Trace contamination of the International Space Station (ISS) by formaldehyde?a known carcinogen? is a significant potential threat to crew health. The spacecraft maximum allowable concentration (SMAC) in air is only 40 parts per billion and ambient concentrations appear to be increasing as formaldehyde outgasses from a variety of plastic components. Monitoring formaldehyde levels is difficult because few analytical methods can achieve sufficient sensitivity from instrumentation that can be adapted for space-based operation. The current detection method ? using absorbent ?badges? ? relies on post-flight analysis of the adsorbent material. Some of those measurements show formaldehyde concentrations close to the SMAC upper bound. As a result, a need exists for a reliable, fully automated analyzer that can provide continuous monitoring of formaldehyde concentrations on board the ISS. The target detection sensitivity is 10 ppb and the response time should be ≤10 minutes. Southwest Sciences proposes the development of an optical analyzer for formaldehyde that is expected to meet the requirements of space-based operation. The instrument will be compact, light weight, require little electrical power and no consumables, and will be able to operate for extended periods (months to years) without maintenance or re-calibration.