BACKGROUND Air pollution is a major problem in urban\industrial areas, like Tehran, and has several impacts on human health. This study aimed at assessing concentrations of criteria air pollutants (CO, SO(2), NO(2), O(3), PM(10)) in Tehran, extracting patterns of hourly, daily, weekly, and monthly variations of concentrations, and making comparisons to National Standards and WHO Guidelines. M...

A newly designed gas-sampling device using end-tidal CO(2) to separate dead space gas from alveolar gas was evaluated in 12 mechanically ventilated patients. For that purpose, CO(2)-controlled sampling was compared with mixed expiratory sampling. Alveolar sampling valves were easily controlled via CO(2) concentration. Concentrations of four volatile substances were determined in the expired and...

A passive air sampler, using 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole, was evaluated for the determination of formaldehyde in indoor environments. Chromatography paper cleaned using a 3% hydrogen peroxide solution was experimentally determined as being the optimum absorption filter for the collection of formaldehyde (0.05 microg cm(-2) formaldehyde). From a linear-regression analysis betwe...

The evaluation of air quality is an important topic. It is well known that lichens have a set of characteristics that make them well suited for biomonitoring purposes. Sampling lichen diversity is not as expensive as chemical analysis and for this reason a dense sampling grid is possible thus reducing the costs of analysis. Lichen diversity can be used to identify more disturbed areas, resultin...

Although studies of the composition of alveolar air have been invaluable to the advance of respiratory physiology a precise definition of alveolar gas pressures and the accurate sampling of alveolar air have proved elusive goals (1). Owing to the cyclic nature of the ventilatory process the partial pressures of 02 and CO2 in the alveoli are changing continually (time factor) (9), and, owing to ...