What is the reason for this high outdoor VOC level with strange pattern of slow rise and sudden falling?
I have an atmotube pro air quality sensor placed outside in a cup with a large bowl placed over the top of it to protect it from the wind and any rain but to allow air to filter through easily.
I'm trying to understand what might be the reason for the pattern of VOCs I am seeing.
The weather is partly cloudy today with some intermittant sunshine in my south of England city (the sun is not that strong with it being January). The monitor is placed on top of a 1st floor bay window. 542
The wind is about 10mph NW and the temperature 6-7C. I live in a 250k populated densly packed city on a quiet road 150m from a couple of 30kmh limit busy roads and junction.
I have had similar patterns of high VOC levels in the past with them suddenly falling. I think it starts to rise when it gets sunny then falls as soon as the sun goes away.
What would be the most common reason for this pattern (sometimes the readings go to 2.0ppm)
VOCs emitted from roof when sun hits it (it is a lead roof)? Traffic building up? Pollution blown in from somewhere else? Fault with sensor? Traffic pollution turning into something else in the sunshine? Sudden changes in wind when it becomes cloudy?
13:02 - 13:55 in one minute intervals, it is this difference in one minute that I am confused about 0.763, 0.37
0.356, 0.363, 0.373, 0.439, 0.507, 0.572, 0.622, 0.661, 0.763, 0.37, 0.356, 0.346, 0.334, 0.341, 0.354, 0.38, 0.347, 0.354, 0.333, 0.319, 0.323, 0.335, 0.35, 0.373, 0.477, 0.55, 0.35, 0.338, 0.341, 0.344, 0.345, 0.362, 0.333, 0.348, 0.364, 0.403, 0.519, 0.583, 0.624, 0.69, 0.66, 0.702 542