations. 3 stations just showed 0.62 for some reason. Out of 17 stations, only 6 stations had higher dust concentration on the second measurement. That indicates that it is actually dustier when the car is not around.

Hydrogen level was high in Alewife, Davis, Park street and Ashmont (over 380). It was low at Charles, South, JFK, and Shawmut. Except for South, three other stations, Charles, JFK, and Shawmut stations were located outside.

There was not much difference in ozone level between stations. Fields corner had the lowest ozone level (86.9, 93.8) and the highest was Alewife (138.1, 137.5).

Alcohol level had slight variations. It was the high in Park street, Downtown crossing, South, and Broadway (over 170). All of those stations, except for Broadway had a lot of commuters. When there are more people, there are probably more people who drank alcohol. Alcohol level was low in outside stations (around 130) and stations where there were almost no people.

Carbon Monoxide didn’t have many variations. It was highest in Porter square (182) and lowest in Charles (146).

Dust sensor showed the biggest variation. It was highest in Ashmont when a train was arriving (2475) and lowest in Kendall also when the train was coming in (78).

Sensors seem to work fine except I need to look into hazardous gas.