Indoor concentrations

Fig. 23-1. Representation of home with various sources and sinks for indoor air pollutants (A), exchange (B), indoor concentration (C), outgassing of building and furniture materials (D), irvfiltration from soils (E), removal on interior surfaces.

Radon gas is formed in the process of radioactive decay of uranium. The distribution of naturally occurring radon follows the distribution of uranium in geological formations. Elevated levels have been observed in certain granite-type minerals. Residences built in these areas have the potential for elevated indoor concentrations of radon from radon gas entering through cracks and crevices and from outgassing from well water. 

Outdoor inhalation exposure is mainly due to traffic, energy production, heating, and natural factors such as pollen and mineral dusts. These outdoor sources of pollution also affect indoor air quality. The indoor concentration is typically 20-70% of the corresponding outdoor concentration. Occasionally the indoor concentrations of an external pollutant (especially radon) may even exceed the concentrations outdoors. ... 

At typical indoor concentrations, COj is not thought to be a direct cause of adverse health effects however, COj is an easily-measured surrogate for other occupant-generated pollutants. Eye, nose, and throat irritation headaches lung cancer may contribute to heart disease buildup of fluid in the middle ear increased severity and frequency of asthma episodes decreased lung function. ETS is also a source of odor and irritation complaints. 

Nighttime pre-cooling using outdoor air— Nighttime ventilation may result in decreased indoor concentrations of mdoor-generated pollutants when occupants arrive at work. Once again, proper precautions must be taken to... 

Martilla O, Haahtela T, Silakoski I, et al. 1994a. The South Karelia air pollution study Relationship of outdoor and indoor concentrations of malodorous sulfur compounds released by pulp mills. J Air Waste Manag Assoc 44 1093-1096. 

From the measured indoor Rn-222 concentration during the heating season, measurements of equilibrium factors and assessments of the seasonal variations, it is possible to assess population averaged indoor concentrations of Rn-222 progeny in Norwegian dwellings. 

A. There is no correlation between Mr and Mn this means, for example, that the average indoor concentration of radon in various counties is not correlated with the amount of cigarette smoking in those counties... 

The range of radon decay-product concentrations found in houses in southwest England spans three orders of magnitude. A few dwellings have been found where levels exceed 0.6 WL. It is clear that there are likely to be an appreciable number of houses in this region with indoor concentrations higher than 120 mWL. In 1982, the Department of the Environment identified two local authorities in the county of Cornwall that were willing to lend council property to test... 

Initial studies of the indoor concentrations of radon and its decay products were carried out with all exterior doors and windows closed, but with all internal doors fully opened. The radon production rate for the whole house was determined by measuring the 218Po concentration in indoor air and in the air outside the dwelling and by determining the ventilation rate. The radon production rate, K, is given by (Cliff, 1978b) ... 

Conclusion TVOC concentration for combined indoor/outdoor air was 169.9 pg nr3 and 420.8 pg m3 at residential and roadside site respectively. At residential site, the indoor and outdoor mean concentration of TVOC was of 236.3 pg nr3 and 103.5 pg nr3 respectively. The average indoor concentration at roadside site was 453.3 pg nr3 whereas at outdoor it was 388.4 pg nr3. At both the sites, the indoor TVOC levels were higher than that at outdoors. Mean I/O ratio at residential site was 2.3 with a range of 1.7 to 2.7 while at roadside site I/O ranges from 0.9 to 1.3 with a mean value of 1.1. At residential site, contribution of VOCs at indoor and outdoor was found to be 70% and 30%, clearly indicating dominant indoor sources, whereas at roadside it was 54% and 46% for indoor and outdoor respectively giving evidence of vehicular emission effect. Seasonal trend for TVOC at outdoors was in the order of winter > summer > monsoon whereas for indoors it was winter > monsoon > summer at both the sites. 

FIGURE 15.3 Indoor concentrations of N02 measured in ice skating rinks using different types of power for the ice resurfacers. The median and the 25th and 75th percentiles are shown in each case (adapted from Brauer et al1997). 

There are some differences in indoor levels of particulate matter in areas with low outdoor compared to high outdoor levels. In the case of high outdoor levels, the indoor concentrations tend to be somewhat lower than those outdoors for example, Colome et al. (1992)... 

In short, the indoor concentrations of particles depend on the outdoor levels, the ventilation system and exchange rates, and the presence of indoor sources such as cigarette smoke. 

Offermann, F. J., S. A. Loiselle, A. T. Hodgson, L. A. Gundel, and J. M. Daisey, A Pilot Study to Measure Indoor Concentrations and Emission Rates of Polycyclic Aromatic Hydrocarbons, Indoor Air, 4, 497-512 (1991). 

Weschler, C. J., H. C. Shields, and B. M. Shah, Understanding and Reducing the Indoor Concentration of Submicron Particles at a Commercial Building in Southern California, J. Air Waste Manage. Assoc., 46, 291-299 (1996). 

Fischer PH, Hoek G, van Reeuwijk H, Briggs DJ, Lebret E, van Wijnen JH, Kingham S, Elliott PE (2000) Traffic-related differences in outdoor and indoor concentrations of particles and volatile organic compounds in Amsterdam. Atmos Environ 34 3713-3722... 

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