Ultrafine particles are airborne particulates of less than 100 nm in aerodynamic diameter. Examples of ultrafine particles are diesel exhaust particles, products of cooking, heating and wood burning in indoor environments, and more recently, products generated through the use of nanotechnology. Studies have shown that ambient ultrafine particles have detrimental effects on both the cardiovascular and respiratory systems, including a higher incidence of atherosclerosis and the exacerbation rate of asthma. Ultrafine particles have been found to alter in vitro and in vivo responses of the immune system to allergens and may also play a role in allergen sensitization. The inflammatory properties of ultrafine particles may be mediated by a number of different mechanisms, including the ability to produce reactive oxygen species, leading to the generation of pro-inflammatory cytokines and airway inflammation. In addition, because of their small size, ultrafine particles also have unique distribution characteristics in the respiratory tree and circulation and may be able to alter cellular function in ways that circumvent normal signaling pathways. Additionally, ultrafine particles can penetrate intracellularly and potentially cause DNA damage. The recent advances in nanotechnology, while opening up new opportunities for the advancement of technology and medicine, could also lead to unforeseen adverse health effects in exposed humans. Further research is needed to clarify the safety of nanoscale particles, as well as the elucidation of the possible beneficial use of these particulates to treat disease.

Climate change is a constant and ongoing process. It is postulated that human activities have reached a point at which we are producing global climate change. This article provides suggestions to help the allergist/environmental physician integrate recommendations about improvements in outdoor and indoor air quality and the likely response to predicted alterations in the earth’s environment into their patient’s treatment plan. Many changes that affect respiratory disease are anticipated. Examples of responses to climate change include energy reduction retrofits in homes that could potentially affect exposure to allergens and irritants, more hot sunny days that increase ozone-related difficulties, and rises in sea level or altered rainfall patterns that increase exposure to damp indoor environments. Climate changes can also affect ecosystems, manifested as the appearance of stinging and biting arthropods in new areas. Higher ambient carbon dioxide concentrations, warmer temperatures, and changes in floristic zones could potentially increase exposure to ragweed and other outdoor allergens, whereas green practices such as composting can increase allergen and irritant exposure. Finally, increased energy costs may result in urban crowding and human source pollution, leading to changes in patterns of infectious respiratory illnesses. Improved governmental controls on airborne pollutants could lead to cleaner air and reduced respiratory diseases but will meet strong opposition because of their effect on business productivity. The allergy community must therefore adapt, as physician and research scientists always have, by anticipating the needs of patients and by adopting practices and research methods to meet changing environmental conditions.

Concurrent recurrent selection experiments were conducted for five cycles to compare three methods of selection for grain yield in maize (Zea mays L.): (1) combining ability with an inbred line (Inbred Tester Method), (2) combining ability with the broad‐base parental population (Parental Tester Method), and (3) yield S2 lines per se (S2 Progeny Method). The 15 selected populations were then crossed with the parental population and with another broad‐base synthetic to evaluate changes in general combining ability, and also were tested as randommated and selfed populations per se.A significant linear increase in general combining ability over cycles was obtained for all methods, but the Inbred Tester Method was significantly more effective than the other two methods (4.4% gain per cycle, compared with 2.4 and 2.0% for the Parental Tester and S2 Progeny Methods, respectively). There was no significant difference among methods for yield of random‐mated selected populations when adjustments were made for differences in rate of inbreeding.The results indicate that the inbred tester used was homozygous recessive at many important loci. This would result in larger testcross variances and more successful selection of dominant favorable alleles than is possible with a broad‐base tester, which probably has intermediate gene frequencies at most loci. The slow progress in combining ability improvement with the S2 Progeny Method suggests that this method also was not effective in fixing dominant favorable alleles.

Carpet and rugs currently represent about half of the United States flooring market and offer many benefits as a flooring type. How carpets influence our exposure to both microorganisms and chemicals in indoor environments has important health implications but is not well understood. The goal of this manuscript is to consolidate what is known about how carpet impacts indoor chemistry and microbiology, as well as to identify the important research gaps that remain. After describing the current use of carpet indoors, questions focus on five specific areas: 1) indoor chemistry, 2) indoor microbiology, 3) resuspension and exposure, 4) current practices and future needs, and 5) sustainability. Overall, it is clear that carpet can influence our exposures to particles and volatile compounds in the indoor environment by acting as a direct source, as a reservoir of environmental contaminants, and as a surface supporting chemical and biological transformations. However, the health implications of these processes are not well known, nor how cleaning practices could be optimized to minimize potential negative impacts. Current standards and recommendations focus largely on carpets as a primary source of chemicals and on limiting moisture that would support microbial growth. Future research should consider enhancing knowledge related to the impact of carpet in the indoor environment and how we might improve the design and maintenance of this common material to reduce our exposure to harmful contaminants while retaining the benefits to consumers.

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