This review presents a brief overview of the health effects and exposures of two criteria pollutants--ozone and particulate matter--and two toxic air pollutants--benzene and formaldehyde. These pollutants were selected from the six criteria pollutants and from the 189 toxic air pollutants on the basis of their prevalence in the United States, their physicochemical behavior, and the magnitude of...

The stratosphere-troposphere (ST) mode operation of the Indian mesospherestratosphere-troposphere (MST) radar provided evidence of multiple stable layer slxucmres near the tropopause and also of its "weakening" during late night hours on several occasions. Mass exchange can take place between the troposphere and the stratosphere during periods of such weakening. To examine whether there is any ...

Allergic airway diseases are related to exposure to atmospheric pollutants, which have been suggested to be one factor in the increasing prevalence of asthma. Little is known about the effect of ozone and diesel exhaust particulates (DEP) on the development or aggravation of asthma. We have used a mouse asthma model to determine the effect of ozone and DEP on airway hyperresponsiveness and infl...

Management of asthma requires attention to environmental exposures both indoors and outdoors. Americans spend most of their time indoors, where they have a greater ability to modify their environment. The indoor environment contains both pollutants (eg, particulate matter, nitrogen dioxide, secondhand smoke, and ozone) and allergens from furred pets, dust mites, cockroaches, rodents, and molds....

The influence of three effluent organic matter (EfOM) model compounds (alginic acid, peptone and natural organic matter-NOM) and alkalinity on the ozonation of cyclophosphamide (CPD) was investigated. The rate of ozone decay increased with increasing model compounds concentration in the order of peptone > NOM > alginic acid. Increasing alkalinity inhibited ozone decay at all concentrations of a...

The long-term trend of background O3 in surface air over the United States from 1980 to 1998 is examined using monthly probability distributions of daily maximum 8hour average O3 concentrations at a large ensemble of rural sites. Ozone concentrations have decreased at the high end of the probability distribution (reflecting emission controls) but have increased at the low end. The cross-over ta...

Ozone concentrations have been decreasing globally for the last 20 years in part due to increasing chlorine concentrations in the stratosphere (WMO 1999). The most dramatic example of these reductions has been identified in the high latitude southern hemisphere, where ozone levels are nearly entirely depleted in the lower stratosphere during September and October each year. This phenomenon, whi...

[1] We use a global chemical transport model (GEOS-Chem) driven by a general circulation model (NASA Goddard Institute for Space Studies GCM) to investigate the effects of 2000–2050 global change in climate and emissions (the Intergovernmental Panel on Climate Change A1B scenario) on the global tropospheric ozone budget and on the policy-relevant background (PRB) ozone in the United States. The...