Indoor measurements

The major drawback to using the Florida study to support the correlation between indoor and soil measurements was that the indoor measurements were obtained from 3-day closed-house charcoal measurements, and soil radon was obtained from 1-month alpha track measurements buried 1 ft beneath the soil surface. Comparisons of charcoal and alpha track data are generally not recommended since they are quite different measurement techniques, and represent radon levels over different time periods. However, the study was subjected to numerous quality control checks including deployment of alpha track detectors in 10% of the houses to obtain a check on indoor air measurements made by charcoal canisters. In spite of the measurement drawbacks, the study indicates that soil radon measurements taken alone are not a dependable predictor of potential indoor radon concentration. 

The simultaneous measurements were performed in 5 rounds with more than 8 measurements for the four instruments except the DSC (one measurement) made in each round. The indoor measurement with the ERM was continuously made in the laboratory together with the PFC for several months afer making simultaneous measurements using the five devices. These results were compared with each other. 

For the latter case, comparing the average of a set of indoor measurements to a known outdoor level, the sample size may be as small as five. From Table V, we see that 5 measurements are sufficient to detect a ten fold difference between an indoor average and a known outdoor level with a. 91 probability when the coefficient of variation is 2.5. (Note that if ol and og are both equal to 1, the coefficient of variation is approximately 2.5.)... 

In addition to these techniques, there are passive samplers for N02 that have been used for unique situations such as indoor measurements. For example, in the Palmes Tube, N02 diffuses through to a surface coated with triethanolamine and is trapped in the form of NOJ. The nitrite is subsequently measured colori-metrically (e.g., see Boleij et al., 1986 Miller, 1988 and Krochmal and Gorski, 1991). As with most, if not all, such wet chemical methods, interferences can arise, for example, from PAN (Hisham and Grosjean, 1990) and HONO (Spicer et al., 1993b). 

DEHP was detected in samples (one from a commercial site and five from residential sites) of both dust and air obtained from all sites (Rudel et al 2001). In dust, the concentration of DEHP ranged from 69.4 to 524 g/g dust, with a mean concentration of 315 g/g dust. In air, 4/6 sites had DEHP at concentrations above the minimum detection limit (MDL), ranging from 0.02 to 0.114 g/m3, with a mean concentration of 0.061 g/m3. In another study, indoor measurements ofDEHP taken in six homes in the spring of 2000 ranged from 0.04 to 0.23 g/m3 (Otake et al. 2001). In one workplace (plastic melting facility), a value of 11.5 g/m3 was measured in air (Rudel et al. 2001). 

After sealing and packaging, these devices are delivered to the different laboratories where they are subjected to outdoor I/V measurements and further indoor measurements, at a variety of cell temperatures. Generally, a qualitatively similar temperature behavior is observed in indoor and outdoor I/V measurements of all devices studied. Figures 5.47 and 5.48 summarize the temperature dependence of the principal cell parameters (V/c, Jsc, r/, and FF) derived from indoor and outdoor I/V measurements of typical devices. Outdoor and simulator measurements of Voc show a linear decrease with increasing temperature (Figs. 5.47b and 5.48). 

Fig. 5.48. Temperature dependence of normalized photovoltaic parameters for a typical polymer fullerene solar cell derived from indoor measurements of its I/V curves. The ordinate axis displays all parameters normalized to their measured values at 25°C, namely, Jsc 3.1 mA/cm2, Voc- 840 mV, FF 0.55, and 77 1.45%. Active cell area 7.5 mm2. Measurements were performed with a class A solar simulator (Spectrolab X-10). Measured data were corrected to their corresponding AM 1.5 values using a mismatch factor of 0.9...

A more recent study by Fromme et al. [8] used the data from indoor measurements in Canada and Norway and estimated that, for the general population... 

Interferometric systems, usually heflum-neon lasers, offer precise distance measurement over a scale of distances <100 m and in an indoor environment. Such devices are suitable for dimensional control of machine tools (see Machining MATERIALS, ELECTROCHEMICAL). 

A method which competes with interferometric distance measurement is laser Doppler displacement. In this approach the Doppler shift of the beam reflected from a target is measured and integrated to obtain displacement. This method also is best suited to use indoors at distances no more than a few hundred meters. Table 2 compares some of the characteristics of these laser-based methods of distance measurement. 

The test must be carried out indoors, reasonably free from draughts. Themiocouples should be used to measure the temperature, and the ambient temperature can be measured by thermocouples or thermometers. 

Figure 15.16 Typical indoor-type wound primary CTs for measuring or protection (Courtesy Kappa Electricals)...

Aim to protect the health and safety of everyone m the workplace and ensure that adequate welfare facilities are provided. Covers e.g. general ventilation, temperature m indoor workplaces, lighting, cleanliness, space requirements, condition of floors and traffic routes, measures against falls/fallmg objects, washing facilities. 

Measurement of specific chemical or biological contaminants can be very expensive. Before expending time and money to obtain measurements of indoor air pollutants, you must decide how the results will be used (e.g., comparison to standards or guidelines, comparison to levels in complaint-free areas) what substances(s) should be measured where to take, samples when to take samples what sampling and analysis method to use so that the results provide useful information. 

What instruments would you use to measure air flow direction and intensity in an indoor air quality audit. 

Modern measuring techniques, an increased requirement for the indoor environment, and the efficiency of filters in separating particles led to EUROVENT 4/9 1992 Method of Testing Air Filters Used In General Ventilation for the Determination of Fractional Efficiency. This method also provides the basis for the next revision or upgrade of European Standard EN 779 1999. 

Measures undertaken to improve the indoor air quality (lAQ) have the same effect by upgrading the filter class, increasing the air change rate, etc. These small improvements have grown both in number and in size, little by little. 

Demand-controlled ventilation (DCV) is one approach to reduce energy consumption due to ventilation, that is gaining popularity in both industrial and nonindustrial applications. It is used in cases where ventilation requirements vary with time, regularly or irregularly. The control is based on a specified level of indoor air quality by means of continuous measurement of the parameters, that are expected to primarily determine the lAQ, such as the concentration of the main contaminant liberated from the production process. The principle is thus similar to the one in some better-known nonindustrial applications, e.g., CO2 levels in rooms with dense human occupancy (theaters, classrooms, etc.) or nicotine concentration in smoking rooms. See also Section 9.6. 

In the case of gaseous contaminants, the tracer gas is selected to simu late as well as possible the properties (density, temperature) and momentum of the real contaminant. It is essential to ensure that the tracers arc nontoxic, chemically nonreactive, nonadsorptive on indoor surfaces, and inexpensive. The mixing of the tracer with the actual gaseous contaminant before its release or the release of the tracer with a density near that of the air will improve the validity of the simulation. With tracers, the most difficult task in practice is the relationship of the discharge between the tracer and the real contaminant. Case-by-case techniques to release the tracer are necessary in practice. With tracer gases, the procedure for capture efficiency is described in detail in the European Standard. - The tracer gas concentrations are measured in the exhaust duct for two release locations as illustrated in Fig. 10.108. 

In industrial ventilation the majority of air velocity measurements are related to different means of controlling indoor conditions, like prediction of thermal comfort contaminant dispersion analysis adjustment of supply airflow patterns, and testing of local exhausts, air curtains, and other devices. In all these applications the nature of the flow is highly turbulent and the velocity has a wide range, from O.l m in the occupied zone to 5-15 m s" in supply jets and up to 30-40 m s in air curtain devices. Furthermore, the flow velocity and direction as well as air temperature often have significant variations in time, which make measurement difficult. 

The precision of a thermal anemometer is dependent on the instrument quality and the conditions of use. A general rule is, the lower the measured ve locity, the higher the inaccuracy and vice versa. When measuring very low indoor velocities, around 0.1 m s, the relative error can be as high as 100% and not much lower than 30%. Low velocities are extremely difficult to measure with accuracy. 

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