Which of the following will NOT protect against brief exposure to dangerous gases or fumes? supplied air mask

full facepiece mask with chemical canisters

half mask or mouthpiece with a mechanical filter

self-contained breathing apparatus​

A. describe the model of urban structure most often observed in mega-cities in developing countries. explain how this model differs from common urban structures in north america. b. describe at least two factors leading to the growth of mega-cities in developing or least-developed countries. c. identify and explain two factors that led to the formation of squatter settlements in mega-cities in developing countries.