Page 33 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

6 1 Air Emissions

As such, the potential chronic health effects of particulate matter are lung cancer,
pulmonary emphysema, bronchitis, asthma, and other respiratory infections [10]. In
addition, inhaled gaseous air pollutants may slow the action of the tiny cilia and
result in the deep embedment of more particles in lung tissue.
Although human beings have mechanisms to remove and clear particles from the
respiratory system, air pollutants can quickly overcome these natural defense
mechanisms. Once the chemicals carried by the air pollutants are absorbed into the
bloodstream, they can be transported to a distant organ or tissue to create a variety
of adverse effects. The respiratory effects result in skin and eye irritation, inflam-
mation, allergic reaction, cough, chest pain, bronchitis, pulmonary emphysema,
lung cancer, decreased respiratory efficiency, diminished pulmonary circulation,
and enlargement and weakening of the heart and blood vessels.
In the United States of America (USA), where air is relative clean on average,
lung dysfunction, which is a result of exposure to air pollutants, ranks among top 10
most important occupational diseases and injuries. Consequently, these effects can
result in the increase in medical costs and premature death. Individual reactions to
air pollutants depend on the type of pollutant a person is exposed to, the degree of
exposure, the individual’s health status and genetics. People staying in offices are
exposed to indoor air pollutants rather than those who work outdoors. Elevated
exposure to air pollutants correlates to increases in emergency room visits, hospital
admissions, and premature deaths.
Children and elders are more vulnerable to air pollution. Children are very
sensitive to the effects of air pollution, as they breathe more rapidly and inhale more
pollutants per body weight than adults do. Therefore, their lungs have a greater
chance of exposure to harmful air pollutants. Fine particles can harm lung devel-
opment and cause early childhood asthma. Polluted air may contribute to permanent
lung damage during the development periods of children’s lungs. Recent studies
also indicate that air pollutants have a larger impact on people who are already ill
than unhealthy ones.
The short-term health effects of air pollutants are quantified using an air quality
index (AQI) [14]. Computation of the AQI requires multiple air pollutant con-
centrations, often in terms of the presence of five common pollutants—sulfur
dioxide, nitrogen dioxide, carbon monoxide, suspended particulates, and ground-
level ozone [26]. The calculated AQI values are divided into ranges, and each range
is assigned a descriptor and a color code. A lower AQI value indicates better air
quality.
In the USA AQI, for example, there are six levels of AQI, Good (0–50),
Moderate (51–100), Unhealthy for Sensitive Groups (101–150), Unhealthy
(151–200), Very unhealthy (201–300), and Hazardous (>300).
• Good indicates that the air quality is considered satisfactory and poses little or
no risk.
• Moderate air quality is acceptable except for a very small number of individ-
uals, such as those who are sensitive to ozone. These people may experience
respiratory symptoms.