Allergy Handbook

Allergy and The Environment – An Arizona Handbook

The Arizona Allergy and Asthma Society is an organization comprised of board-certified and board-elligible Allergy/Immunology specialists in Arizona. One of our goals is to serve as a resource for allergy information to the Arizona public. This is achieved by providing Arizonians with the “Allergy and the Environment, An Arizona Handbook.” On online version of this handbook is available below.

Urban Environment

Does Urbanization affect Allergy?


Mark R. Sneller, Ph.D* Jacob L. Pinnas, M.D.

When there is growth in a community, it leads to a decrease in natural vegetation. Therefore, this process of urbanization can lead to a decrease in the level of aeroallergens such as occurs which natural forests are replaced by roads and buildings. However, city development can also result in an increase in the level of local aeroallergens when ornamental vegetation is added for landscape purposes for the comfort, convenience, and beautification of the urban environment.

The latter is precisely what has happened in the desert Southwest. This includes such cities as Phoenix, Tucson, Las Vegas, El Paso, and Albuquerque where the natural environment has been augmented by the planting of ornamental trees and grasses that also happen to produce allergenic pollen which is airborne. These trees include mulberry, olive, sycamore, ash, elm, poplar, mesquite, and cypress, as well as ornamental juniper.

It has been shown that the urban increase in aeroallergens appears to parallel the increase in human population. In the Tucson basin, allergenic tree pollen has increased more than twenty-fold over the past several decades. This led to the creation of a countrywide ordinance in 1984 (1984-29). This ordinance banned the sale and planting of olive and mulberry trees and ordered domestic Bermuda grass to be cut before it can pollinate.

For most of the cities mentioned, regulatory actions have already been put in place or are in the planning process. These regulatory actions are tailored to the specific plants and problems of that city. When successfully implemented, these bans forbid the planting of certain allergenic trees in newly developing areas of the city and forbid their planting in the existing city as well.

It is important to realize that the substitutes for banned trees may or may not be as allergenic. For example, South African sumac is a popular shade tree whose pollen may be less allergenic or less airborne when compared to many other trees. However, oak and the stately London plane trees produce extremely high levels of pollen that easily become airborne and be carried long distances. The pollen from these trees can be moderately or strongly allergenic.

In addition to the introduction of allergenic grasses and trees, the disturbance of natural land can lead to the spread of very allergenic weedy species in the urban environment. These species include various native and non-native ragweeds and numerous noxious weedy species belonging to the goosefoot and pigweed families such as Russian thistle, careless weed, and saltbush.

Date collected over many years also reveals an increase in mold associated with the increase in vegetation. For example, Alternaria, the most common allergenic mold, has increased almost tenfold over the past twenty years. This mold thrives on decaying plant material.

*Dr. Sneller is owner/director of Aero-Allergen Research, Tucson, Arizona.The monitoring of aeroallergens and public education are necessary to understand the impact of local vegetation has upon human health. In view of the high incidence of respiratory allergies and asthma in Arizona, twice the national average, exposure to a growing number of allergens may be a questionable tradeoff for shade.

What are the effects of Air Pollution on Allergy?


by Jim Chevalier, M.D.

Indoor and outdoor pollution is an increasing problem in society, and becomes especially important for a patient who has asthma. Maricopa county has the third highest death rate from asthma in the nation, and pollution likely contributes to the problem. A California study in 1993 showed a definite correlation between respiratory complaints and ozone/sulfate levels in the air. A 1993 study from Barcelona showed a similar relationship for sulfur dioxide and smoke. Recent studies also suggest that even very fine particles such as dust may aggravate breathing problems.

The single most important indoor pollutant is cigarette smoke. There is a very clear relationship between parental indoor smoking and childhood asthma severity. Children in a smoking environment have a 65% greater chance of developing asthma than in a nonsmoking environment. There is some evidence suggesting changes in embryonic lung development in babies whose mothers smoked during pregnancy or were exposed to smoke. Spouses of smokers are twice as likely to develop lunch cancer as spouses of nonsmokers. Other possible indoor triggers include cats, dogs, and dust mites.

There are some specific actions that patient with asthma or allergy can take to reduce their exposure to pollution and irritants in the environment:


  • Do not smoke in the household, even when the patient is out of the house. A totally smoke-free home environment will often have as much benefit as several medications.
  • Use air conditioning rather than open windows or evaporative cooling if possible, especially during the spring and fall pollination seasons or periods of heavy pollution.
  • Consider a HEPA filter in the bedroom or living room, or on a central air conditioning unit. Although most insurance plans will not cover a filter, it seem to dramatically reduce the indoor dust and dander concentrations.
  • Try to have as many bare surfaces in the bedroom environment as possible, minimizing heavy carpets, drapes, and stuffed animals. This will reduce the reservoir for dust, pollen and other triggers, and is surprisingly effective. Damp mop the bare floor frequently to keep the dust load down.


  • Stay indoors during pollution alerts.
  • Try not to exercise outdoors during times of heavy pollution and pollination. Pollen counts are often heaviest in the early morning.
  • Wear a face mask during periods of high pollination when you are outdoors, especially mowing or any other heavy exertion. Pollens generally are large and can be trapped by masks.• Use your automobile air conditioning with the windows rolled up, even on a cool day. This will dramatically reduce pollen and dust exposure. Set the air condition to recirculate cabin air (“Max A/C on many newer cars).

Environmental control is often ignored as a means of helping control asthma. Environmental control can often reduce the need for extra medications and reduce the severity of respiratory disease and allergies, but the benefits cannot be minimized.

What is the effect of air pollution in Phoenix?


by Geraldine Freeman, M.D.*

The Arizona Department of Environmental Quality, through a delegation from the U.S. Environmental Protection Agency, enforces the Clean Air Act (CAA) in Arizona. The CAA was enacted by Congress over 25 years ago to monitor air pollutants, gas and solid, and attempts to reduce these factors to quality standards. Monitored elements are nitrogen oxide (NO2), ozone (O3), sulfur dioxide (SO2), and particulates (PM10—particles 10 microns or smaller in diameter), all of which have important specific effects on the respiratory tract, some immediate and some long-term.

Pollution is generally worse in wintertime due to temperature inversions, with better months in spring and October associated with wind that moves the pollutants away. The Phoenix “valley” is actually a plain—lower, hotter, and more extensive than Tucson to the south. Cold, dry air, an irritant for asthma, is less problematic than in many parts of the U.S. because of mild winters.

Most air pollution in Phoenix is produced from motor vehicle emissions. Carbon monoxide (CO) affects the oxygen-carrying capacity of blood and the cardiovascular system. SO2 from coal and oil burning and copper smelters (some distance from Phoenix) provokes asthma when breathed through the mouth. Ozone forms from photochemical reactions, primarily on nitrogen oxides and hydrocarbons from vehicular exhaust and industrial combustion, the latter minimal in Phoenix. The sunshine and hot temperatures of the summer (up to 115°F) make ozone a particularly tenacious summer problem. CO levels have improved whereas O3 levels have risen. Particulates include dusts and hydrocarbons. Brown haze is associated with particulates and NO2.

Overall, pollution levels are in a holding pattern in the Phoenix area long-term as the population using vehicles grows rapidly in a city without much progress in providing alternate transportation within it’s increasingly sprawling borders. Oxygenated fuels are required, and cars must be emission certified.

Allergists believe that asthma and allergic rhinitis are increasing worldwide. Both monitored and non-monitored airborne factors may be important causes. Research in the Los Angeles area has identified airborne diesel and gasoline exhaust products as well as plants debris, wood smoke, charbroiled meat smoke, paved road dust, and rubber particles. Rubber and plant fragments are allergenic. Research laboratories have identified multiple immune-allergic responses to diesel exhaust particles which may prove important. While individual diesel particles are minute they can aggregate to a size that will deposit in the human airway.

*Mark R. Santana, Administrative Counsel for the Arizona Department of Environmental Quality, provided air quality data and helpful advice.

What is the effect of air pollution in Tucson?


by Michael J. Schumacher, M.D.

Metropolitan Tucson is surrounded by mountains, predisposing the area to frequent temperature inversions. During this time the valley fills with colder air containing higher concentrations of air pollutants, as compared with mountain slopes above the temperature inversion layer.

Local sources of air pollution are traffic (greater than 40%), vehicle-generated paved road dust (12%), and dust from unpaved roads (8-10%). Pollution from automobile emissions (mainly nitrogen dioxide) increases in the winter, particularly on days with temperature inversion. As in other cities, use of oxygenated motor fuels contributes to aldehyde and other volatile organic compound pollution.

The average concentration of ozone in the city ranges from 0.022 to 0.042 ppm (parts per million) throughout the Tucson basin, and is tending to increase. Highest levels of ozone generally occur in the summer. Average concentration of nitrogen dioxide range from 0.019 to 0.021 ppm, and particulates 10 microns and smaller range from 12.5 to 30.7 micrograms per cubic meter. Aside from a coal- fired power plant, Tucson has no heavy industrial sources of sulfur dioxide and levels of this pollutant are low.

Symptoms of asthma and other chronic lung diseases are precipitated by increased levels of air pollutants including nitrogen dioxide, ozone, and particulates, and the increased incidence of asthma in the fall and winter may be related to effects of temperature inversion on vehicle-generated pollution. Air pollution in Tucson may also influence the high incidence of allergy in this region, but further research is needed to confirm this.

Allergy and the Environment