Evanston’s first air quality study has generated a massive amount of material at its halfway point of three months.
Consultants from RHP Risk Management, the firm the City brought in to conduct the $272,000 study, released some raw figures at a community meeting at Fleetwood Jourdain Community Center on Aug. 29.
In the first three months, the five monitoring stations the firm has installed around a waste transfer station at 1711 Church St. have collected 12 million data points, officials said. The small sensor technology, available only recently, can record the gases on a minute-to-minute basis, said Jacob Persky, a principal with RHP and its co-founder.
“We’re at about the halfway point. We expect to have about 25 million [data points],” Dr. Persky told an audience of about 20 people. “So I hope that gives you an appreciation of why we’re waiting until the end to do the analysis on time. It’s a tremendous amount of statistical analysis to tease the numbers to understand what’s truly an interest.”
Dr. Persky presented some of the raw data at the meeting just to underscore how the numbers taken out of context could lead to wrong conclusions. Presenting figures for just one of the pollutants studied – “just standing back at a distance you are eyeballing it and saying, ‘Huh, it looks like things are good – all these data points are well below the red line,” he said, “but that isn’t an appropriate comparison.”
The data may have been collected over a time frame different from Evanston’s, he noted. It may not have taken into account weather conditions, which are also being recorded.
In addition, the data, in raw form, do not take into account special contributing factors. On July 4, for instance, particulates in the air can show sharp increases because of all the fireworks going off.
At the meeting, Kumar Jensen, the City’s Chief Sustainability and Resilience Officer and Project Manager for the study, said the study was intended as a first analysis, “and one of the products of the outcome of this study will be recommendations by RHP what additional work can be done. If there should be additional studies, if there needs to be other types of equipment, that can be part of staff’s request.”
The current study is focused only on whether the transfer station may be a source of pollutants. It does not cover an assessment of the meaning and significance of local air quality measurements from public health or health risk perspectives, RHP and City officials stressed in their presentations.
That would have to be the subject of a second study and would assess the sensors’ findings against the USEPA's monitors used in EPA monitors across the country.
According to the study’s timeline, data collection is to end Nov.13. A community meeting is to be held some time after Nov. 30 to discuss results.
A final report is to be issued in December of this year.
In the meantime, up-to-date information about the study, is available at cityofevanston.org/transfer station. The data analysis completed by RHP on collected air quality can be viewed at evanstonair.info.