Manhole npog tsis yog tsuas yog npog rau txoj kev hla, tab sis kuj ua haujlwm ntau yam:
Kev Tiv Thaiv Kev Nyab Xeeb: Tiv thaiv cov neeg ua haujlwm lossis cov khoom txawv teb chaws los ntawm kev poob rau hauv qhov av.
Environmental Isolation: Ua kom ruaj khov ib puag ncig hauv qhov av, tiv thaiv kev nkag mus ntawm cov dej nag, plua plav, thiab lwm yam.
Kev Kho Kom Zoo: Cov qauv tsim yuav tsum ua kom yooj yim qhib, ua kom ceev ceev rau cov neeg ua haujlwm tu.
