El número límite para indicar que el aire de una ciudad está contaminado es de 10 pm2.5. sin embargo, méxico d. f. tiene un índice de contaminación de
2.5 pm2.5
5 pm2.5
25 pm2.5
100 pm2.5

when the outside temperature is too cold, an endothermic animal can generate heat by shivering. endothermic animals must eat much more often than ectothermic animals since it takes energy to maintain a constant body temperature.