​​RE: California Code of Regulations Title 8, §5199.1. Aerosol Transmissible Diseases – Zoonotic regulation, Subsection (d)(4) Respiratory Protection

​

California Department of Public Health (CDPH) acknowledges that dairy farms with infections of avian influenza A (H5N1) “bird flu" in cattle or otherwise under quarantine order, movement restriction, or other infection control order are subject to subsection 5199.1(d)(4) of the Aerosol Transmissible Diseases – Zoonotic regulation. 

One of the requirements of subsection (d)(4) is that “employees who work in enclosed areas shall use, at a minimum, elastomeric facepiece respirators or powered air purifying respirators (PAPR) with appropriate cartridges, unless the employer has demonstrated through objective evidence, that such use is not necessary to protect employees." Additionally, “the employer shall provide and ensure that employees use appropriate eye protection, unless employees use full facepiece respirators or PAPRs that provide eye protection."

Currently, CDPH recognizes that N95 respirators provide sufficient respiratory protection against aerosols in enclosed areas where infected cattle may be present. Use of N95 respirators must be coupled with appropriate eye protection, which includes goggles and/or face shield.

Guidance for dairy farm workers on the type and level of eye and respiratory protection is based on evolving knowledge of the currently circulating avian influenza A (H5N1) viruses (clade 2.3.4.4b, genotype B3.13) in 2024 and the routes of exposure that could lead to infection in the dairy farm setting. Intensity and duration of exposure, personal protective equipment (PPE) efficacy, and consideration as to whether wearing a certain type of respirator will adversely affect a worker's ability to perform their tasks or will create a risk to the safety of the worker should all be included in PPE recommendations and requirements.

Avian influenza A viruses, like H5N1, can cause infections of eyes and respiratory tract.[1] Recent case reports have described eye infections (conjunctivitis) following close exposure to sick cows infected with virus on dairy farms, especially following milking of infected cows.[2]​ [3]​ Human infections in the United States associated with this H5N1 virus have primarily presented as conjunctivitis with or without mild respiratory symptoms.[4]​ This is consistent with case findings associated with the 29 infections reported as of 11/22/2024 of workers in California. To date, every dairy farm worker in California with a confirmed eye infection has had eye irritation or redness. Respiratory symptoms have also been reported in some, but these have been less common. All but one confirmed case to date had virus detected in the eye, but a minority had virus detected in the respiratory tract.  Human respiratory infections from exposure to the avian influenza viruses in splashes, sprays, or aerosols may be less likely to occur than eye infections due to the very low prevalence of avian influenza receptors in the upper respiratory tract compared to on the surface of the eye.[5]​

In relation to subsection 5199.1(d)(4) Respiratory Protection, CDPH has recommended prioritizing the use of goggles or a face shield and a filtering facepiece respirator, such as an N95 mask, for tasks where exposure could occur as aerosols or dusts containing infectious H5N1 virus, which can then enter the eyes, nose, and mouth. PPE is especially important with high-exposure tasks, such as when milking cows or working in milking parlors, or when having close exposure to an infected animal. When working in an enclosed space with potentially infected cows, CDPH recommends that workers wear a filtering  facepiece N95 respirator for respiratory protection. Where the respirator might get splashed with milk, CDPH also recommends a face shield to protect the respirator. Per the Aerosol Transmissible Diseases – Zoonotic regulation, dairy farms should provide and ensure wear of these items in addition to “protective clothing and equipment, such as coveralls or similar whole-body clothing, head coverings, gloves, and foot coverings" in “restricted areas in which occupational exposure to potentially infectious animals."

Additional Considerations regarding different respirators:

Elastomeric respirators and powered air purifying respirators (PAPRs) are alternatives to disposable N95 respirators in enclosed spaces. There is substantial evidence that elastomeric half-mask respirators provide a higher level of protection than N95s.[6]​ Elastomeric half-mask respirators provide a better seal to a person's face than a N95 due to the larger surface area of the respirator in contact with facial skin, the greater elasticity of the material, and the greater resistance to deformation. Some people find elastomeric respirators to be more comfortable than N95s. Full facepiece elastomeric respirators are expected to provide five-fold higher level of protection than half mask respirators and protect both the respiratory system and the eyes. Elastomeric respirators and PAPRs have an advantage over filtering facepiece respirators in wet environments because they don't get soggy and lose their shape which could affect how well they protect the wearer.

Elastomeric respirators and PAPRs must be cleaned at least daily, and possibly more frequently if they get splashed with infectious material. If farms do not clean and maintain respirators correctly, infectious material could be inadvertently introduced onto workers' faces. In addition, battery packs for PAPRs must be charged periodically.

N95 respirators are not reusable, must be replaced frequently (at least once or twice per shift), and must be disposed of and replaced once they become wet, soiled, deformed, or when the straps are overstretched. N95s do not provide sufficient protection once wet. In wet environments, CDPH recommends that workers wear face shields over their filtering facepiece respirator to protect an N95 respirator from becoming wet.

N95 respirators have been supplied free of charge, through state and local stockpiles, to dairy farmers and other groups in response to outbreaks since last summer 2024. With the ready availability of these filtering facepiece N95 respirators, the assumption that they provide sufficient protection according to their assigned protection factor, and current evidence for inefficient spread of this H5N1 virus through respiratory droplets, CDPH maintains N95s are an acceptable alternative to the current requirement for employers to provide, and employees to wear, elastomeric respirators or PAPRs, in enclosed areas on dairies that may have cows with bird flu.

As we learn more about this virus, CDPH will continue to update our recommendations to reflect the latest science and information on transmission. ​​

References:

[1] Belser JA, Lash RR, Garg S, Tumpey TM, Maines TR. The eyes have it: influenza virus infection beyond the respiratory tract. Lancet Infect Dis. 2018 Jul;18(7):e220-e227. doi: 10.1016/S1473-3099(18)30102-6. Epub 2018 Feb 21. PMID: 29477464; PMCID: PMC6035055.  

[2] Uyeki TM, Milton S, Abdul Hamid C, Reinoso Webb C, Presley SM, Shetty V, Rollo SN, Martinez DL, Rai S, Gonzales ER, Kniss KL, Jang Y, Frederick JC, De La Cruz JA, Liddell J, Di H, Kirby MK, Barnes JR, Davis CT. Highly Pathogenic Avian Influenza A(H5N1) Virus Infection in a Dairy Farm Worker. N Engl J Med. 2024 Jun 6;390(21):2028-2029. doi: 10.1056/NEJMc2405371. Epub 2024 May 3. PMID: 38700506.

[3] Morse J, Coyle J, Mikesell L, Stoddard B, Eckel S, Weinberg M, Kuo J, Riner D, Margulieux K, Stricklen J, Dover M, Kniss KL, Jang Y, Kirby MK, Frederick JC, Lacek KA, Davis CT, Uyeki TM, Lyon-Callo S, Bagdasarian N. Influenza A(H5N1) Virus Infection in Two Dairy Farm Workers in Michigan. N Engl J Med. 2024 Sep 12;391(10):963-964. doi: 10.1056/NEJMc2407264. Epub 2024 Aug 7. PMID: 39115081.

[4] Webby R, Uyeki T. An Update on Highly Pathogenic Avian Influenza A(H5N1) Virus, Clade 2.3.4.4b, The Journal of Infectious Diseases, 2024 15 Sep 2024; 230(3):533–542, doi:10.1093/infdis/jiae379

[5] Belser JA, Rota PA, Tumpey TM. Ocular tropism of respiratory viruses. Microbiol Mol Biol Rev. 2013 Mar;77(1):144-56. doi: 10.1128/MMBR.00058-12. PMID: 23471620; PMCID: PMC3591987.

[6] Lawrence, R. B., Duling, M. G., Calvert, C. A., & Coffey, C. C. (2006). Comparison of Performance of Three Different Types of Respiratory Protection Devices. Journal of Occupational and Environmental Hygiene, 3(9), 465–474. https://doi.org/10.1080/15459620600829211

National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Health Sciences Policy; Committee on the Use of Elastomeric Respirators in Health Care; Liverman CT, Yost OC, Rogers BME, et al., editors. Reusable Elastomeric Respirators in Health Care: Considerations for Routine and Surge Use. Washington (DC): National Academies Press (US); 2018 Dec 6. 2, Elastomeric Respirators. https://www.ncbi.nlm.nih.gov/books/NBK540078/

Bray C, Vanberkel PT. A framework for comparing N95 and elastomeric facepiece respirators on cost and function for healthcare use during a pandemic- A literature review. Health Policy. 2023 Aug;134:104857. doi: 10.1016/j.healthpol.2023.104857.

Barros AJ, Sifri CD, Bell TD, Eby JC, Enfield KB. Effectiveness of Elastomeric Half-Mask Respirators vs N95 Filtering Facepiece Respirators During Simulated Resuscitation: A Nonrandomized Controlled Trial. JAMA Netw Open. 2021 Mar 1;4(3):e211564. doi: 10.1001/jamanetworkopen.2021.1564. PMID: 33724389; PMCID: PMC7967080.​