English

Reports environmental background radiation exposure measurements made in approximately 100 residences in the vicinity of Livermore, California showing variations in annual exposure from 52 to 130 mr. Measurements were made with CaF2:Dy (tld-200) dosimeters at quarterly intervals for a period of 1 year. Dwellings were typically wood-frame structures with stucco exteriors. Interior exposure rates were, on average, about 25% lower than those outdoors.

Reports study of the exposure rate due to the gamma-ray natural background in some representative areas of Italy using a portable high-pressure ionization chamber. In some areas spectrometric measurements were made to distinguish between contributions to the total from cosmic rays and from natural radioactive series. The measurement areas were chosen to be representative of the main geological formations.

Reports study of emanation of radon from concrete blocks enriched with uranium ore, placed in an airtight enclosure. The radioactivity of air samples was determined using a high resolution silicon diode detector system.

Contains two papers reprinted from the Jnl. of Ind. Aerodynamics:-< 1) Wind-tunnel simulation of the adiabatic atmospheric boundary layer by roughess, barrier and mixing-device methods.< Discusses the philosophy of roughness, barrier and mixing-device simulation methods. Illustrates methods by measurements of simulations in the B.R.E.boundary layer wind tunnel.

Describes tests in Exeter University library of method of determining ventilation rate by measuring the amount that the atmospheric carbon dioxide concentration in an occupied space is raised above the outside ambient level. Compares rate obtained with that expected from the fan rating. Demonstrates that in addition to the ventilation rate, the average rate of production of carbon dioxide produced by the occupants could in principle have been estimated from the data.

Uses Turk's equation to obtain CO concentration v time curves in an office and a one-family house. Compares results with similar studies, current threshold limit values and ambient air quality standards for CO. Finds model is apparently valid for CO and probably for other gaseous contaminants not affected by absorption or deposition. Concludes that commercial environments should have at least 5 cfm fresh air per occupant and that a value of 50 cfmfresh air appears to be adequate for a one-family dwelling.

Describes a method for measuring the radon concentration of three litre samples of atmospheric air without pretreatment. Apparatus used consists of a 12 in. photomultiplier with 2ns (ag) phosphor and counting chamber. A measured efficiency of 38% when the phospor is negatively changed, is in good agreement with theory. The ultimate sensitivity is governed by the background which is equivalent to a concentration of 5 x 10|-4 c/l

Describes in detail a multi-cell model for predicting ventilating airflows. Gives equations for flow through cracks, wind and stack effect. States that comparisons between prediction and measurements indicate that the method is capable of giving relatively high accuracy for a wide range of ventilation conditions. Discusses advantages and disadvantages of multi-cell and single-cell methods. Argues that multi-cell approach is potentially more accurate and more useful.

Describes investigation of the effects of five hour exposure of sixteen young people to different concentrations of formaldehyde. Physiological parameters, subjective discomfort and performance were monitored. Discusses setting of exposure standards for formaldehyde and suggests standard of 0.15 mg/m^3 for continuous exposure.< Discussion includes an account by R.Baars of developments in the Netherlands and measures taken to reduce formaldehyde concentrations in dwellings.

An air to air heat exchanger is only of value if one can control the movement of air into and out of the house. Suggests measures for reducing air leakage. describes construction of an air to air heat exchanger. Finds that heat exchanger can be used to control humidity in houses. Suggests use of a solar collector to preheat the cold outside air entering the heat exchanger.