Summary: This memorandum reports preliminary information on the monitoring program at SIMS Metal Management. Technical information shows that the SIMS monitors sample air at a rate that is over 500 times lower than the rate for monitors at Perez Elementary School. This explains why some data from SIMS are being reported as “not detected” when there are probably meaningful levels of pollutants present. The monitors at SIMS seem inadequate if the community is to have useful site‐specific information about several metals of concern.
On April 21, 2022, the US Environmental Protection Agency issued a “Request to Provide Information Pursuant to the Clean Air Act” under its authority in Section 114 of the Act. This required SIMS Metal Management to install monitoring equipment to report on some pollutants that are of concern to the community. This included five monitors for continuous particulate matter (PM10) detection, three monitors to periodically sample volatile organic compounds (VOCs), and three to periodically sample PM10, including metal hazardous air pollutants (HAPs). SIMS submitted a plan for this in June 2022. The monitor program became active in late September 2022, with the first data, covering one week only, released in October.
This memo concerns one part of the results: for all of the HAPs (antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, nickel, and selenium), the data report “ND,” or “not detected” for the amount present. The same is true of most VOCs.
The “ND” results for the HAPs contrasts with data from the monitoring program at Perez Elementary School that regularly includes detectable amounts of several of these metals: cadmium, chromium, lead, manganese, and nickel (Table 1).
Table 1: Data on average concentrations of five metal HAPs measured at Perez Elementary school, in nanograms per cubic meter
It is important to note that “not detected” does not mean “not present.” It simply means the amount of the pollutant is below the reporting limit of the test method. A key part of the test method is how much air is sampled during a three‐day sampling period. How much air is sampled depends on how much air flows through the monitor. The air flow rates of the SIMS monitors are very different from those at Perez.
The monitors at SIMS, according to the plan they submitted, use a Met One Instruments E‐Sampler Dual Ambient Monitor/Sampler. This has an air flow rate of 2.0 liters of air per minute. According to the IL EPA’s State of Illinois Ambient Air Monitoring 2023 Network Plan, the Perez monitor uses a Tisch Industries’ TE‐5170‐D Total Suspended Particulate Mass Flow Controlled High Volume Air Sampler. This has an air flow rate of 1100 to 1700 liters per minute (listed in the specifications as 1.10 to 1.70 m³ per min).
A comparison of the equipment specifications shows that that the air flow rate for the SIMS monitors is more than 500 times lower than the air flow rate for the Perez monitor. This 500‐fold difference means it is difficult if not impossible to interpret the SIMS data relative to Perez. The SIMS data may consistently report “ND” while there are actually meaningful amounts of the HAPs present that the SIMS monitoring system just cannot detect.
Even with a 2.0 liter per minute flow rate, the monitors at SIMS would probably detect lead above the EPA action level of 150 nanograms per cubic meter. But in a community with documented environmental health concerns, the level of concern for lead may be far below 150 nanograms per cubic meter. The other metals have no action level established by the EPA. But the levels detected at Perez are still an important concern, especially given recent scientific reports on, for example, the correlation of elevated levels of manganese, copper, nickel, and vanadium in children with the incidence of asthma (Madrigal et al. 2021).
Given the difference in flow rate, it is reasonable to conclude that the monitors at SIMS will simply not detect the levels of pollutants that are consistently detected at Perez. The monitors at SIMS seem inadequate if the community is to have useful site‐specific information about several metals of concern.