The Indoor Chemical Human Emissions and Reactivity (ICHEAR) project: Overview of experimental methodology and preliminary results

Abstract

With the gradual reduction of emissions from building products, emissions from human occupants become more dominant indoors. The impact of human emissions on indoor air quality is inadequately understood. The aim of the Indoor Chemical Human Emissions and Reactivity (ICHEAR) project was to examine the impact on indoor air chemistry of whole-body, exhaled, and dermally emitted human bioeffluents under different conditions comprising human factors (t-shirts/shorts vs long-sleeve shirts/pants; age: teenagers, young adults, and seniors) and a variety of environmental factors (moderate vs high air temperature; low vs high relative humidity; presence vs absence of ozone). A series of human subject experiments were performed in a well-controlled stainless steel climate chamber. State-of-the-art measurement technologies were used to quantify the volatile organic compounds emitted by humans and their total OH reactivity; ammonia, nanoparticle, fluorescent biological aerosol particle (FBAP), and microbial emissions; and skin surface chemistry. This paper presents the design of the project, its methodologies, and preliminary results, comparing identical measurements performed with five groups, each composed of 4 volunteers (2 males and 2 females). The volunteers wore identical laundered new clothes and were asked to use the same set of fragrance-free personal care products. They occupied the ozone-free (<2 ppb) chamber for 3 hours (morning) and then left for a 10-min lunch break. Ozone (target concentration in occupied chamber ~35 ppb) was introduced 10 minutes after the volunteers returned to the chamber, and the measurements continued for another 2.5 hours. Under a given ozone condition, relatively small differences were observed in the steady-state concentrations of geranyl acetone, 6MHO, and 4OPA between the five groups. Larger variability was observed for acetone and isoprene. The absence or presence of ozone significantly influenced the steady-state concentrations of acetone, geranyl acetone, 6MHO, and 4OPA. Results of replicate experiments demonstrate the robustness of the experiments.

Quantification and source characterization of volatile organic compounds from exercising and application of chlorine‐based cleaning products in a university athletic center

“…Future experiments could explore the variables that govern the enhancement of VOCs, H 2 O, NH 3 , and CO 2 by controlling the exercise type, duration, and intensity, and measuring the heart rate, and weight of the athletes. Experiments exploring the sources of VOCs could also be conducted, for example, by interfacing a breathing apparatus with a Vocus or CIMS to explore what emissions are predominantly from breath during exercise, followed by experiments in a chamber to sample whole‐body emissions 82 . Controlling future experiments with fragrance‐free, pre‐washed clothing can also help determine whether the VOC emission is predominantly from PCPs.…”

Ozone Initiates Human-Derived Emission of Nanocluster Aerosols

“…A detailed description and experimental methodology are given in Bekö et al 26 Briefly, measurements were made in a 22.5 m 3 stainless-steel climate-controlled chamber (Fig. S1).…”

“…S1). 26,27 The chamber was ventilated with 100% outdoor air at an air change rate of 3.2 ± 0.1 h -1 . A combination of newly installed F7 fiber filters and high efficiency activated carbon molecular filters ensured an NCA-and ozone-free background in the unoccupied chamber (< 1 NCA/cm 3 and < 1 ppb, respectively).…”

Respiratory performance of humans exposed to moderate levels of carbon dioxide

“…The VOC measurements in Table 1 indicate that the levels did not reach instrument detection limit of 15 ppb. Typical indoor chemical human emissions are not expected to be over these limits 30 . The levels may yet have varied for the three sessions, due to difference in ventilation.…”