Pollen and mold reports are used for the diagnosis, treatment and management of allergic diseases. They are able to determine the amount of tree pollen, grass pollen, weed pollen and mold spores currently in the air at a specific location. These levels are indicated by a number representing the number of particles (pollen grains or mold spores) per cubic meter of air in a 24-hour period.

Pollen and mold counts are determined through an extensive network of counting stations that use air sampling equipment to collect airborne pollen particles and mold spores. These sampling devices usually use a sticky, transparent surface to capture individual pollen and mold spores floating throughout the air. Once particles have been captured over a 24-hour period, the sample is examined under a microscope where the individual grains or spores can be counted. Samples are generally collected three times a week.

Pollen and mold spores are small enough that they are typically distributed throughout a large area by air currents. For this reason, a single counting station is usually adequate to determine the pollen and mold counts for a wide area – often a whole city or community. However, pollen counts can still vary significantly over even a small area due to local factors.

The mold report is based on exposure to outside air and should not be applied to indoor conditions. Indoor molds often represent a completely different set of spore types.

The Aeroallergen Network is one of the most accurate and well-known reporting systems, and is used by the National Allergy Bureau (part of the American Academy of Allergy, Asthma and Immunology [AAAAI]). This network uses approximately 85 different counting stations located throughout the United States as well as three in Canada.

The Aeroallergen Network’s counting stations are staffed by AAAAI member volunteers. These volunteers are required to take a certification test and demonstrate their ability to calculate pollen or mold counts correctly.

The National Allergy Bureau’s pollen and mold report can be accessed by calling 800-9-POLLEN, or on the Internet at: http://www.aaaai.org/nab.

Oftentimes two different sources will report conflicting pollen or mold counts. There are several reasons why this may occur:

• Human error. Because each individual counting station relies on humans to view and interpret data, errors can occur in reported pollen and mold counts. These errors are common, though usually very slight.
  
  
• Sampling locations. Sampling devices used by the different counting stations can report slightly skewed results based on their specific location. A sampling device located under a single pollinating tree, for instance, is likely to show a higher pollen count than is actually represented by the rest of the surrounding area.
  
  
• Different types of particles. Some pollen and mold reports refer to the total number of pollen particles or mold spores in the air. Other reports only take into account the number of allergenic pollen particles or mold spores in the air, and do not include particles that are not usually associated with allergies (e.g., pine tree pollen).
  
  
• Type of sampling device. There are several different types of sampling devices available for determining pollen and mold counts. Using two different types of device may return different results even if used in the same area (see Types of sampling equipment).
  
  
• Pollen booms. Some trees and plants pollinate in sudden booms, sending pollen counts soaring for several days. These elevated levels of pollen can overwhelm some types of air sampling devices, leading to inexact pollen counts.

In addition, samples taken at different times of day can cause a disparity between two counting stations in the same city. For instance, pollen concentrations are typically highest in the morning. Therefore, a pollen sample taken later in the day may be considerably lower. A change in temperature, wind conditions, humidity or precipitation can also affect allergen levels.