Evaluation of Thermal Foggers of Public Health Network Agencies, Vector-Borne Disease Control Center 6.5 Chanthaburi Province

Abstract

Aedes mosquito control can be implemented through various approaches; however, during outbreaks, space spraying of adulticides remains an important measure for reducing disease transmission. This descriptive study aimed to evaluate thermal fogger standards, compare chemical droplet quality according to fogger characteristics, and describe the characteristics of foggers that failed the Volume Median Diameter (VMD) criterion. A total of 131 thermal foggers submitted for evaluation at Vector-Borne Disease Control Center 6.5, Chanthaburi Province, between February and May 2026 were included. The proportions of foggers meeting the VMD criterion (≤30 μm) were 86.21% in Chanthaburi and 81.82% in Prachinburi. All foggers in both provinces met the droplet uniformity criterion (Span < 2.0). The proportions meeting the chemical flow-rate criterion were 71.26% and 70.45%, while those meeting the nozzle-temperature criterion were 96.55% and 100%, respectively. The Kruskal–Wallis test showed that VMD differed significantly across fogger brands (H = 15.99, df = 8, p = 0.043); however, Bonferroni-adjusted pairwise comparisons showed no significant differences between individual brands. VMD also differed significantly according to nozzle size (p = 0.003), with 1.4-mm and 1.2-mm nozzles differing significantly from foggers without a fixed nozzle. Service life and frequency of use were not significantly associated with differences in VMD or Span. Among the 20 foggers that failed the VMD criterion, 55.00% had been in service for ≥10 years, 55.00% were used 1–9 times per year, and 50.00% had below-standard flow rates. Therefore, flow rates and VMD should be routinely assessed, foggers should undergo standard evaluation before the outbreak season, and regular maintenance should be performed.