Indoor and Outdoor Ozone Level

Ozone in the upper atmosphere known as ozone layer plays an important role in protecting the organisms on the surface of earth by filtering out most biologically harmful ultraviolet (UV) light. Any significant reduction of upper atmosphere ozone can be harmful to the organisms on the surface of the earth. Overexposure to these harmful UV light can cause skin cancer in human. While the overhead ozone depletion can be harmful to organisms, the increase of ground-level ozone due to chemical reaction of pollutants is also harmful to human health. This ground-level ozone is called “an ozone layer in the wrong place” is one of the air pollutants existing in many urban centers around the world. In haling air with ozone can irritate our respiratory system and give rise to coughing, and even cause asthma.

Air pollutants are not only outdoors but also indoors, and some air pollutants are even greater indoors than outdoors. In order to determine the indoor and outdoor air quality, we used a chemical measurement to quantify ozone levels in the printer room and in outdoor environment on campus. The air was sampled by using a glass bubbler to absorb ozone, and any type of tubing to connect a pump and flow controller. In order to obtain the same volume of air samples, the sampling flow rate of the pump was set to be constant for indoor and outdoor conditions.

We found out that the ozone concentration of outdoor air was 16.8 ppb, which was slightly higher than the indoor concentration determined as 14 ppb. The results suggest that the air inside the printer room and outdoor air on campus was relatively clean in terms of the low ozone level, and the indoor air had slightly lower level of ozone than the outdoor air did. The ozone concentration reported by Downtown San Diego Today was 47 ppb which was much higher our results. The reason could be that the pre-set flow controller leads to imprecise volume of air being sampled. Since the ozone concentration was calculated based on these volumes, this could introduce errors in our results. Furthermore, the different sampling sites could also result in the consistency. If the reported ozone level was measured at downtown, the ozone concentration could be higher than our results since the higher level of vehicle exhaust in downtown could cause more ozone being formed. In addition, the inconsistency with reported value could be due to the different methods being used to determine ozone concentration as well.