Outbreaks of emerging and re-remerging infectious diseases are frequently reported internationally in recent years, mainly due to global climate change, close human-livestock contact in developing countries, and globalization. Thus prevention, monitoring and control of infectious diseases are in urgent need to protect public health. High exposure risk to various infectious agents in health care facilities is of special concern, especially to airborne and droplet-borne respiratory diseases. To protect the health of public and health care workers the investigators will conduct a study to monitor indoor air quality and essential infectious aerosols in hospital(s).

A questionnaire survey will be used to evaluate the relationships between employees' health and measured indoor environmental factors. The investigators will also examine whether the current indoor air quality recommendation of their country can reasonably reduce the risk of hospital infection. In addition, simple infectious aerosol indices will be established for future environmental management and monitoring in health care facilities.

Inclusion Criteria:

• people who work in Health Care Facilities

Exclusion Criteria:

• none

people who work in Health Care Facilities