First conditional

the possibility of harm or injury

a big amount of dirt — either in the air, water, or on the ground — that can be harmful or poisonous

connected to the environment, for example "environmental situation", "environmental studies" 

a big amount of dirt — either in the air, water, or on the ground — that can be harmful or poisonous 

the possibility of harm or injury

make the water, air or/and ground dirty with harmful or poisonous substances 

keep safe from harm or injury 

take the material you no longer need and use it to make another material you need 

start using less of the material you do not really need and take only what you need for living

use something again more than once 

start using less of the material you do not really need and take only what you need for living 

take the material you no longer need and use it to make another material you need 

don’t protect; disappear

won’t protect; will disappear

not protect; will not disappear

don’t protect; will disappear

will sort; will help

sort; will help

don’t sort; help

sorted; will help

will get; stop

gets; won’t stop

will get; don’t stop

will get; won’t stop