Validating low-cost indoor air quality monitors to improve exposure monitoring in nail salons

In the US, approximately 200,000 nail salon workers face chronic exposure to airborne chemicals. Health effects among this sector have been well documented and public health laws aimed at exposure reduction have been implemented across the US. In this study, we evaluated the accuracy and feasibility of using commercially available low-cost sensors as tools for workers to monitor and reduce their daily exposures. We compared the performance and utility of six commercially available low-cost total volatile organic compound (TVOC) sensors (Awair Omni, Kaiterra Sensedge, UHoo Smart Air Monitor, Airthings View Plus, Atmotube, and Atmocube) to validated reference instruments. Sensors were collocated in at least 4 different salons for 7 consecutive days during an initial baseline measurement period. Salons then received an intervention on methods to reduce exposure by utilizing existing controls and another 7 days of exposure measurements were collected. TVOC measurements from low-cost sensors exhibited moderate to strong correlations (r_s ~ 0.54 - 0.88) with readings from validated reference instruments. Accuracy of the low-cost sensors varied, especially at higher TVOC concentrations and after repeated days of use. Low-cost sensors on average underestimated TVOC concentrations at the highest quartile of exposure (Mean Absolute Error (MAE) Q4: 16.19 – 28.49 ppm) but performed more similarly to reference instruments at lower quartiles of exposure (MAE Q1: 0.69 –  2.53 ppm, Q2: 1.60 – 2.75 ppm, Q3: 5.55 – 6.85 ppm). Despite some limitations, these sensors can be valuable tools for exposure assessment, including monitoring nail salon workers' daily exposures and studying the health effects of chemical exposures in longitudinal epidemiologic studies among this group.