The Meuse Valley Fog of 1930

J. Wagner


The Meuse Valley Fog of 1930 was a severe air pollution event that affected Liege and the surrounding area along the Meuse River in Belgium in December of 1930 (Nemery et al., 2001). Specifically, over the period of December 1st to December 5th, 1930, heavy smog was reported over the area, determined to be the result of both climate conditions and air pollution emissions from within the Meuse Valley (Nemery et al., 2001). 63 excess deaths were reported as a result of the event and marked one of the first significant air pollution events to demonstrate the potential of atmospheric pollution to cause death (Nemery et al., 2001).


Location and Sources of Pollution

The Meuse Valley is the region along the Meuse River between Liege and Huy, Belgium (Lipfert, 1994). In 1930, this 20 km stretch housed 27 factories established post-industrial revolution (Nemery et al., 2001; Lipfert, 1994). Such industries included zinc smelters, glass and steel manufacturers and explosive plants (Nemery et al., 2001). The sources of pollution within the Meuse Valley region were the result of both the densely populated factories along the Meuse River and the recent increase in population and subsequent increase in domestic coal burning (Nemery et al., 2001; Firket, 1936).

Weather Conditions

During the period of December 1st to December 5th, the weather was characterized as anticyclonic with high atmospheric pressure and low-speed wind blowing from the east (Nemery et al., 2001). In addition, temperature inversion occurred at approximately 90 yards from ground level within the valley, just below the hills on each side (Firket, 1936). Fallen fine solid particles were noted within the five day period, consisting primarily of soot and ranging from 1 to 4 microns in diameter as well (Firket, 1936). Periods of persistent fog were uncommon to the Meuse Valley region, with only five events of persistent fog greater than three days being documented (1901, 1911, 1917, 1919 and 1930) (Firket, 1936).


Starting the afternoon of December 3rd and onwards, hundreds of those residing within communities of the Meuse Valley exhibited severe respiratory symptoms. Specifically, the residents were experiencing laryngeal irritation, retrosternal pain, coughing fits and asthma-like symptoms (Nemery et al., 2001). In addition, some residents also experienced nausea and vomiting though no other symptoms which would point to poisoning (Nemery et al., 2001). 63 excess deaths within the Valley were reported by December 5th (Lipfert, 1994). Once the fog eased on December 6th, the experienced respiratory symptoms improved and no excess deaths were reported following December 5th (Firket, 1936). Effects were also visible in livestock, mainly cattle (Firket, 1936).


As a result, a public inquiry was launched with the resulted presented to the Royal Academy of Medicine of Belgium on May 19th, 1931 (Nemery et al., 2001). Medical data was obtained by interviewing those who had experienced respiratory symptoms, local physicians and family members of the deceased (Firket, 1936). Fifteen autopsies were completed, including tissue examination and toxicological analyses of all organs and blood (Firket, 1936). Local and superficial irritation of the mucous membrane was found, with all toxicological tests being negative (Firket, 1936).

Chemical analyses of soil deposits along the valley were completed to determine the composition of the fog, however the results could not be linked specifically to the fog (Firket, 1936). Analysis of the emissions from the factories along the Meuse River were also completed, showing concentrations of carbon monoxide, carbon dioxide, nitrous gases, sulphur dioxide and hydro-fluoric acid (Firket, 1936). It was also hypothesized that sulphur dioxide may have partly transformed to sulphuric acid due to the presence of oxidizing agents and moisture from the fog (Firket, 1936).

Based on the pathological evidence and emission analysis, it was concluded that sulphur dioxide was likely the cause of the symptoms experienced in the Meuse Valley area through a process of elimination (Firket, 1936). This was determined as the largest concentration of pollutant in the valley was sulphur dioxide, primarily due to the domestic burning of coal (Firket, 1936). Further analysis indicates sulphur dioxide concentrations within the Meuse Valley reached 25-100 mg/m3 (Mudakavi, 2010). In addition, it was calculated that sulphur dioxide was the only pollutant that could have dispersed throughout the valley in high enough concentrations to exhibit toxicity in humans (Firket, 1936). Furthermore, the weather conditions promoted the production of sulphuric acid which may have been responsible for some of the asthma-like symptoms (Firket, 1936). Therefore, it was determine that the event was not due to excessive sulphur dioxide emissions, but the combination of the sulphur dioxide emissions and meteorological conditions, stating that the event would occur again with the same activity levels and weather (Firket, 1936).


The Meuse Valley Fog of 1930 was one of the first major events that showed the potential link between morbidity and air pollution. In addition, the findings of the public inquiry showed the role of temperature inversion and fog in air pollution (Nemery et al., 2001). Finally, citing sulphur dioxide emissions from domestic coal burning as the primary source of the air pollution event combined with the meteorological conditions was a tale of caution to surrounding regions (Nemery et al., 2001). Specifically, Firket (1936) estimated that should a similar episode in London occur, it may lead to as many as 3200 fatalities.

As a result of the event, a commission was appointed to assess the current industrial air pollution legislation and to suggest improvements to prevent an event of similar magnitude from occurring (Nemery et al., 2001) It was recommended that Belgium monitor air pollution similar to Great Britain (Nemery et al., 2001). However, as translated by Nemery et al. (2001) it was ultimately agreed that air pollution was an unavoidable consequence of prosperity by Batta, Firket and Leclerc (1933). Following the Meuse Valley Fog of 1930, no air pollution events of a similar magnitude occurred in the Meuse Valley, though similar events occurred in Donora, Pennsylvania (1948) and London (1952) (Nemery et al., 2001).


Batta, G, J Firket and E Leclerc. Les problemes de pollution de l'atmosphere. Liege, 1933. Print.

Firket, J. Fog along the Meuse Valley. Transactions of the Faraday Society 32 (1936): 1192-7. Retrieved from:

Lipfert, F. W. Air Pollution and Community Health: A Critical Review and Data Source Book. New York: Van Nostrand Reinhold, 1994. Print.

Mudakavi, J. R. Principles and Practices of Air Pollution Control and Analysis. New Delhi: I. K. International Publishing House Pvt. Ltd., 2010. Print.

Nemery, B, P Hoet and A Nemmar. The Meuse Valley fog of 1930: an air pollution disaster. The Lancet 357 (2001): 704-8.