Tuesday, November 1, 2016

Speck Performs Well in Independent Testing

Speck Performs Well in Independent Testing
Researchers at the Center for Air Resources Engineering and Science at Clarkson University recently evaluated the Speck sensor along with three other low-cost PM sensors at their laboratory in Potsdam, NY.  In the testing, the four low-cost PM sensors were exposed to Arizona Test Dust (ATD) and particles from cigarette smoke (CS), and their responses compared to the responses of more complex laboratory PM measurement instrumentation.  These two particle sources represent extremes in particle sizes with ATD being dominated by large particles and CS being dominated by fine particles.  Although all four low-cost PM sensors showed variations in their ability to correctly characterize the number concentrations of the two test particles, the results of PM mass measurements were much more convincing. For PM mass measurements, results of the tests showed that the Speck sensor was the only one to consistently yield PM mass concentrations in agreement with the laboratory instrument data for both sources of PM with consistent coefficients of regression, R2, of 0.92 for cigarette smoke and 0.96 for Arizona Test Dust. The other low-cost PM monitors showed varied responses to the two types of test particles and, generally, lower or inconsistent R2 values.  These results demonstrate the Speck’s ability to reliably indicate PM mass concentrations for a wide spectrum of particle sizes and potential sources.  The full test results can be found in the following publication - http://dx.doi.org/10.1016/j.jaerosci.2016.08.010.  

Dave Litton

Focus on Ozone

Focus on Ozone

Ozone comes in basically two forms – the good and the bad. Good ozone is the ozone formed in the stratosphere that forms a protective layer to block out harmful ultraviolet radiation from reaching the Earth’s surface. We have all heard of the ozone hole created primarily by excess chlorofluorocarbons, or CFC’s, that deplete the stratospheric ozone and let the harmful ultraviolet rays reach the Earth’s surface. But ozone has another face, the bad ozone, that is present in our atmosphere in the air we breathe.

This ozone is formed from the reaction of oxides of nitrogen with volatile organic compounds, or VOC’s, in the presence of sunlight. The optimum conditions for the formation of ground-level, bad ozone occur when the air temperatures are in the 80’s and 90’s and the winds are calm.

Ozone is one gas that is known to make respiratory problems, such as asthma or chronic obstructive pulmonary disease (COPD), worse and exposure to ozone tends to affect young children and senior citizens the most. The Environmental Protection Agency (EPA) monitors ozone levels and it is one gas used to calculate the Air Quality Index, or AQI. When atmospheric ozone is at a concentration of 54 ppb (parts per billion) or lower, the AQI is 50 or less and the air quality is said to be good. But as the ozone concentration increases to values greater than 70 ppb, its effects begin to be felt by some persons who may have existing health problems such as asthma or COPD. At much higher levels, ozone action days may be proclaimed which means that the outdoor ozone concentrations are high enough to affect many more people and people are generally told to stay indoors to avoid health problems. A short synopsis of ozone can be found on the website below that is maintained by the EPA.


Considerable more detail about the health problems associated with ozone can be found on the following website dedicated to ozone awareness.


We all know that if ozone is present in the atmosphere outside our homes and offices, then some of this ozone may make its way indoors adding to indoor air pollution. But in an attempt to clean the indoor air of gaseous pollutants, many people turn to ozone generators that are said to remove contaminants and pollutants from the indoor air. The bottom line is that these ozone air cleaners create ozone and that the ozone created may make your indoor air more hazardous to breathe. The problem is potentially severe, so much so that the EPA has dedicated a website about the hazards of ozone air cleaners. It can be found at the link below and is well worth the read since it also contains some basics about reducing indoor air pollution for a healthier lifestyle.

https://www.epa.gov/indoor-air- quality-iaq/ozone- generators-are- sold-air- cleaners

Senior Scientist, Airviz Inc.