as shown in fig1 through 6 the inventive respiration hood assembly , generally designated by the numeral 10 , includes a molded plastic cap - like head piece 11 defined by a hemispherical cap or bowl 12 conformed to the skull dimensions of an adult person surrounded about the periphery of its opening by a generally circular brim 14 that extends eccentrically therefrom to deploy a forward portion 14 a overhanging the person &# 39 ; s face . the peripheral edge of brim 14 is rolled over to form a downwardly directed edge 15 supporting on its exterior an adhesive strip 16 to which the interior edge surface 21 of a flexible plastic membrane skirt 20 is adhered . in this form the head piece 11 once positioned on the head of a user deploys skirt 20 adhered to the peripheral edge 15 of brim 14 to drape over the back of the user &# 39 ; s head , his or her shoulders and in spaced relationship in front of the user &# 39 ; s face to then drape his or her chest , thereby providing a shrouded breathing space bc in front of the user &# 39 ; s mouth and nose . this breathing cavity bc is ventilated at positive pressure by a circular fan 17 supported for rotation within a circular opening 14 b formed through portion 14 a and engaged to the output shaft 18 a of an electric motor 18 fixed on posts or spacers 19 above the brim surface . the electric motor 18 , in turn , is powered by a battery 13 deployed on the back exterior surface of bowl 12 connected in parallel with a power cord 13 a terminated for contact within a conventional cigarette lighter cl found in most motor vehicles . in this manner a continuous flow of air is delivered into the breathing cavity bc , drying and transporting away any moisture that may be emitted in the course of breathing to accommodate a clear view through a transparent viewing section 22 in skirt 20 which may be further protected against accumulation of obscuring dust on its exterior by a plurality of stacked , peelable films 23 - 1 - 23 - n positioned thereon . in this form the combination of the skirt 20 and the head piece 11 provide a shroud over the upper body of a person ventilated to positive pressure by the fan driven air flow af right over the person &# 39 ; s face . any exit apertures that may be formed in the course of draping between the person and the lower skirt edge 25 will then be effectively emitting an outwardly directed stream of air , limiting all incidents of reverse ingestion of gas or air borne particulate matter . thus only the air intake into fan 17 needs to be filtered and otherwise sanitized to protect the person that has donned this inventive shrouding structure , a filtering function contained in a mating dished exterior cover 31 provided again with a generally circular brim surface 34 surrounding a housing 32 . brim surface 34 includes its own downwardly directed peripheral edge 35 dimensioned for receiving engagement of edge strip 15 with the skirt 20 adhered thereto . the upper portion of housing 32 is then provided with a generally rectangular cut - out 36 bordered by a recessed ledge 37 for supporting the edges of a rectangular filter element 38 thereon . a removable louvered cover 41 fixes the filter in place , admitting air into the housing interior through a set of louvers 42 that are each formed to define a saddle surface for convenient shedding of any particulates that may be collected on the housing exterior . those skilled in the art will appreciate that any terror event will invariably entail a wide particle size distribution , some particles approaching the dimensions of an aerosol while others of a mass to surface ratio that effectively limits any persistent air borne propagation . since both particle ranges pose a hazard when accumulated , substantial improvements are achieved if the larger , more massive particles are shed before being trapped in the filter . for this reason a smooth exterior finish is provided to the dished cover 31 and to also to the surface of louvered cover 41 . similarly , skirt 20 may be formed of a smooth plastic sheet material to promote shedding of any air borne particulates . the collection and entrapment of the smaller , aerosol sized particulates , in turn , is improved by selecting an inexpensive open brush direct current motor configuration for motor 18 which in the course of its use produces an arcing ring . motors of this type are generally less expensive as this commutator arcing is generally not desired because of the electrical noise that is usually created thereby . this arcing ionization , however , is used to advantage here by producing an electrostatic charge within the housing 32 which assists in the collection and entrapment of the small particles in filter 38 . the foregoing nested arrangement of brim 14 within brim 34 is also useful to trap and retain other supporting structures between the opposed brim surfaces , expanding the utility of the inventive assembly . for example , a flexible panel 51 provided with an edge bead 52 may be retained between the rear portions of the exterior brim surface 34 and the subjacent surface of brim 14 with bead 52 captured in their common folds . as result a curved form is imparted to panel 51 increasing its stiffness and utility as a supporting structure . a set of clips 53 - 1 through 53 - n at the other peripheral edges of panel 51 can then be utilized to fasten the combined structure to the adjacent folds of any apparel ap worn by the user , thus positively securing the inventive respiration hood to the person of the user , or as illustrated in detail in fig4 , securing the hood assembly 10 over a crib or infant seat assembly ia . notably , the capture of panel 51 can be selected by the user to be on the exterior of skirt 20 , or on the skirt interior ( not shown ), where the clips and fasteners thereby provided can be used for other manners of attachment such as those that may need to be effected to provide a respiration shield for a wounded or incapacitated person . one will appreciate that any significant terror event will invariably result in substantial public confusion and disruption of the ordinary routes of replenishment and supply . any protective device , and particularly a device that seeks to shield critical life functions like respiration , will therefore need to be quite robust and susceptible to refurbishing or renewal by ordinary and widely available means . thus while a sufficient supply of filter elements 38 may be included with the hood assembly for an anticipated exposure duration , in a setting where these exposure periods are exceeded , coupled with the need to frequently discard and seal the filter elements because of the hazard of the matter collected therein , alternative filtering mechanisms may need to be substituted to extend the needed shielding duration . in these extended eventualities some filtering degradation may need to be accepted and items of ordinary use , like paper napkins pn , may then be inserted and captured between the inner head piece 11 and the exterior housing 31 , either in conjunction with the filter elements 38 or as its replacement . similarly , ordinary plastic sheeting , trash bags or other membranes may be substituted as the material forming skirt 20 in those instances where the original material is torn or otherwise damaged . in this manner the nested and interlocked arrangement between the brims of the interior head piece 11 and the exterior housing 31 offers wide levels of utility over extended periods of time and significant levels of degradation and it is exactly this kind of resilience that is needed in the exigent circumstances of a terror event . obviously , many modifications and variations can be effected without departing from the spirit of the invention instantly disclosed . it is therefore intended that the scope of the invention be determined solely by the claims appended hereto .
a respiration hood assembly is effected from a thin - walled headpiece nested within the periphery of a mating exterior housing that includes a filtered aperture . the nested engagement between the headpiece and the housing is also useful in capturing one edge of a plastic membrane skirt that is thus suspended to drape over the person wearing the headpiece . a battery powered electric fan is deployed within the housing to draw ambient air through the vent aperture into the space shrouded by the skirt . the nested headpiece arrangement is useful in retaining other fibrous towels or tissue to extend the usefulness of the assembly and a parallel connection is provided to a motor vehicle battery to extend the period of electrical excitation .