To address public concern over metals in dust from its active copper mine, Montana Resources two years ago began a study of metals in larger particulates at the former Greeley School air monitoring site near the mine.
The results are in, and they look good.
For an unbiased third-party perspective on the data, MR consulted Dr. Kumar Ganesan, department head of environmental engineering at Montana Technological University.
Looking over the data from March 2019 to June 2020, Ganesan issued a straightforward assessment.
“In summary, I did not find anything alarming,” he said. “The data I have looked at so far does not show any concern for human health.”
The Montana Department of Public Health and Human Services meanwhile analyzed data from the station for just the spring and summer of 2019. In a letter to Butte-Silver Bow Health Officer Karen Sullivan, state toxicologist Matthew Ferguson drew the same conclusion for metals as Ganesan.
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“After full review and analysis of the data, all average metal concentrations in the ambient air were well below health-based screening levels,” Ferguson wrote.
Data
A 2017 study by Katie Hailer, department head of chemistry at Montana Tech, reported elevated metals in dust in the Greeley neighborhood, and those living in the neighborhood were naturally concerned. Residents have gone to the lengths of sampling accumulated dust at their homes personally.
Mark Thompson, vice president of environmental affairs at Montana Resources, said he took that concern very seriously.
“We're very proud of our safety performance here — our 11 years and counting without a lost-time incident. But our focus on protecting people isn't just our own people working on site, it's the community we live in. And so if there was a problem out there, we'd rather know about it, and then take appropriate action to address the problem. And the only way to really effectively address a problem is to first start with hard data,” Thompson said.
Butte’s air has long been monitored for particulates. For a long time, particulate matter of relatively large size — 10 micrometers, or PM10 — was the standard of concern for human health. It was changed to PM2.5, because health experts determined finer particles could penetrate the respiratory system more easily.
Hailer’s study looked at metals within PM10 and at an even larger size, everything under 30 to 40 microns, or Total Suspended Particulate.
MR decided to do its own study looking at metals in those same particulate sizes, hiring Billings based firm Bison Engineering to do the analysis.
Today, air monitoring at the Greeley station addresses all three sizes.
Hourly observation of the total amount of particulate is recorded for PM2.5, PM10 and TSP.
For PM2.5, metals including arsenic, cadmium, chromium, manganese, molybdenum, nickel and lead are sampled for a 24-hour period every six days.
For PM10, metals including arsenic, cadmium, copper, manganese, molybdenum, lead and zinc are sampled for a 24-hour period every six days, and the same metals are sampled continuously, and collected every five to seven days for TSP.
Hourly total particulate measures of PM2.5, PM10 and metal composition of PM2.5 are regulatory requirements of the DEQ.
All other sampling is done voluntarily by Montana Resources. Though Ganesan said the results spell no concern for health, Thompson said MR plans to continue monitoring.
MR set threshold guidelines for health concern in its study using a combination of Environmental Protection Agency, Agency for Toxic Substances and Disease Registry, Michigan Reference Concentration, and occupational standards. They were primarily based on chronic exposure concerns.
The monthly means for individual metals never closely approached the thresholds determined by the study.
Manganese was the closest in proximity to the threshold, but never exceeded it. The peak monthly mean for manganese was 20 nanograms per cubic meter in April 2019 for PM10, and 24 for TSP. In April 2019, a single manganese sample of 42 nanograms per cubic meter was recorded for PM10 but didn’t represent a monthly mean.
Though the DPHHS analysis used a threshold of 300 nanograms per cubic meter, Thompson said MR went with a more conservative number, 50, based on an EPA and ATSDR reference concentration.
“None of the manganese results from the past two years of monitoring and sampling exceed this value,” he said.
The Bison report notes, “Several of the metals showed higher than typical concentrations during the first month or two of sampling in 2019. That trend has not repeated itself.”
Lead, for example, which had an average monthly mean of 3 or 4 nanograms per cubic meter over the course of the study, registered a value of 82 in May of 2019. The threshold used for lead is 150.
Metals weren’t even detectable in many of the samples—more than 90% of the arsenic values and more than 85% of the cadmium values were below detection limits.
Arsenic had an average monthly mean of 1.7 nanograms per cubic meter for PM10 and 2.4 for TSP, with the threshold set at 15.
Average monthly means for the other metals were also far shy of the thresholds.
Bison is in the process of updating the report to include an additional six months of data which will bring the metals study to nearly two years. Thompson said the incoming data is consistent with the previous 18 months.
One outlier indicated in the DPHHS analysis was that on two days, March 5, 2019, and May 31, 2019, total particulate concentrations met or exceeded the World Health Organization Air Quality Guidelines. This is only an indication of air quality on those days, and doesn’t look at individual metals.
“Exposure to PM levels above the AQG has the potential to trigger acute health conditions in highly sensitive populations (e.g. individuals with asthma, children, and the elderly). There were no days when short-term PM levels were of concern for exposures to the general population,” Ferguson wrote.
“Highly sensitive people and parents of highly sensitive children should consult with the air quality forecast, including the real time reporting available online… and consider reducing prolonged or heavy exertion on days where air quality is poor,” Ferguson wrote as a recommendation.
The real-time reporting is available at: http://svc.mt.gov/deq/todaysair/
Meteorological data is also collected, and the Bison report indicated wind speed is very low at the site, and that the most common wind directions are east through south-southeast.
The Butte-Silver Bow Health Department does all of the actual field sampling at the site, both what’s required by the DEQ and for MR’s additional study.
Sullivan said the studies from MR and the state were cause for relief.
“From a public health standpoint, receiving all of these data indicate to me that we're OK. If it was otherwise, we'd be very concerned and alert the public to take precautions,” she said.
“The general public, particularly those living in the Greeley neighborhood, can take comfort from these data,” she added.
Sullivan said she plans to present the air monitoring reports to the county’s Health Study Advisory Committee, formed in February 2020, at an April meeting. The meeting is yet to be scheduled, and Sullivan said the reports will be posted to the county’s website following the meeting, most likely in late April.
The health department has been delayed in presenting the information to the public, and in holding meetings with the advisory board due to the COVID-19 pandemic, Sullivan said.
Ganesan expects to have his written assessment of nearly two years worth of data completed shortly as well.
Monitoring in action
The Greeley air monitoring station hums with machines, processing continuous data.
Twice a week, someone from the health department comes to download the data, change out the filters from the rooftop monitoring apparatuses, fire up the next monitoring cycle, box the used filters in ice and send them to labs to be analyzed.
On Tuesday, Jenna Fisher, registered sanitarian for the health department, did that duty.
Fisher started by taking the data down from computers in the station—temperature, pressure, flow and volume of air. She then climbed a ladder to the roof to change the filters for the DEQ. These measure PM2.5, of most concern to human health. She then moved on to those for MR’s studies.
“Our air’s been pretty good,” she said, holding out a slightly grayed filter. “You can kind of see some of the color on it, but not very much.”
She cranked the new filter in place.
“This one’s ready to roll,” she said.
Back downstairs in the station, Fisher changed out the old filter tape on the continuous monitoring machines that send real time data to the DEQ for PM2.5 and PM10.
The tape is patterned with circles, the darker the circles, the poorer the air quality.
There’s a notable change during wildfires and around the Fourth of July, Fisher said.
“They get pretty dark,” she said. “You kind of think of the impacts it's probably having on the public's health.”
As a sanitarian, Fisher deals with retail food inspections at bars, casinos, hotels, and campgrounds, and monitors septic systems. During the pandemic, she’s also had to do a lot of contact tracing and monitoring for COVID safety violations.
It’s been hard, she said, adding that the air monitoring station is the one of the only things that has stayed the same. She enjoys her escapes to that humming box of strange futuristic contraptions.
“It was really nice to kind of have this break,” she said. “This is like a space station. I always feel like I'm out of this world in here.”
Being smack in the middle of the latest air monitoring studies reassures her about the air quality in Butte, Fisher said.
“I live here. I raise a family here. And I think it's something we should all be concerned about. Seeing the results of this study is very, very good. It brings some peace of mind,” she said.
She said the studies show MR’s made the community a priority.
“I think that shows they do care. It’s the same thing with them. They live here. They have family here. We're a community. We all want the same outcome,” she said.
Attainment
Air quality in Butte has come a long way, said John Rolich, environmental health division manager for Butte-Silver Bow.
In 1987, Butte went on the EPA’s nonattainment list for PM10, and almost reached nonattainment for PM2.5 in 2011, Rolich said.
Falling into nonattainment for PM2.5 would have put heavy restrictions on industry, and Butte was right on the edge.
Since then, chemical mass balance studies have shown that air quality improved after the county’s wood stove change out program started in 2015.
Butte’s also since achieved attainment levels for PM10, and is likely just a few days from having that confirmed by the feds.
According to Liz Ulrich, analysis and planning supervisor for the DEQ, the redesignation of Butte’s PM10 nonattainment status is awaiting the EPA’s signature.
Based on air monitoring from 2014-2018, Ulrich said the EPA plans to approve the redesignation any day now.
“The fact that Butte qualified to be de-listed is a big deal,” Thompson said.
