Dosimeter construction

A dosimeter for detection of noxious substances including a substrate collection carrier on which the substrate is collected and a diffusion membrane, formed by the steps of:

• subjecting the substrate collection carrier to compressive stress;
• placing the membrane over the substrate carrier;
• securing the membrane and the substrate carrier about a marginal region;
• and, applying pressure to a side of the substrate carrier opposite to the overlayed membrane to form a curved shape thereby placing the membrane under a uniform tension to uniformly fit the membrane over the substrate carrier without creating folding areas or buckling areas.

A dosimeter for detecting of noxious substances comprising:

• a housing having a first housing part and a second housing part said first and second housing parts cooperating to define a chamber, said first housing part having an inlet opening;
• a substrate carrier;
• a colorimetric indicator layer positioned over said substrate carrier;
• a gas permeable diffusion membrane positioned over said colormetric indicator layer, each of said substrate layer, diffusion membrane and colorimetric indicator layer being positioned within said chamber and having a marginal area positioned between said first housing portion and said second housing portion, said substrate carrier being curved in a direction of said inlet opening such that said gas permeable membrane abuts said colorimetric indicator layer which abuts said substrate carrier such that said diffusion membrane hugs the shape of the curved substrate carrier.