This paper describes a comprehensive epidemiologic and toxicologic research program to evaluate whether some components and sources of PM may be more toxic than others. This question is important for regulatory agencies in setting air quality standards to protect people's health. The results show that PM from coal and oil combustion and from traffic sources was associated with adverse health outcomes, but other components and sources could not definitively be ruled out. Thus, given current knowledge, the current practice of setting air quality standards for PM mass as a whole likely remains an effective approach to protecting public health.

The prophylactic activity of intranasal human interferon-a2 (HuIFN-at2) against natural rhinovirus colds was determined in a randomized, double-blind, placebo-controlled trial. A total of 304 working adults selfadministered sprays of (107 IU/day) or a placebo once daily. During 22 days of treatment, 13 (8.5%) placebo recipients but no HuIFN-a2 recipiehts had respiratory illnesses documented secondary to rhinovirus infection (P = 0.0002). The occurrence of illness with symptoms of tracheobronchitis was lower ini HuIFN-a2 recipients (one eposide) than in placebo recipients (eight episodes, P = 0.04). In contrast, the frequency of nasal symptoms and the overall rate of respiratory illness were significantly higher in HuIFN-a2 recipients during weeks 2 and 3 of treatm'ent. Symptoms (obstruction, discomfort, blood-tinged nasal mucus) or signs (punctate bleeding sites, erosions, superficial ulcerations) of nasal irritation occurred in 40 HuIFN-ax2 recipients during week 3 (P < 0.0001 versus placebo recipients). Although the results of the current study were partially confounded by the nasal side effects of prolonged administration, they showed that intranasal HuIFN-eL2 was efficacious in preventing rhinovirus colds under natural conditions.The common cold is a major cause of morbidity and industrial absenteeism in the United States, afflicting adults an average of 2 to 4 arnd children an average of 6 to 8 times annually (2, 6). The antigenic heterogeneity of the causative viruses has prevented the development of a cold vaccine. For example, the most frequently isolated agent, the rhinovirus, has 89 identified serotypes and more that are recogniZed but presently unnumbered. Specific antiviral compounds have not yet been shown to have clinically useful prophylactic or therapeutic activity.Prevention of natural colds has not been achieved previously except by geographical isolation. However, experimental rhinovirus infections in susceptible volunteers have been prevented by intranasal administration of multiple daily doses of either leukocyte-derived human interferon (HuIFN) (3,13,14) or recombinant DNA-produced 15). A recent study has also shown that single daily intranasal doses of HuIFN-a2 gave protection against experimental rhinovirus colds in volunteers (9).The current randomized, placebo-controlled, double-blind study determined the prophylactic efficacy and tolerance of daily intranasal spraying with Virology. Nose and throat specimens were collected from subjects reporting upper respiratory illness, and the swabs were transported on wet ice in beef heart infusion broth containing 1% bovine serum albumin, vancomycin (20 ,ug/ml), gentamicin (50 ,xg/ml), amphotericin B (1 ,ug/ml) and sheep anti-HuIFN-o2 antibody (2,500 neutralizing units per ml) (8). The broth was inoculated in 0.2-ml portions onto duplicate monolayers of MRC-5 fibroblast, HEp-2, primary rhesus monkey kidney, and human embryonic kidney cells

Background: A previous observational study detected a strong positive relationship between sick leave absences and carbon dioxide (CO 2 ) concentrations in office buildings in the Boston area. The authors speculated that the observed association was due to a causal effect associated with low dilution ventilation, perhaps increased airborne transmission of respiratory infections. This study was undertaken to explore this association.

Reviews find a likely adverse effect of air pollution on perinatal outcomes, but variation of findings hinders the ability to incorporate the research into policy. The International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) was formed to better understand relationships between air pollution and adverse birth outcomes through standardized parallel analyses in datasets from different countries. A planning group with 10 members from 6 countries was formed to coordinate the project. Collaboration participants have datasets with air pollution values and birth outcomes. Eighteen research groups with data for approximately 20 locations in Asia, Australia, Europe, North America, and South America are participating, with most participating in an initial pilot study. Datasets generally cover the 1990s. Number of births is generally in the hundreds of thousands, but ranges from around 1,000 to about one million. Almost all participants have some measure of particulate matter, and most have ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Strong enthusiasm for participating and a geographically-diverse range of participants should lead to understanding uncertainties about the role of air pollution in perinatal outcomes and provide decision-makers with better tools to account for pregnancy outcomes in air pollution policies.

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