Developing Credible Data on Air Quality

Thursday, September 12, 2019
Good policy depends on good data. As cities and countries in the Americas tackle the problem of air pollution—a growing public health concern—they rely on air quality monitoring systems to measure how they’re doing. Through workshops co-sponsored by the Organization of American States (OAS), experts who operate such systems throughout the region are strengthening their expertise and cooperation to ensure that those results are accurate, reliable, and credible. That’s especially important when air pollution reaches a crisis point—as it did in Mexico City in May of this year.


It happened during the peak “ozone season,” a time of year when conditions in Mexico City typically cause elevated levels of the harmful pollutant, according to Olivia Rivera Hernández, Director of the city’s Air Quality Monitoring Network. Ozone is a “secondary” source of pollution, formed when volatile organic compounds and nitrogen oxides react with sunlight. High-altitude areas are particularly susceptible.

What was already a chronic problem was exacerbated in mid-May by major forest fires in neighboring states—a consequence of last year’s drought—and winds that blew the smoke straight through the metropolitan area, Rivera Hernández said in a phone interview. The resulting levels of fine particulate matter and ozone were unprecedented in the last 30 years, she said.

City, state, and federal authorities took steps to try to reduce exposure to the pollution—especially for children, who are most susceptible to harm. Classes for primary and secondary school students were suspended for two days, and measures were put in place to restrict the movement of vehicles.

Although the vehicle restrictions no doubt helped, much of the problem during those days had to do with fire and wind, not vehicles—but people don’t always understand that and instead tend to blame the government for not doing anything, Rivera Hernández said. “We can control some things, but we can’t control everything ,” she said.

Mexico City is hardly alone in having pollution problems. In June, on the eve of a Copa América soccer match in Santiago, Chile, residents were asked to forego barbecues on game night—one of a series of “pre-emergency” steps to counteract a bad-air day. In parts of China, air pollution blocks the sun so much that it has led to a drop in solar power generation, according to a recent report in the journal Nature Energy.

Meanwhile, the World Health Organization (WHO) has been sounding the alarm about the effects of air pollution, estimating that it causes an estimated 7 million deaths worldwide per year. More than half of all pneumonia deaths in children under age 5 are caused by air pollution, according to WHO, and early exposure is associated with an increased risk for many chronic diseases.

Against such a backdrop, it is critical for cities around the region to develop technically sound, credible systems for monitoring air quality. As Rivera Hernández put it, people need to know that the system works and that its results can be compared with those in the United States or Europe. “That gives an added value to the information we are providing ,” she said.


Sharing Information


A technical workshop held August 26-29 in Mexico City brought together experts on the front lines of monitoring air quality in nine countries in Central and South America, to share knowledge about how to make their systems more robust and accurate. This was the second such workshop held with the support of the OAS, through the Energy and Climate Partnership of the Americas (ECPA), and the U.S. National Institute of Standards and Technology (NIST); the first took place last year in Costa Rica. (See previous story, Putting Air Quality to the Test.)

Different cities in the region have different pollution problems—depending on their population, geography, elevation, and climate—and different levels of experience. The goal is to develop a broader, deeper knowledge across the region about how to set up an effective system for monitoring air quality, Rivera Hernández said.

Many variables go into the monitoring process, she explained: Where should the monitoring stations be placed to cover the most populated areas? What methodology is being used to measure the different pollutants? Is the methodology valid and the results comparable across countries? What measures are needed to ensure that the instruments are working properly and that any problems are detected quickly? Are the equipment suppliers reliable? Are the best calibration techniques being used? Is it possible to reduce the margin of error? The workshop in Mexico City included not just presentations but hands-on training with different types of equipment.

One possibility, going forward, might be to set up ongoing training through webinars and visits, in which cities with more experience can serve as hubs to disseminate technical information to other countries, Rivera Hernández said. For example, she said, São Paulo, Brazil, has even more air quality monitoring stations than Mexico City—something she was not aware of before last year’s workshop. Mexico City has been producing reliable data since 1986, she said, though its earliest air-monitoring efforts date back to 1950.

Information-sharing has been underway on an informal basis since the first workshop in Costa Rica. Participants from different countries found that they encountered many of the same challenges, and in some cases were even using the same equipment. They decided to keep in touch through a WhatsApp group.

María Inés de Casas, Deputy Chief of Operations at the Air Monitoring Network for the city of Buenos Aires, said the group has proved useful for solving technical problems—such as how to validate the methods used to measure fine particulate matter. In that case, she got help from a counterpart in Brazil who was using the same equipment and had already figured out a solution.

In another case, experts from several countries banded together to appeal to a supplier that was no longer providing parts for a piece of equipment it had discontinued. De Casas had been trying to get through to the company for two years with no results, but when she and her colleagues wrote a letter together—in other words, when 60 or 80 pieces of equipment were involved, not just a handful—they were able to persuade the company to keep supplying the parts for another two years.

That makes a huge difference when budgets are tight, as they are throughout the region, de Casas said. Having to replace a piece of equipment that simply needs a small part may mean not being able to expand the monitoring system that year, she explained. “There’s not enough money to do both.”

One of the most important objectives of these workshops, de Casas said, has been to ensure that experts across the region are speaking “the same language ”—in other words, that a particular measurement has the same objective value between one country and another. In the science of measurement, or metrology, that property is called “traceability .” Experts use different calibration materials and techniques to ensure that everyone is measuring against the same reference points.

While this may sound merely technical, it goes directly to policy, de Casas said. “If the diagnosis is accurate, the policies that go hand in hand with it will likely be more appropriate,” she said. “If I implement a policy to reduce carbon monoxide, for example, and I don’t have an accurate diagnostic source, I’m not going to know whether the policies I implement are truly effective.”

It was a point echoed by Tiberio Benavides, another participant from last year’s workshop, who coordinates the Air Quality Laboratory on the National University of Colombia campus in Medellín. Good data, he said, will enable governments to implement measures on such matters as gasoline standards, vehicle emissions, traffic patterns, and public transportation.

“It’s very important to do the measurement right to be able to make policy on air pollution for the city and improve the air that everyone breathes,” he said. “In the end, the aim is to inform the community about their quality of air.”