The atmosphere may be our most precious resource. Accordingly, the balance between its use and protection is a high priority for our civilization. While many of us would consider air pollution to be an issue that the modern world has resolved to a greater extent, it still appears to have considerable influence on the global environment. In many countries with ambitious economic growth targets the acceptable levels of air pollution have been transgressed. Serious respiratory disease related problems have been identified with both indoor and outdoor pollution throughout the world....
Hydrogen economy represents the future of human civilization. Limited resources of our planet are compelling us to turn to renewable clean energy resources and hydrogen figures prominently as the energy carrier of a future sustainable energy system. There are significant challenges to be overcome in order to make hydrogen viable, in production, storage and power generation, while safety of operation is an ever-present factor that determines success or failure of a proposed solution.
A heating, ventilating, and air conditioning (HVAC) system is designed
to satisfy the environmental requirements of comfort or a process,
in a specific building or portion of a building and in a particular
geographic locale. Designers must understand a great deal beyond basic
HVAC system design and the outdoor climate. They must also understand
the process or the comfort requirements.
A study to measure indoor concentrations and emission rates of volatile organic compounds
(VOCs), including formaldehyde, was conducted in a new, unoccupied manufactured house
installed at the National Institute of Standards and Technology (NIST) campus. The house was
instrumented to continuously monitor indoor temperature and relative humidity, heating and air
conditioning system operation, and outdoor weather. It also was equipped with an automated
tracer gas injection and detection system to estimate air change rates every 2 h.
The current study was undertaken in a new manufactured house set up as a research
facility. The plan was to conduct longitudinal measurements of VOC concentrations in the
house along with measurements of key physical parameters including house air change rate,
indoor and outdoor temperature and relative humidity, and wind conditions over a period of
approximately one year. The primary objective was to evaluate changes in the emissions of
formaldehyde and other VOCs in response to time, house air change rate, and the other
Indoor air pollution poses many challenges to the health pro-
fessional. This booklet offers an overview of those challenges,
focusing on acute conditions, with patterns that point to par-
ticular agents and suggestions for appropriate remedial action.
The individual presenting with environmentally
associated symptoms is apt to have been exposed to airborne
substances originating not outdoors, but indoors. Studies from
the United States and Europe show that persons in industrial-
ized nations spend more than 90 percent of their time indoors1.
The major sources of indoor air pollution worldwide include indoor combustion of solid
fuels, tobacco smoking, outdoor air pollutants, emissions from construction materials and
furnishings, and improper maintenance of ventilation and air conditioning systems. Although
some indoor air pollutants, such as environmental tobacco smoke, are of concern globally,
profiles of indoor air pollutants and the resulting health risks are generally very different in
developed and developing countries.
The emission factors of the 14 most abundant VOCs on sequential cold weather sampling
dates (January 17 and March 12, 2003) are compared in Table 4. Indoor and outdoor
temperatures and percent RHs were approximately equivalent between these dates (Table 1).
However, the January air change rate was 0.58 h-1
versus 0.31 h-1
in March, likely due to the
difference in wind conditions. Within both the aldehyde and the terpene hydrocarbon chemical
classes, the ratio of the emission factor at the lower air change rate to the emission factor at the
higher air change rate was near...
The atmosphere is a mixture of several gases surrounding the earth's crust and has a layer
that protects and preserves the lives of human beings and keeping the materials in good
condition and functionality. Once damaged, by pollutants emitted from anthropogenic
and natural sources, the atmosphere reduces the levels of protection due to formation of
the ozone layer. The presence of contaminants in indoors and outdoors influenced by
climatic factors, has a negative effect on human health and the durability of materials.
Indoor air quality is a reflection of the outside air....
Active sampling for VOCs and aldehydes was conducted on 12 dates between August 8,
2002 and September 25, 2003. For each sampling event, the house was operated for at least 48 h
prior to sampling and during sampling at a standardized condition. In this condition, all exterior
windows and doors were closed, all interior doors were open, window vents were closed, the
HAC fan was operated continuously with the outdoor air intake sealed, and the indoor
temperature was maintained by thermostatic control of the heating or air conditioning equipment.