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L Project dust report | April 20 - 27, 2020

Updated May 1, 2020

The safety of our customers, employees and the general public is the MTA's top priority. We take seriously public concerns about air quality in the L tunnel and in the stations along the L during this period of construction and have adopted very conservative standards for exposure of the public to dust and silica, a part of the dust generated by the demolition of concrete. Additionally, we strictly adhere to all federal and state occupational safety regulations for our employees. 

Dust concentration standard and recorded levels: 20 April — 27 April 2020

Below are measurements of dust concentrations taken in the public space at the Bedford Av and 1 Av stations during the period from 12pm on Monday 20 April 2020 until 12 PM on Monday 27 April 2020. Dust levels before, during and after the work during this period were well below the conservative health-protective standard of 3000 µg/m3 of dust. This standard was established by the American Council of Government Industrial Hygienists to be health protective for people exposed to these levels for 8 hours a day over a 45-year working career. As there is no established standard exposure limit to dust for the short periods of time that a typical subway passenger will pass through the station, we are using this long-term chronic standard so as to measure against a very conservative health-protective benchmark. 

Silica concentration standard

There was no potential silica-producing work in the tunnel this week. As such silica samples were not collected during this reporting period.

All potential silica-producing L Project work was completed as of March 23, 2020. Should any additional related work arise in the future, silica sampling will resume. In the meantime, monitoring non-silica dust level is continuing to assure compliance with the project limits that were established to protect public health.

This is the chart for the weekly dust report for L Project tunnel rehabilitation. The rehabilitation is complete as of April 27. No exceedances are reported as in previous weeks.