Low Air Infiltration Research Articles

Particle radioactivity from radon decay products and reduced pulmonary function among chronic obstructive pulmonary disease patients

BackgroundRadon (222Rn) decay products can attach to particles in the air, be inhaled, and potentially cause airway damage. Research questionIs short-term exposure to particle radioactivity (PR) attributable to radon decay products emitted from particulate matter ≤2.5 μm in diameter (PM2.5) associated with pulmonary function in chronic obstructive pulmonary disease (COPD) patients? Study design and methodsIn this cohort study, 142 elderly, predominantly male patients with COPD from Eastern Massachusetts each had up to 4 one-week long seasonal assessments of indoor (home) and ambient (central site) PR and PM2.5 over the course of a year (467 assessments). Ambient and indoor PR were measured as α-activity on archived PM2.5 filter samples. Ratios of indoor/ambient PR were calculated, with higher ratios representing PR from an indoor source of radon decay. We also considered a measure of outside air infiltration that could dilute the concentrations of indoor radon decay products, the indoor/ambient ratio of sulfur concentrations in PM2.5 filter samples. Spirometry pre- and post-bronchodilator (BD) forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) were conducted following sampling. Generalized additive mixed models were adjusted for meteorologic variables, seasonality, and individual-level determinants of pulmonary function. We additionally adjusted for indoor PM2.5 and black carbon (BC). ResultsPR exposure metrics indicating radon decay product exposure from an indoor source were associated with a reduction in FEV1 and FVC. Patients in homes with high indoor PR (≥median) and low air infiltration (<median) compared to others had a −26.9 (95% CI: −61.4, 7.7) mL and −75.4 (95% CI: −128.6, −22.2) mL reduction in post-BD FEV1 and FVC, respectively. These associations remained similar after PM2.5 and BC adjustment. InterpretationOur findings raise concern about the harmful effects of PR exposures attributable to residential radon on pulmonary function in patients with COPD.

Radon barrier: Method of testing airtightness - 2. Edition

The test method NBI 167/02 Radon membrane: Test of airtightness can be used for determining the airtightness of a radon barrier as a system solution. The test determines the air infiltration through the radon barrier for a number of levels of air pressure differences. The airflow through versus the difference in air pressure over the barrier is measured. The air pressure difference is kept constant, at a number of manually controlled levels. At each pressure level, the difference is measured in a single point close to the point where the suction for lowering the air pressure is located. Improvements to the test method were suggested. A digital stirring and control system, and a method for determining the mean air pressure difference, as well as a method for testing barriers with a very low air infiltration, were provided. The digital stirring and control system ensured automatic control and measuring of coherent values of the airflow and the difference in air pressure. The method determining the mean air pressure difference was based on measurements from 5 units placed at specific locations. The method for testing barriers with a very low air infiltration introduced the need to provide air to the side of the barrier with the low air pressure, through a well-defined opening, as a modification of the test method in general. Results, obtained using the improved test method, are shown for a number of radon barriers tested.

Air infiltration induced inter-unit dispersion and infectious risk assessment in a high-rise residential building.

Identifying possible airborne transmission routes and assessing the associated infectious risks are essential for implementing effective control measures. This study focuses on the infiltration-induced inter-unit pollutant dispersion in a high-rise residential (HRR) building. The outdoor wind pressure distribution on the building facades was obtained from the wind tunnel experiments. And the inter-household infiltration and tracer gas transmission were simulated using multi-zone model. The risk levels along building height and under different wind directions were examined, and influence of component leakage area was analysed. It is found that, the cross-infection risk can be over 20% because of the low air infiltration rate below 0.7 ACH, which is significantly higher than the risk of 9% obtained in our previous on-site measurement with air change rate over 3 ACH. As the air infiltration rate increases along building height, cross-infection risk is generally higher on the lower floors. The effect of wind direction on inter-unit dispersion level is significant, and the presence of a contaminant source in the windward side results in the highest cross-infection risks in other adjacent units on the same floor. Properly improving internal components tightness and increasing air change via external components are beneficial to the control of internal inter-unit transmission induced by infiltration. However, this approach may increase the cross-infection via the external transmission, and effective control measures should be further explored considering multiple transmission routes.

Concrete's Contribution to Sustainable Development

Abstract Concrete is the most widely used building material on earth. It has a 2,000 year track record of helping build the Roman Empire to building today's modern societies. As a result of its versatility, beauty, strength, and durability, concrete is used in most types of construction, including homes, buildings, roads, bridges, airports, subways, and water resource structures. And with today's heightened awareness and demand for sustainable construction, concrete performs well when compared to other building materials. Concrete is a sustainable building material due to its many eco-friendly features. The production of concrete is resource efficient and the ingredients require little processing. Most materials for concrete are acquired and manufactured locally which minimizes transportation energy. Concrete building systems combine insulation with high thermal mass and low air infiltration to make homes and buildings more energy efficient. Concrete has a long service life for buildings and transportatio...

Impact of Heating and Air Conditioning System Operation and Leakage on Ventilation and Intercompartment Transport: Studies in Unoccupied and Occupied Tennessee Valley Homes

Forced-air heating and air conditioning (HAC) systems caused an average and maximum increase in air infiltration rates of 1.8- and 4.3-fold, respectively, during brief whole-house studies of tracer gas decay in 39 occupied houses. An average increase in air infiltration rate of 0.33 +/- 0.37 h-1 corresponded to an incremental air leak of 240 m3/h, based on approximate house volume. More detailed tracer gas decay studies were performed in basement, kitchen and bedroom locations of six homes with low air infiltration rates (i.e., less than 0.25 h-1). The HAC mixed the indoor air efficiently between measurement sites. HAC operation also caused 1.1- to 3.6-fold increases in air infiltration rates, corresponding to absolute increases of 0.02 to 0.1 h-1. In an unoccupied research house, three-fold increases in average air infiltration rate with HAC operation (i.e., from 0.13 to 0.36 h-1) were reduced to two-fold (i.e., from 0.10 to 0.18 h-1) by sealing the external HAC unit and crawlspace ductwork system. This sealing also resulted in a 30 percent reduction in crawlspace-to-indoor transport rates with the HAC turned on. Blower door tests indicated a less than 20 percent reduction in house leakage area.

Indoor Outdoor Aerosol Measurements for Two Residential Buildings in New Jersey

Indoor /outdoor aerosols were studied in two residential homes in New Jersey by making hourly measurements of the concentration and particle size for 2 week intervals in the wintertime. Indoor particle concentrations ranged from 104 to 107 cm−3 and were highly dependent on household activities, including cooking, cigarette smoking, and use of a fireplace and a kerosene space heater. Besides producing large amounts of particles, the kerosene space heater also produced concentrations of carbon dioxide, up to 3000 ppm, and carbon monoxide, up to 9 ppm. The ratio of indoor/outdoor aerosol concentrations varied from 0.2 to 41 (correlation coefficients < 0.3), consistent with the low air infiltration rate measured (0.3–0.5 air changes/h). The results indicate that indoor particles were mainly from indoor origins. In addition, radon progeny particle-size distributions were calculated by applying the attachment theory to the measured aerosol size distribution. This mode was found to range from 0.04 to 0.1 μm, a range that is broader than the conventional results, which show the mode at around 0.1 μm.

Buildability of highly insulated and airtight structures

SYNOPSIS Four case studies are used to illustrate points of practicality and principle associated with low heat loss building envelopes. The pursuance of high standards of insulation and low air infiltration can involve the designer in research without which the risk of innovation may be unjustifiable. Nevertheless, the evidence is clear that low heat loss envelopes can be designed and built within stringent economic criteria and that the benefits from these passive forms of energy saving are considerable. On-site practical problems are present but are now regarded as surmountable, while prefabrication certainly has a role to play in high performance. The case studies challenge some common assumptions and suggest that the consequential effects of low envelope heat loss on the design and operation of the heating system cannot be ignored.

Residential noise insulation for mild climates

Since 1974 the California Building Standards Law has required that new multifamily housing, hotels, and motels be designed to prevent the intrusion of exterior noise above a community noise equivalent level of 45 dB. At about the same time, the State also adopted energy insulation standards which require low air infiltration rates for new dwellings. While these requirements seem to be complementary from the standpoint of noise insulation, the relatively mild climate of costal communities often obviates the need for air conditioning or even mechanical ventilation. This paper discusses some of the design, cost, and enforcement conflicts between adequate ventilation and noise insulation for areas with mild climates.

Science and society test VII: Energy and environment

Approximate numerical estimates are developed in order to quantify a variety of environmental effects that result from energy production. The results of these calculations are consistent with either direct observations or with more complex calculations. This paper will cover some of the possible environmental effects of the following: (1) the greenhouse effect caused by increased CO2 in the atmosphere; (2) loss of coolant accidents in nuclear reactors; (3) increased radon concentrations in buildings with very low air infiltration rates; (4) acid rain from the combustion of fossil fuels; (5) expolosions of liquified natural gas (LNG); and (6) ozone in the stratosphere.