Dispersion of horse allergen from stables and areas with horses into homes.

This Swedish research article studies the dispersion of horse allergens from stables and other horse areas into homes and their indoor and outdoor levels according to their distance from these sources. The paper shows that allergen levels decrease quickly when the distance from horses or stables increases and the allergens are rarely found indoors in homes.

Research Goals and Methods

• The primary objective of the study was to investigate indoor and outdoor levels of horse allergen according to their distance from horse stables and tracks. The researchers undertook this project in response to a Swedish national report’s recommendation that a minimum of 500 meters should separate homes from stables or areas with horses to safeguard susceptible people from horse allergen exposure.
• To gather data, indoor and outdoor samples were collected using Petri dishes from 49 different sites, including different housing areas and a horse trotting track’s vicinity. For indoor samples, they placed the dishes on a bookshelf in the living room approximately 1.5 meters high. For the outdoor samples, they affixed cages with Petri dishes to tree branches at varying distances from the horse track.

Research Results

• Out of the 45 indoor samples collected, six had detectable levels of horse allergen. Notably, three of these instances occurred despite no family member having any previous contact with horses.
• Out of the 26 outdoor samples collected, 16 tested positive for horse allergens.
• The research found a significant decrease in allergen levels as distance from horse stables or tracks increased. For instance, the allergen level detected 45 meters away from a horse track was about 1% of the level detected just 1 meter away from it.

Conclusions and Implications

• The research concluded that allergens dispersed from horses decline considerably outdoors and are seldom found indoors in homes. This finding provides scientific evidence supporting the Swedish national report’s recommendation.
• The study further emphasizes that indirect exposure to horses, such as exposure from the clothing of horse riders, should also be considered for protective measures against undesired horse allergen exposures. This suggests that the allergy-inducing potential of horses extends beyond direct contact and can persist even at a distance or indirectly.