A wide array of chronic illnesses and acute health impacts is associated with air
pollution exposure. Research has shown that long-term exposure to air pollutants
can reduce lung growth and development, and increase the risk of developing many
diseases including asthma, reduced lung function, susceptibility to infection, emphysema,
chronic obstructive pulmonary disease (COPD), lung cancer, and cardiovascular
disease. Air pollution increases the risk of preterm birth, impaired
brain development and developmental disabilities, and acute pneumonia in children
under 5. In 2013, the World Health Organization concluded that outdoor air pollution
is a carcinogen.
According to the National Institute of Environmental Health Sciences (NIEHS), air
pollution is a mixture of natural and human-made substances in the air we breathe.6
Ozone and particulates are major components of air pollution. Particulates are the
microscopic particles released into the air from motor vehicle exhaust, burning, and
dust. Particulates are classified according to these sizes, coarse particulates, PM10
(10 to 2.5 microns), fine particulates, PM2.5 (equal or smaller than 2.5 microns),
and ultrafine particulates (equal or smaller than 0.1 microns).
In general, the smaller particulates, fine and ultrafine, are a greater health risk since they can penetrate
deeply into the lungs, and the ultrafines can even reach the bloodstream. A warming
climate is increasing levels of the ozone that is formed when sunlight interacts with
fossil fuel emissions. Heat, sunlight, and lack of wind are conditions that favor the
combination of particulates and ozone into thick smog— a frequent air quality hazard
in densely populated cities such as Beijing and Delhi.
Outdoor air pollution involves exposures that take place outside of the built environment.
Examples include fine particles produced by the burning of fossil fuels
and fires of all kinds (e.g., from wildfires and the coal and petroleum used in energy
production and that caused by traffic); noxious gases (sulfur dioxide, nitrogen oxides,
carbon monoxide, chemical vapors); ground-level ozone (a reactive form of
oxygen and a primary component of urban smog); and tobacco smoke. Outdoor air
pollution is difficult to avoid, but we can take action when alerted to the level of
The U.S. Environmental Protection Agency (EPA) establishes an air quality index
(AQI) for five major air pollutants regulated by the Clean Air Act. Each of these
pollutants has a national air quality standard set by EPA to protect public health:
• Ground-level ozone
• Particle pollution (also known as particulate matter, including PM2.5 and
• Carbon monoxide
• Sulfur dioxide
• Nitrogen dioxide
Pollution levels are predicted based on wind and weather forecasts. The AQI scale
runs from 0 to 500. The higher the AQI value, the greater the level of air pollution,
and the greater the health concern. For example, a red alert would go into effect if
there is a prediction that the air quality index will stay above 200 for more than 72
The color levels, index, and levels of health concern for ozone and particle pollution
• Green: Good, 0 to 50, Air quality is satisfactory, and air pollution poses little
or no risk.
• Yellow: Moderate, 51 to 100, Air quality is acceptable. However, there may
be a risk for some people, particularly those who are unusually sensitive to air
• Orange: Unhealthy for Sensitive Groups, 101 to 150, Members of sensitive
groups may experience health effects. The general public is less likely to be
• Red: Unhealthy, 151 to 200, Some members of the general public may
experience health effects; members of sensitive groups may experience more
severe health effects.
• Purple: Very Unhealthy, 201 to 300, Health alert: The risk of health effects is
increased for everyone.
• Maroon: Hazardous, 301 and higher, Health warning of emergency
conditions: everyone is more likely to be affected.
This blog presents opinions and ideas and is intended to provide helpful general information. I am not engaged in rendering advice or services to the individual reader. The ideas, procedures and suggestions in that are presented are not in any way a substitute for the advice and care of the reader’s own physician or other medical professional based on the reader’s own individual conditions, symptoms or concerns. If the reader needs personal medical, health, dietary, exercise or other assistance or advice the reader should consult a physician and/or other qualified health professionals. The author specifically disclaims all responsibility for any injury, damage or loss that the reader may incur as a direct or indirect consequence of following any directions or suggestions given in this blog or participating in any programs described in this blog or in the book, The Building Blocks of Health––How to Optimize Your Health with a Lifestyle Checklist (available in print or downloaded at Amazon, Apple, Barnes and Noble and elsewhere). Copyright 2021 by J. Joseph Speidel.