Mental problems can be triggered by many different factors, of course. Researchers underline that there is no direct 1 on 1 link between air pollution and mental problems at work. But what they do see, is that a poor air quality is an important trigger: when air pollution peaks, this has an immediate effect on the number of people seeking help with the doctor.
On days when particulate matter or black carbon levels were 0.5 micrograms per cubic metre up, the number of diagnosed cases rose by 3.5 percent, scientists found. When nitrogen dioxide levels rose by 5 micrograms per cubic metre, there was 4.2 percent more staff dropping out. The diagnosis was made on the day with the pollution peak itself, or up to two days afterwards.
"We are not saying that air pollution causes depression or burn-out. There are many more factors involved", says Luk Bruyneel, one of the authors of the study. "But a day with high air pollution levels can be a trigger, the straw that broke the camel's back."
"Fine particulate matter not only impacts on the lungs, but also on the brain", says professor Tim Nawrot. People that are mentally vulnerable, can get a depression or burn-out.
The Independent Health Mutuals are asking health ministers to do more to tackle air pollution in Belgium, and to support the new (stricter) guidelines of the World Health Organisation (WHO).