San Jose, the capital city of Costa Rica greets tens of thousands of foreign visitors each week, but it does not even come close to the French capital of Paris, where more than 15 million visitors arrive each year. Aside from tourism, Paris and San Jose do not share much in common; however, some observers believe that San Jose is one of the most contaminated cities in the world in terms of air pollution. How does San Jose compare to Paris and other tourist destinations?

The Jamaica Observer recently published an Associated Press report on the dangerous levels of air pollution that Paris has been experiencing in mid-March:

The French Government will tomorrow introduce alternate driving days in Paris for the first time in nearly two decades to tackle dangerous levels of air pollution in the city.

The Government made the announcement after pollution particulates in the air exceeded safe levels for five days running in the capital and surrounding areas.

By yesterday the number of pollution particulates in the air had fallen slightly after hitting a high of 180 microgrammes per cubic metre — well over double the safe limit — on Friday.

These so-called PM10 particulates are created by vehicles, heating and heavy industry, with the safe limit set at 80 per cubic metre.

Indeed, the Air Quality in Europe real-time index for March 16 indicated that Paris was at 95 PM10 and more than 100 PM2.5 levels, which are considered to be very harmful for human lungs. PM2.5 particles are defined as:

air pollutants with a diameter of 2.5 micrometers or less, small enough to invade even the smallest airways. These particles generally come from activities that burn fossil fuels, such as traffic, smelting, and metal processing.

The problem with PM2.5 contaminant particles is that they tend to hang in the air for days, even weeks sometimes. In the past, the air in the lovable city of San Jose has been reported to have reached alarming levels of contamination, but never quite as high as Paris. As reported by the Costa Rica Star in August 2013:

The pollution in Costa Rica’s capital city, San José, is a threat to Costa Ricans’ health, a study by the Laboratorio de Análisis de Calidad de la Universidad Nacional (UNA) – National University´s Quality Analysis Laboratory has mentioned.

Harmful particles in the air were recorded at 37 micrograms per cubic meter (ug/m3), according to the research. The figure is almost double the maximum contaminant levels established by the World Health Organization (WHO).

While the high air pollution levels reported last year in San Jose are certainly worrisome, it helps to compare them with this 2013 list published by online news magazine Quartz, which puts San Jose at about the same level of air contamination as the agricultural region of Bakersfield in California.

The dirty air in Paris at this time is nothing in comparison to many cities in Asia and the Middle East. In Beijing, for example, PM2.5 readings higher than 100 ug/m3 are considered average; even avid smokers from Costa Rica would find the air of this Chinese metropolis uncomfortable to breathe.