mitigation

Health Canada’s cross-Canada residential radon survey report from 2012 demonstrated that roughly 7% of Canadian homes contain radon levels above the Canadian guideline of 200 Bq/m3. The research outlined in this paper evaluates the effect of ventilation rates on radon levels in two homes located in Ontario, Canada. The first case study consisted of short-term (2 day) radon monitoring in a home using three ventilation strategies; one heat recovery ventilator (HRV) running, two HRVs running, and both HRVs turned off.

Τhe present article deals with the development and testing of photovoltaic pavement for heat island mitigation. The scope of this study is to evaluate its contribution to the balance of the Urban Heat Island phenomenon. For this reason, we made a photovoltaic pavement for purely experimental reasons (dimensions 3.5x1.3m) that consists of two different voltage polycrystalline photovoltaic panels. On top of them, a triplex security glass with a nonslip silk screen, PVB standard 1.14 mm was placed.

A soil gas measurement method developed earlier [1] was applied to boreholes drilled to belowfoundation depth. Radon concentration and permeability were measured at 50 cm intervals. Inradon prone areas permeability showed to increase with depth over several orders of magnitude,indicating a low permeability top layer with a thickness of 0.5 m and more. A radon availabilityindex (RAI) was empirically defined and the maximum RAI of each boring proved to be a reliableindicator for radon problems in nearby houses.

Results of an investigation into factors contributing to elevated indoor radon concentrations insupposedly mitigated homes suggest that, in areas of extensive karst geological development,fluctuations in indoor radon concentrations may be extraordinary in magnitude, duration and seasonaloccurrence.

The indoor radon program in the US. started in the early 1970's in response to CongressionalHearings that recommended the initiation of radon measurements in certain parts of the united Stateswhere enhanced radon caused by contaminated uranium and radium tailings was suspect. In the mid1970's, the Department of Energy (DOE), Environmental Measurements Laboratory (EML),conducted the first indoor radon survey in the New York City Metropolitan area. The two year studyrecommended that radon surveys should be expanded throughout the US.

Radon as an indoor air pollutant has been extensively researched worldwide over the past thirtyyears. However, radon is only one of several other important pollutants present in the indooratmosphere. In addition to radon as an ubiquitous indoor pollutant, the simultaneous presence ofother non-radiological pollutants, such as toxic alkanes found in the working environment, needs tobe accounted for its integrated mitigation approach.

A new mechanical ventilation system which continuously controlled the indoor-outdoor pressure difference was installed in six houses, where the long-term radon levels ranged from 670 to 3 080 Bq/m³. When the new system had operated for several months, the indoor radon levels decreased to levels from 120 to 600 Bq/m³ , the effective dose reductions being from 40 % to 88 %.

During the past 10 years the U.S. Environmental Protection Agency (EPA) has pursued a national strategy to address radon remediation in buildings to meet its goals of radon risk reduction. Initially the approach developed and demonstrated remediation methods and techniques in existing residences with specific attention to the effect of regional climate variations and the differences in housing construction. A number of studies and demonstrations were undertaken to accurately characterize and evaluate the effectiveness of several remediation methods and techniques.

A computational sensitivity analysis was conducted to identify the conditions under which residential active soil depressurization (ASD) systems for indoor radon reduction might most likely exacerbate or create back-drafting of natural-draft combustion appliances. Parameters varied included: house size; normalized leakage area; exhaust rate of exhaust appliances other than the ASD system; and the amount of house air exhausted by the ASD system.