There was also a danger that particles would enter the food chain or water.

These particles enter the air of the work area and can lead to silicosis in the workers.

These particles, when they are high enough, enter a colder band of air.

Soon more particles entered, all around the door frame.

Due to their small size, hot particles maybe swallowed, inhaled or enter the body by other means.

For a closed system, no particles may enter or leave, although they may combine in various ways.

The interior of the car was growing darker as more and more particles entered.

It also has limited usefulness if a system is open to the environment, because particles might coherently enter and leave.

As the solution travels down the column some particles enter into the pores.

These particles can embed themselves deep in the lungs and occasionally enter the blood stream.