Airborne Diseases
Airborne microbes, allergens and chemicals cause respiratory disease -
inflammation in the nose, throat, sinuses, upper airway and the lung. Many
infections are acquired by inhalation of pathogens that may remain in the
respiratory system but also invade the rest of the body through lymphatic and
blood circulations.
Upper airway inflammation is often expressed congestion, coughs and sore
throats. Air pollution, both indoor and outdoor, plays a significant role in the
exacerbation of airway disease in asthmatics and may contribute to the overall
increase in asthma morbidity. Hospitalization for asthma has increased by 50%
over the past 20 years, and deaths from asthma in the United States have
increased to more than 5,000 per year. It is suggested that mortality is
particularly high in lower socioeconomic groups who are exposed to higher levels
of air pollution and have poorer access to early and effective medical care.
Ozone is an atmospheric pollutant that enhances the effect of inhaled
allergens in asthmatics, suggesting that pollutants influence lung function by
increasing airway inflammation. Over 50% of the United States population lives
in areas which exceed air quality standards for ozone, nitrogen dioxide, sulphur
dioxide, and particulates (as monitored by the U.S. Environmental Protection
Agency - EPA).
Spring or summer wheezing attacks of pollen sensitive patients is a form of
allergic asthma, usually obvious to patients and allergists alike. Indoor
allergens often play a role in maintaining year-round airway disease and may
present as rhinitis, sinusitis, asthma and/or bronchitis.
Every human alive on planet earth suffers from recurrent Upper Respiratory
Tract Infection. Over 80 % of these infections are caused by viruses, which run
their course regardless of what medications are offered. The prescription of
antibiotics to treat cold symptoms is one of the more futile actions of MDs,
responding to patient demand. The common cold is the most prevalent form of
viral infection caused by viruses such as rhino and corona viruses. More
virulent virus such as influenza and adenoviruses can begin with cold symptoms
and progress to involve the lung in patterns of inflammation that may involve
bronchi (bronchitis), bronchioles (bronchiolitis) or alveoli (alveolitis, a.k.a.
pneumonia).
Chronic inflammation is always an immune mediated process. The key questions
are what antigens initiate the inflammation? Chronic inflammation leads to
scarring and obstructive lung disease. Pulmonary fibrosis is a result of long
term inflammation in the lung. Diseases such a sarcoidosis involve
immune-mediated pulmonary
fibrosis.
The ubiquitous presence of fungi in both indoor and outdoor environments is a
potential health threat that is poorly understood and almost ignored in
medicine. Molds reproduce by releasing spores into the air. Mold spores are
usually more abundant than plant pollens. Molds grow mycelia, branching
thread-like structures that infiltrate materials. Spore bearing structures,
conidiophores, grow from mycelia.
Aerosols
Suspended particles in the air create aerosols that are important to the
behavior of whole atmosphere and play a role in determining human disease.
Natural sources of atmospheric particles are volcanoes, dust storms, spontaneous
forest fires, tornadoes and hurricanes. Clouds are a product of aerosols that
seed the formation of water droplets. Human air pollution now dominates aerosol
production over cities with negative health effects. Thick aerosols are obvious
as haze and contain a complex system of particles with adherent toxic gases such
as sulphur dioxide. NASA’s earth observatory information states:
Aerosol particles may be solid or liquid; they range in size from 0.01
microns to several tens of microns. For example, cigarette smoke particles are
in the middle of this size range and typical cloud drops are 10 or more microns
in diameter. The majority of aerosols form a thin haze in the lower atmosphere
(troposphere), where they are washed out of the air by rain within about a week.
Aerosols are also found in a part of the atmosphere just above the troposphere
(stratosphere). A severe volcanic eruption, such as Mount Pinatubo in the
Philippines in 1991, can put large amounts of aerosol into the stratosphere that
remain there for many months, producing beautiful sunsets around the globe, and
causing summer temperatures to be cooler than normal. Mount Pinatubo injected
about 20 million tons of sulfur dioxide into the atmosphere, cooling average
global temperatures over the following year by about half a degree.”
Aerosol particles from factories and power plants increase the number of
droplets in clouds that reflect more sunlight, retain water and do not produce
rain. Man made aerosols change local weather systems. The effect of greenhouse
gases such as carbon dioxide is warming the planet. The effect of aerosols is
cooling the planet. The net effect of air pollution depends on the ratio of
warming gases to cooling particles.
Over land up to a quarter of the total airborne particulates are pollens,
fungal spores, bacteria, viruses, plant and animal matter. Air inside buildings
contains local aerosols that are sometimes more concentrated and more toxic than
outdoor air. The term dust refers to the larger particles in the aerosol that
settle on walls and furniture.
A smoker in the living room of a house produces a toxic aerosol that
permeates the rest of the house. Smoke particles settle on walls and every
object in a room so that a smoker leaves a trail of contamination that
non-smokers smell as soon as they enter the room.
Indoor air contains a living aerosol of microorganisms that infect or
trigger allergic reactions. Spores of bacteria and fungi are microscopic and may
persist for months or years. You can see the indoor aerosol under the right
lighting conditions, such a sunlight streaming through a window. The abundance
of microorganisms, even in a very clean house, surprises most people who have
tests done to assess air quality.
