Developing an Automated Nitrous Acid (HONO) Platform to Detect Emerging Pollutants in a Commercial and Domestic Environment

Nitrous acid (HONO) is an emerging household pollutant linked to adverse health effects, with levels reported higher indoors than outdoors. Under low light conditions, HONO can readily photolyze to form hydroxyl radicals, impacting our indoor air quality by generating harmful secondary pollutants. Thus, HONO formation processes must be well understood to improve indoor air quality. This work presents two new instruments: a HONO calibration source and an automated indoor HONO platform. The calibration source generates low HONO calibration mixing ratios from low ppt to tens of ppb, minimizing measurement uncertainty and identifying interferences for other HONO-detecting instruments. The source is integrated into an automated HONO platform, custom-built to perform modulated measurements of NOx and HONO in indoor air quality applications. The platform was deployed in a commercial kitchen to validate its measurements and investigate indoor chemical HONO processes in a setting that has not been previously measured at high-time resolution.