Exposure Assessment Program

Burden, Need and Impact

NIOSH strives to maximize its impact in occupational safety and health. The Exposure Assessment Program (EXAP) identifies priorities to guide investments, and base those priorities on the evidence of burden, need and impact.

HazMat firefighter using sensing meter for examining gas levels


Exposure assessment is critical to both understanding the scope of occupational safety and health problems, and confirming whether interventions are effective. Burden cannot be measured without appropriate and adequate exposure assessment methods to obtain baseline data and assess changes. Exposure assessment methods are necessary to identify the exposure/hazard and determine whether injury or illness can be associated with an exposure/hazard. In order to design and implement effective worker protections, researchers must know whether a hazard is present, if there is the potential for exposure, trends in exposure, nature of the potential health risks from exposures to the hazard, and if certain subpopulations of workers are more at risk than others.


No matter the type of research project or approach to protecting worker health, exposure assessment measurement methods are essential. EXAP is uniquely suited to contribute in three ways, due to its central position in the occupational safety and health community:

  • Developing guidance for how to conduct exposure assessments in a variety of occupational assessments. It is important to know which exposure assessment method to use, and how to implement it properly.
  • Developing new or improved exposure assessment methods to ensure measurements are accurate and able to detect even lower levels of agents in workplaces.
  • Develop new or improved sensors for assessing exposures to make it faster and easier to identify and measure exposures, some even in real time.



NIOSH has published its methods in the NIOSH Manual of Analytical Methods (NMAM) for the last 40 years.  With thousands of NIOSH methods downloaded, they are extremely relevant and widely used throughout the world for not only occupational research bur environmental research as well. Currently, there are over 300 methods in the NMAM that have undergone a rigorous review process to establish their scientific integrity.

Many NIOSH sensors have a role in occupational health and safety practice. EXAP estimates that over 35,000 NIOSH-developed sensors have been sold over the past ten years. For example, two NIOSH methods were commercialized and are currently sold under the MethAlert and MethChek brand names. These wipes are used by first responders, industrial hygienists, site remediation technicians and state and local health departments to detect methamphetamine residues.

Page last reviewed: November 12, 2019