Improved Respirator Carbons for Ammonia Hazards

Details

• Personal Author:
  Srinivas G
• Description:
  A new ammonia (NH3) sorbent to protect agricultural workers from both chronic and acute exposure to ammonia was developed that greatly exceeded the performance of the best commercially available ammonia sorbent. In fact, by optimizing each step of the sorbent synthesis process we achieved a 144% improvement over existing commercially available cartridges, with a service life of 17.8 min/g (compared to 7.3 min/g for a 3M ammonia cartridge). The Phase I research also successfully met the criterion specified by the NIOSH standard of protecting the wearer against the penetration of 50 ppmv NH3 in the inhaled air for >/= 50 minutes when challenged with 1000 ppmv NH3. More than 700,000 agricultural workers are at risk from exposure to toxic levels of ammonia. Levels often exceed 50 ppmv with lower winter ventilation rates and reach 100-200 ppmv in poorly ventilated buildings or during periodic upsets due to inadequate manure handling. Although disposable ammonia respirator cartridges are commercially available, protecting all agricultural workers with the current technology would be cost-prohibitive. TDA's patented activated carbons that were made from inexpensive and abundant saccharides (e.g. starch and sugar) have increased mesoporosity (pores between 2 nm and 50 nm), which allowed it to be loaded with substantially more additive for ammonia adsorption, and its more open pore structure also enhanced the ammonia uptake kinetics. The ammonia sorbent has the following competitive advantages: Decreased breathing resistance, size and weight (because less carbon is required to provide the same protection) for increased wearability and comfort during long shifts; Extended service lifetime during routine use (e.g., throughout an 8-hour shift) In Phase I, extensive characterization was carried out to understand the fundamental structure (e.g., poresize analysis) and additive chemistry of both the precursor carbon and the as-manufactured and used sorbents; these analyses greatly assisted us in designing the optimal sorbent. More than 85 bench-scale ammonia breakthrough tests (scaled to the NIOSH standard conditions) were run to demonstrate the sorbent's effectiveness. Performance was benchmarked against the best commercially available ammonia sorbent (Chemsorb 1425). While we made substantial progress toward our goals during Phase I, further development and testing will be required (in Phase II) to optimize the sorbent's ammonia capacity, scale up production, incorporate it into a prototpye respirator cartridge, and qualify it for industrial use in accordance with the NIOSH standard testing procedure. We are planning eventual field tests by working with our industrial partners to scale-up production and fill prototype cartridges with our sorbent for qualification testing to register it with NIOSH prior to bringing it to market. In summary, a cost-effective, high-capacity ammonia sorbent was developed, that dramatically lowers the amount of sorbent that is needed, thereby lowering the cartridge size, weight and breathing resistance, and making a more comfortable to use mask that people might actually wear. These improvements are crucial to obtain adoption of the new ammonia respirator cartridge by the agricultural community to mitigate the long-term negative health effects of chronic ammonia exposure and help prevent fatalities due to acute inhalation injury. [Description provided by NIOSH]
• Subjects:
  Agriculture Environmental Exposure Occupational Exposure Occupational Health Personal Protective Equipment Respiratory Protective Devices Respiratory System Safety
• Keywords:
  Adsorbents Agricultural Chemicals Ammonia Chronic Exposure Equipment Design Exposure Levels Inhalation Studies Personal Protective Equipment PPE Respirators Respirator Testing

  More +
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  Colorado ; OSHA Region 8
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-34
• NIOSHTIC Number:
  nn:20052357
• NTIS Accession Number:
  PB2018-101423
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R43-OH-011009, 2018 Jan; :1-34
• Contact Point Address:
  Dr. Girish Srinivas, TDA Research, Inc., 12345 W. 52nd Avenue, Wheat Ridge, CO, 80033-1916
• Email:
  gsrinivas@tda.com
• CAS Registry Number:
  Ammonia (CAS RN 7664-41-7)
• Federal Fiscal Year:
  2018
• Performing Organization:
  TDA Research, Inc., Wheat Ridge, Colorado
• Peer Reviewed:
  False
• Start Date:
  20160915
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20170915
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:8f5fe1267165edcfa846cac1beb0e763f4f56c6e4db8b20daa2d03085ae17332800aedc1068fcf73c42f24ee90031c308599e81c4f813f0df68f9321f9c34ce0
• Download URL:
  https://stacks.cdc.gov/view/cdc/218700/cdc_218700_DS1.pdf
• File Type:
  [PDF - 1.79 MB ]