Public Health

Public Health Researchers use Photo Mapping to Analyze Tobacco Ads near Schools

Photo mapping, a process in which geotagged photographs are accurately placed on a digital map, is often used by public health researchers to graphically track the spread of disease within or across a geographic area. In 2007, Public Health officials in Greece applied the same technique, to map tobacco advertising near public schools. Equipped with GPS-Photo Link photo mapping software and a GPS-enabled Ricoh camera, the officials documented in dramatic, yet unbiased, fashion the prevalence of cigarette ads in school neighborhoods. Their photographic and map-based reports were provided to the Greek government in 2009 as it considered and ultimately adopted strict new regulations on tobacco advertising.


The tobacco-use statistics in Greece are grim. The nation has the highest per-capita consumption of cigarettes in the world, and nearly 40 percent of its adult population smoke. Even worse, running counter to trends in many nations is the fact that Greek women are almost as likely to use tobacco as men. And these statistics were only expected to get worse in the future unless steps were taken to reverse the trends.

“The research [relating to tobacco use among] younger ages is 15 to 20 percent in rural areas to 50 percent in urban Athens,” said Constantine Vardavas, a Public Health Researcher at the University of Crete. “These trends have been increasing over the past years.”

Although Greece joined many developed countries years ago in banning tobacco advertising on television, on the radio and in print, it continued to allow nearly unregulated advertising on outdoor billboards and at points of purchase (POP) until sweeping new laws went into effect last year. These new regulations also put in place a minimum legal age for the purchase of tobacco products, which remarkably hadn’t existed until 2009.

Many factors have been shown to influence if and when children will experiment with tobacco, explained Vardavas, and advertising is one of them. Research has demonstrated that a higher exposure to tobacco advertising leads to a greater likelihood that a child will experiment with lighting up. With this in mind, Greek public health officials decided to employ state-of-the-art geospatial mapping technologies to determine just how many ads middle and high school students were exposed to while walking to and from school or playing outside at recess.

Mapping Photos

In the fields of epidemiology and public health, GIS has become a technology commonly relied upon in attempts to track and contain disease. Not only can the digital map be used to graphically represent the spread of a disease to determine where the next outbreak might occur, the technology can also be helpful in identifying clusters of disease in hopes of pinpointing the root cause. In the case of environmentally related illnesses, correlations can be drawn between levels of exposure and severity of sickness.

Photo-mapping has emerged as an important complement to GIS in numerous applications where a GPS-stamped photograph can be used to visually capture the condition of an object, or even its mere presence, and accurately tie this information to a location and time. Police use it to gather evidence, utilities rely on it to inventory assets, and local governments use it to assess regulatory compliance. And in an application such as this one in Greece where the main goal was to raise public awareness, the geotagged photo on a map carries the extra dramatic weight of a ‘picture is worth a thousand words.’

“Photo-mapping provides concrete evidence,” said Vardavas.

Through his position at the University of Crete, Vardavas had developed close ties with colleagues at the Harvard School of Public Health where photo-mapping had been used in a small tobacco advertising control pilot a few years -earlier. Having visited Vardavas in Crete, the U.S. officials agreed the technique could be used with dramatic impact in Greece where cigarette ads were far more plentiful.

“We use the GPS technologies to document the proximity of tobacco advertising near schools and playgrounds to create science that can influence policy,” said Professor Greg Connolly of the Harvard School of Public Health. “It’s an approach that uses high technology in a low-budget manner.”

For the Greek project, the Harvard health officials recommended using GPS-Photo Link software from GeoSpatial Experts of Thornton, Colo. This software automates the process of mapping geotagged photographs and offers the option of mapping them either to a GIS layer or Google Earth map. In addition, this software was designed to work directly with the Ricoh 500SE, the first digital camera designed specifically for GIS data collection. The Ricoh was also the only camera on the market at the time with an attachable GPS module for automatic stamping of location coordinates on each photo.

Mapping Tobacco Ads

Vardavas’ University of Crete office is located in the city of Heraklion, and it was considered ideal for the photo-mapping survey because it is representative of a typical Greek city with many schools packed into its urban center. With a population of 130,000, Heraklion is the fourth largest city in the country. Ten school complexes, educating more than 7,000 adolescent students (12-18 years in age) are situated within the city’s walls.

At the time of the project in summer 2007, nearly all outdoor tobacco advertising existed in the form of large billboards either mounted on the tops or sides of buildings. Some also adorned bus stops. In addition, cigarette ads of varying sizes were plastered on nearly every vertical surface, both inside and outside, of points of sale (POP). Most POPs were either convenience stores, which sell a variety of goods, or free-standing kiosks on the sidewalks. While some sell candy and newspapers, these kiosks exist primarily to sell cigarettes and account for the lion’s share of tobacco sales in Greece.

At the start of the survey, Vardavas and his team first recorded the GPS locations of each school in Heraklion, posted their locations on a Google Earth image of the city and drew 300-meter circles around each complex. The concept was to map every tobacco ad and POP within 300 meters of each school under the assumption that these ads were most likely seen by the majority of students driving or walking to school or could be viewed from the school property itself.

On the days of the survey, the researchers started at a given school and walked all streets within the 300-meter circle. They photographed every POP and outdoor tobacco billboard ad and recorded their locations with the GPS camera. As part of the survey, the researchers also went into POPs, such as convenience stores. Because they could not take photos inside these establishments, they attempted to count advertising posters and stickers, but this was sometimes an impossible task given the fact that some stores were literally wall-papered with cigarette advertisements.

The process of taking the photos was very quick, said Vardavas. “It generally took less than a day per school.”

At the end of the day, the team uploaded the photos and GPS points from the Ricoh into the GPS-Photo Link Software. It correlated the photos with their locations and mapped the position of each photo as an icon on the Google Earth layer. Flag icons represented billboard or bus stop ads, while Pushpins denoted POP establishments. School grounds were indicated by red polygons. By clicking on any of these mapped icons, the researchers could access and view the photograph it represented.

Beyond the dramatic impact of visualizing the density of ads around schools, Vardavas explained the photo mapping technique enabled them to analyze and quantify the concentration of tobacco advertising in a scientific manner from both the macro and micro levels. By viewing the icons posted in Google Earth, they were able to count individual sources of advertising and points of purchase around each school. These totals were carefully tabulated.

The researchers could then take this study to the micro-level by clicking on each icon to view the photo of a specific store or kiosk and count the total number of advertisements on that establishment alone. The photos also enabled them to make observations about the type of advertisement present in the POP as well as its height above the ground, which is considered a crucial factor in ad-targeting of young people. This information was also recorded in tables.

By combining their written notes with the mapped advertising data, the researchers accurately characterized the density of ads and POPs around schools and then measured the intensity of advertising inside the nearby POPs. The results showed that each school in Heraklion had an average of 13 POPs and 4.4 billboards or bus stop signs within 300 meters of its gate. Remarkably, every school had at least one POP, usually a kiosk, within four meters of the entrance. Most of the POPs had five to eight exterior advertisements on the outside and up to 25 inside the store. The majority of the interior ads were at or below a child’s eye level.

Vardavas quantified the results of the photographic analysis and field surveys, concluding that Heraklion does indeed have a high concentration of tobacco advertising in the immediate vicinities of its schools. He and his team packaged the results in the form of a dramatic Google Earth map and tabular ad counts into a written report, which was supplied to the government of Greece in 2008 as it considered its massive changes to tobacco advertising and sales laws.

Use of the GPS camera and photo-mapping software expedited the entire survey project in at least two ways. First, the outside data collection process was accelerated because most of the information was captured by the camera, allowing the researchers to peruse the photos in the office and tabulate the data at their leisure without being hurried by outdoor weather or traffic conditions. In addition, the photos gave the researchers the uncommon ability to revisit the images later to examine other variables that they may not have considered important until after the project had begun. No expensive return trips to the field were needed.

The Next Steps

Vardavas and Harvard’s Connolly both agree the photo-mapping technique has potential applications beyond influencing public policy. With the outdoor advertising ban now in effect, the process can be used as a compliance measure to flag advertisements that violate the regulations. The photographs may also be used to document new forms of advertising that crop up in an attempt to skirt the ban.

Looking into the future, Vardavas expects to see more use of photo-mapping technology in the public health arena, especially in tracking exposure to environmental pollutants. “This methodology is relatively inexpensive, and limited training is needed,” he said. “The software and GPS camera are easily available.”

Experts in geotagging technology expect it to be used in other public health applications including tracking alcohol advertising and studying environmental conditions around schools, parks and neighborhoods.

Further Reading – To learn more about this research project, please read the journal article, “Geographical Information Systems as a Tool for Monitoring Tobacco Industry Advertising” written by Constantine Vardavas and Gregory Connolly. It is available by clicking here.