In January 2018, Minneapolis became the first major city to go entirely perc-free at all dry-cleaning operations. Tetrachloroethylene, more commonly known as perc, is an industrial solvent commonly used as a dry-cleaning agent but also used in metal degreasing. Exposure to perc is harmful for workers, customers, and surrounding neighborhoods. Through funding partnerships between the dry cleaner owners, the City of Minneapolis Green Business Cost Share Program, the Minnesota Pollution Control Agency, Environmental Initiative, and Lowry Hill East, East Isles, Tangletown, and Windom neighborhood groups, all dry cleaners in Minneapolis are now perc free.
Exposure to perc can cause varying health effects. Breathing high levels of perc for a short period of time can cause dizziness, drowsiness, headache, and incoordination. Over-time exposure may cause changes in mood, memory, attention, reaction time, and vision. The U.S. Environmental Protection Agency considers perc a likely human carcinogen. Studies in humans suggest that exposure to perc may lead to a higher risk of bladder cancer, multiple myeloma, or non-Hodgkin’s lymphoma. The Minnesota Department of Health developed a chronic, inhalation, health benchmark for perc of 2 μg/m3 and an acute health benchmark of 20,000 μg/m3. The health benchmark is the level that is likely to pose little or no risk to human health. Above that level, there may be a concern.
The Air Quality in Minneapolis: A Neighborhood Approach study was conducted over a two-year period, from November 2013 through August 2015. During that time, air samples were collected four times a year from over 100 locations around the City and analyzed for volatile organic compounds (VOCs), including perc. Perc was detected at locations across the entire City. Of the more than 900 samples collected over the course of two years, perc was detected a total of 132 times. Of those detects, 100 were above the health benchmark of 2 μg/m3. Of the 100 sample detects above the health benchmark, 29 of those were collected outside a dry-cleaning facility that used perc. The average level of perc outside the dry-cleaning facility was 176.8 μg/m3. Levels detected at samples outside of this dry-cleaning facility were higher than expected and concerning. These results clearly indicated that action to make the switch to a safer dry-cleaning process was necessary.
"Becoming the first perc free dry-cleaning city is an example of how Minneapolis partners with businesses to lead positive environmental change"
The effort to make all dry cleaners in Minneapolis perc-free began when results from the Air Quality in Minneapolis: A Neighborhood Approach study showed higher than expected levels of perc outside of a dry cleaning in Minneapolis. It was previous thought that perc wasn’t released from dry cleaners in high levels. This was concerning as dry cleaners are often located in residential neighborhoods with many residential homes in close proximity. Average levels of perc inside the dry cleaners before the transition were not only above the chronic health benchmark, but above the acute health benchmark. This level of exposure became a concern for public health officials in the Minneapolis Health Department.
Levels outside of the facilities were also detected at levels over the chronic health benchmark which is concerning, particularly in situations where a residential home is near a dry cleaner. As part of the Green Business Cost Share Program contract, air samples from inside and outside the facilities were collect both pre- and post-transition to a perc-free cleaning system. Average and maximum levels of perc measured before the conversion are shown in the table below.
Each of the dry cleaners transitioned to EcoSolv® Drycleaning Fluid which is 100% hydrocarbon-based cleaner made up of isoparaffins. Isoparaffins have a low toxicity. After each dry cleaner transitioned to EcoSolv® and had the last of their remaining drums of perc removed from the site, the second air sampling was conducted. These samples were collected within approximately two to four weeks after the transition. Perc is slow to break down in air, and levels will likely continue to decrease over time. Average and maximum levels of perc measured after the conversion are shown in the table below.
Becoming the first perc free dry-cleaning city is an example of how Minneapolis partners with businesses to lead positive environmental change. These direct investments in solutions are made through our Green Business Cost Share Program. To learn more about our programs, visit:
Jaša Žižek Fuis, Product Manager, Wastewater Treatment & Andreja Peternelj, Wastewater Treatment Development Manager, Treatment Plant & Tomaž Ružič, Product Manager, DISNet WS - Water systems, Petrol d.d., Ljubljana, Petrol Group