inclusion criteria: * health care worker (hcw) in the emergency department who is anticipated to work at least 10 shifts over the duration of the study period (minimum 6 hours per shift) and anticipated to remain in the emergency department for the duration of the study (i.e., not transferring to another unit). for the purposes of the study, "health care workers" are physicians (including residents), nurses, nurse practitioners, physician assistants, respiratory therapists, x-ray technicians, social workers and support staff (including but not limited to house-keeping, and porters). * age ≥18 years. * ability to communicate with study staff in english

inclusion criteria: * health care worker (hcw) in the emergency department who is anticipated to work at least 10 shifts over the duration of the study period (minimum 6 hours per shift) and anticipated to remain in the emergency department for the duration of the study (i.e., not transferring to another unit). for the purposes of the study, "health care workers" are physicians (including residents), nurses, nurse practitioners, physician assistants, respiratory therapists, x-ray technicians, social workers and support staff (including but not limited to house-keeping, and porters). * age ≥18 years. * ability to communicate with study staff in english

inclusion criteria: - health care worker (hcw) in the emergency department who is anticipated to work at least 10 shifts over the duration of the study period (minimum 6 hours per shift) and anticipated to remain in the emergency department for the duration of the study (i.e., not transferring to another unit). for the purposes of the study, "health care workers" are physicians (including residents), nurses, nurse practitioners, physician assistants, respiratory therapists, x-ray technicians, social workers and support staff (including but not limited to house-keeping, and porters). - age ≥18 years. - ability to communicate with study staff in english

inclusion criteria: - health care worker (hcw) in the emergency department who is anticipated to work at least 10 shifts over the duration of the study period (minimum 6 hours per shift) and anticipated to remain in the emergency department for the duration of the study (i.e., not transferring to another unit). for the purposes of the study, "health care workers" are physicians (including residents), nurses, nurse practitioners, physician assistants, respiratory therapists, x-ray technicians, social workers and support staff (including but not limited to house-keeping, and porters). - age ≥18 years. - ability to communicate with study staff in english