Comparison of Single-Point and Continuous Sampling Methods for Estimating Residential Indoor Temperature and Humidity

Abstract

Residential temperature and humidity are associated with multiple health effects. Studies commonly use single-point measures to estimate indoor temperature and humidity exposures, but there is little evidence to support this sampling strategy. This study evaluated the relationship between single-point and continuous monitoring of air temperature, apparent temperature, relative humidity, and absolute humidity over four exposure intervals (5-min, 30-min, 24-hrs, and 12-days) in 9 northern Utah homes, from March – June 2012. Three homes were sampled twice, for a total of 12 observation periods. Continuous data-logged sampling was conducted in homes for 2-3 wks, and simultaneous single-point measures (n = 114) were collected using handheld thermo-hygrometers. Time-centered single-point measures were moderately correlated with short-term (30-min) data logger mean air temperature (r = 0.76, β = 0.74), apparent temperature (r = 0.79, β = 0.79), relative humidity (r = 0.70, β = 0.63), and absolute humidity (r = 0.80, β = 0.80). Data logger 12-day means were also moderately correlated with single-point air temperature (r = 0.64, β = 0.43) and apparent temperature (r = 0.64, β = 0.44), but were weakly correlated with single-point relative humidity (r = 0.53, β = 0.35) and absolute humidity (r = 0.52, β = 0.39). Of the single-point RH measures, 59 (51.8%) deviated more than ±5%, 21 (18.4%) deviated more than ±10%, and 6 (5.3%) deviated more than ±15% from data logger 12-day means. Where continuous indoor monitoring is not feasible, single-point sampling strategies should include multiple measures collected at prescribed time points based on local conditions.

Evaporative Cooler Use Influences Temporal Indoor Relative Humidity but Not Dust Mite Allergen Levels in Homes in a Semi-Arid Climate

“…Single-point sampling can provide a rough estimate of mean indoor RH, but does not capture humidity trends in the home that may contribute to moisture excursions. In addition, RH trends measured by continuous monitoring in this and a previous study in Utah [ 21 ] show that indoor RH levels peak during evening hours. Thus, RH measurements reported by Ellingson et al may have over-estimated the daily mean by a few percentage points.…”

“…Ellingson et al (1995) estimated mean indoor RH using a participant-collect strategy, where daily single-point measures were collected during evening hours [ 18 ]. Single-point measures, however, do not capture temporal RH variation within the home, and are poorly correlated with mean indoor RH over multiple days [ 21 ]. Additionally, mean indoor RH may not be the most appropriate measure for evaluating in situ critical equilibrium conditions for mites in dry climates.…”

Measurement report: The effect of aerosol chemical composition on light scattering due to the hygroscopic swelling effect

“…Since the RH and temperature probes at the outlet of the wet nephelometer (RH outlet and T outlet ) were less affected by the humidifier, RH outlet and T outlet were used to calculate T dew-point at this position using Eq. (1) (Wanielista et al, 1997;James et al, 2015):…”

“…It has been characterized during international field experiments (Fierz-Schmidhauser et al, 2010a, b;Zieger et al, 2010Zieger et al, , 2014 and in particular China (Yan et al, 2009;Zhang et al, 2015;Kuang et al, 2016;L. Liu et al, 2018;Wu et al, 2020).…”

“…Zieger et al (2015) also found that the mass fraction of sulfates was strongly correlated with scattering enhancement, while the mass fraction of nitrates had a low correlation in Hyytiälä, Finland. Jin et al (2020) reported that apart from inorganic matter, e.g., SO 2− 4 and NO − 3 , organic species also significantly contributed to the aerosol liquid water content. They proposed that in the initial phase of a pollution event, the aerosol liquid water content contributed by organic matter accelerated aqueous-phase reactions, converting gaseous precursors into secondary aerosols which then absorb more liquid water.…”