Anyone with lung or heart problems is being advised to take caution.
A public health alert has been issued as a result of air pollution in the midlands.
The Environmental Protection Agency has recorded air quality levels as being poor or very poor in several towns in the region.
It says it's likely due to the burning of fossil fuels and recent cold, calm weather which keeps any air pollution closer to the ground.
Dr Anne-Marie Murray, Specialist Registrar in Public Health Medicine is advising anyone who suffers from lung or heart problems to take caution: