Treatment of whole houses with liquid nitrogen for control of dust mites.
A large volume of liquid nitrogen, (120-150 L) was applied to the houses of 4 asthmatic patients, and the mite densities of the floor dust from these houses were monitored every 2 wk for 4 mo from July to November 1989. The 1st liquid nitrogen treatment was applied in early August and decreased the mite densities to 20-44% of the pretreatment level in all cases, but they returned to the pretreatment level 3-4 wk later (on 3 occasions). The 2nd liquid nitrogen treatment was applied in early September and decreased the mite densities to 6-27% of the pretreatment level within 3 wk in all cases. However, mite numbers again increased to the pretreatment level 4 wk after treatment. The 3rd treatment was applied in mid-October and reduced the mite densities to < 6% of the pretreatment level within 2 wk, and mite numbers remained low thereafter. The results suggested that using liquid nitrogen to freeze houses reduces mite numbers, but that mite recolonization of the houses is an important problem.
Shibasaki
M
M
Department of Pediatrics, University of Tsukuba, Japan.
Ikeda
H
H
Isoyama
S
S
Imoto
N
N
Takeda
K
K
Noguchi
E
E
Takita
H
H
D000818:Animals; D008925:Mites; D009584:Nitrogen; D011156:Population Density; D013983:Tick Control
D009584:Nitrogen