What kind of monitoring is the most efficient in detecting the levels of dust in the equine respiratory system?
Filter based monitoring involves a sample of the environment being taken and then compared to a pre-weighed filter. A min, max and mean are collected-however it is difficult for the environment to be examined over a prolonged time frame or to collect enough samples to allow for contamination and environment changes over a day.
Real-time monitors can detect short-term rises in RDC, for example when a stable is mucked out. Clements and Pirie recommended the DustTrak™ 8520 to monitor intake of particles. Air is drawn through a cyclone which classifies particles according to size and a laser is then passed through the aerosol to count particles. The machine has a timer allowing for monitoring taking place over set times and for remote sampling. No significant difference was found between the mean of dust found using a filter system and the DustTrak™ 8520 monitor.
This is in contrast with Chung, who found the DustTrak™ 8520 underestimated dust content. Clements and Pirie hypothesize this is due to the DustTrak™ 8520 not recognizing particles under 0.1um. Pirie et al., found that most particles in horse stables were between 2.4-6um, thus quantities of particles less than 0.1 um are presumed as minimal. The DustTrak™ II Aerosol Monitor 8530, however now can recognize particles to the lower limit of 0.001 um. There may be scope in the future for stables to have individualized environmental monitors so that managers can oversee particulate level, however currently monitors are cost prohibitive and have short battery life and therefore are not financially or practically feasible for most trainers.
BZ monitoring is the most effective method of estimating the levels of dust inhaled by the equine. However, it could be argued that the mounting of a machine on a horse’s back may influence the equine’s stabled behavior. As monitors are becoming smaller such as handheld DustTrak™ II Aerosol Monitor 8532 (measuring (12.5 x 12.1 x 31.6 cm, 3.3 lb (1.5 kg) with battery) the likelihood of monitoring using the BZ less invasively is becoming more viable.