| 1. |
- Beko, G., et al.
(författare)
-
The Indoor Chemical Human Emissions and Reactivity (ICHEAR) project: Overview of experimental methodology and preliminary results
- 2020
-
Ingår i: Indoor Air. - : Hindawi Limited. - 1600-0668 .- 0905-6947. ; 30:6, s. 1213-1228
-
Tidskriftsartikel (refereegranskat)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. Higher repeatability was achieved for dermally emitted compounds and their reaction products than for constituents of exhaled breath.
|
|
| 2. |
|
|
| 3. |
- Langer, Sarka, 1960, et al.
(författare)
-
Squalene Depletion in Skin Following Human Exposure to Ozone under Controlled Chamber Conditions
- 2024
-
Ingår i: Environmental Science & Technology. - 0013-936X .- 1520-5851. ; 58:15, s. 6693-6703
-
Tidskriftsartikel (refereegranskat)abstract
- A major component of human skin oil is squalene, a highly unsaturated hydrocarbon that protects the skin from atmospheric oxidants. Skin oil, and thus squalene, is continuously replenished on the skin surface. Squalene is also quickly consumed through reactions with ozone and other oxidants. This study examined the extent of squalene depletion in the skin oils of the forearm of human volunteers after exposure to ozone in a climate chamber. Temperature, relative humidity (RH), skin coverage by clothing, and participants’ age were varied in a controlled manner. Concentrations of squalene were determined in skin wipe samples collected before and after ozone exposure. Exposures to ozone resulted in statistically significant decreases in post-exposure squalene concentrations compared to pre-exposure squalene concentrations in the skin wipes when squalene concentrations were normalized by concentrations of co-occurring cholesterol but not by co-occurring pyroglutamic acid (PGA). The rate of squalene loss due to ozonolysis was lower than its replenishment on the skin surface. Within the ranges examined, temperature and RH did not significantly affect the difference between normalized squalene levels in post-samples versus pre-samples. Although not statistically significant, skin coverage and age of the volunteers (three young adults, three seniors, and three teenagers) did appear to impact squalene depletion on the skin surfaces.
|
|
| 4. |
- Yang, Shen, et al.
(författare)
-
Ozone Initiates Human-Derived Emission of Nanocluster Aerosols
- 2021
-
Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:21, s. 14536-14545
-
Tidskriftsartikel (refereegranskat)abstract
- Nanocluster aerosols (NCAs, particles <3 nm) are important players in drivingclimate feedbacks and processes that impact human health. This study reports, for the first time, NCA formation when gas-phase ozone reacts with human surfaces. In an occupied climatecontrolledchamber, we detected NCA only when ozone was present.NCA emissions weredependent on clothing coverage, occupant age, air temperature, and humidity. Ozone-initiated chemistry with human skin lipids (particularly their primary surface reaction products) is thekey mechanism driving NCA emissions, as evidenced by positive correlations with squalene in human skin wipe samples and known gaseous products from ozonolysis of skin lipids. Oxidation by OH radicals, autoxidation reactions, and human-emitted NH3 may also play a role in NCA formation. Such chemical processesare anticipated to generate aerosols of the smallest size (1.18−1.55 nm), whereas larger clusters result from subsequent growth of the smaller aerosols. This study shows that whenever we encounter ozone indoors, where we spend most of our lives, NCAs will be produced in the air around us.
|
|
| 5. |
- Zannoni, Nora, et al.
(författare)
-
Effect of Ozone, Clothing, Temperature, and Humidity on the Total OH Reactivity Emitted from Humans
- 2021
-
Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:20, s. 13614-13624
-
Tidskriftsartikel (refereegranskat)abstract
- People influence indoor air chemistry through theirchemical emissions via breath and skin. Previous studies showed thatdirect measurement of total OH reactivity of human emissionsmatched that calculated from parallel measurements of volatile organiccompounds (VOCs) from breath, skin, and the whole body.In thisstudy, we determined, with direct measurements from twoindependent groups of four adult volunteers, the effect of indoortemperature and humidity, clothing coverage (amount of exposedskin), and indoor ozone concentration on the total OH reactivity ofgaseous human emissions.The results show that the measuredconcentrations of VOCs and ammonia adequately account for themeasured total OH reactivity. The total OH reactivity of humanemissions was primarily affected by ozone reactions with organic skinoilconstituents and increased with exposed skin surface, higher temperature, and higher humidity. Humans emitted a comparabletotal mixing ratio of VOCs and ammonia at elevated temperature-low humidity and elevated temperature-high humidity, withrelatively low diversity in chemical classes.In contrast, the total OH reactivity increased with higher temperature and higherhumidity, with a larger diversity in chemical classes compared to the total mixing ratio. Ozone present, carbonyl compounds were thedominant reactive compounds in all of the reported conditions.
|
|
