Pollution watchdog group Airparif said that the smog levels hit the top of its own 10-point scale on Wednesday for the second consecutive day across a number of French regions.
The country’s northern and eastern regions have been particularly hard hit by pollutants, prompting some organisations to pursue legal action to help curb air pollution.
Health officials warned vulnerable people — such as the elderly, children, asthmatics and people with heart problems — could experience laboured breathing and cautioned against spending too much time outdoors.
A number of recent reports have linked elevated levels of air pollution to reduced life expectancy and low birth weight among babies, and in October a branch of the World Health Organisation officially classified particulate matter as carcinogenic.
High smog levels usually require a reduction in vehicular speed, a ban on fires and health recommendations such as limited physical activity and avoiding walks outdoors for children under six years old.
Three organisations dissatisfied by the government’s response are lodging unprecedented lawsuits this week in an effort to spur leaders to take bolder steps aimed at reducing air pollution.
Paris police lowered the speed limit for cars to 20 km/h in some areas and banned trucks weighing over 3.5 tonnes from entering the city after a peak in air pollution in December 2013.
The French government also tabled at that time a possible bill that would require drivers to alternate the days in which they were allowed to drive based on license plate numbers.