Battling Illness on Public Transportation

Spinella said research by oth­ers has sug­gested that buses, being enclosed pub­lic spaces, can pro­vide an envi­ron­ment for the spread of TB and other dis­eases. “These are closed spaces where peo­ple are in close prox­im­ity, and you have an active air-conditioning sys­tem that’s con­tin­u­ally mix­ing up the air and spread­ing it to all the pas­sen­gers,” he said.

The Rice project stemmed from the results of a study called the Houston Tuberculosis Initiative (HTI). Researchers worked from 1995 to 2004 to iden­tify pat­terns of trans­mis­sion in the region that—though the dis­ease is still rare—has the second-largest TB pop­u­la­tion in the nation. They were sur­prised to find a cor­re­la­tion between rid­ers of city buses and cases of tuber­cu­lo­sis. A study pub­lished last fall in the jour­nal Tuberculosis put num­bers to the risk by point­ing out that some routes, par­tic­u­larly long ones, indi­cated a higher num­ber of cases of the disease.

The lead author of the HTI study prompted the Rice project when she decided to act on the research results. “We found we had a prob­lem on the buses in Houston,” said Marsha Feske, a for­mer grad­u­ate stu­dent at the University of Texas Health Science Center at Houston and research fel­low at The Methodist Hospital Research Institute. She is now an epi­demi­ol­o­gist at the global bio­sciences com­pany Becton Dickinson. “Knowing Rice had some exper­tise in tuber­cu­lo­sis, I con­tacted Maria Oden to see if the uni­ver­sity could help.”

Oden, a pro­fes­sor in the prac­tice of engi­neer­ing edu­ca­tion and direc­tor of Rice’s Oshman Engineering Design Kitchen, pitched the idea to stu­dents look­ing for cap­stone design projects, which are required of all senior engi­neer­ing majors at Rice. Five took on the challenge.

With Feske, Oden and Rice bio­engi­neer­ing lec­turer Matthew Wettergreen as advis­ers and METRO staffers offer­ing tech­ni­cal help, the team came up with a stream­lined sys­tem that falls well within the abil­ity of a METRO bus to power it while sur­pass­ing even their own strin­gent require­ments that FluProof kill 99 per­cent of air­borne pathogens.

The CityBusters team installed a unit on a work­ing METRO bus and demon­strated it dur­ing the annual George R. Brown School of Engineering Design Showcase, held dur­ing Rice’s UnConvention open house April 12. “We have two lamps installed, one on each side,” said team mem­ber Lue as he stood at the back of the bus and pointed to one of the units above the seats. The unit was vis­i­bly glow­ing through a trans­par­ent cover. “All the air passes through both lamps from an over­head duct. Any air that’s exposed to the light will be ster­il­ized, and any pathogens will be killed,” he said. “The over­all design is fairly sim­ple, but it does what it needs to do.”

“Our design has a cou­ple of unique fea­tures,” Spinella said. “We used reflec­tive alu­minum to line the inside of the ducts, which dou­bles the inten­sity of the UV lamps. We also used an air-flow sen­sor so that when the bus is run­ning and air is flow­ing nor­mally, we can be sure the lamps are on. When the air isn’t mov­ing, the lamps turn off for power efficiency.”

Tests on the FluProof-equipped bus included both UV inten­sity analy­sis and micro­bial air sam­pling. “When we cul­tured the air sam­ples gath­ered from our bus, we dis­cov­ered zero bac­te­r­ial colonies,” Spinella said. “That was even less than what you would see in out­side air, and much less than in a bus with­out our sys­tem installed.”

Team mem­bers have filed for a patent on FluProof and hope to com­mer­cial­ize it. In the mean­time, METRO will keep tabs on their progress.

“When the oppor­tu­nity arose to part­ner with Rice University and the stu­dents, we said, ‘We’re on board,’” said Andrew Skabowski, senior vice pres­i­dent of ser­vice deliv­ery for Houston METRO. “We’ve been a facil­i­ta­tor, more than any­thing. All the engi­neer­ing work was done by the stu­dents, and they were excel­lent. They worked very hard.

“We want to do any­thing we can do to improve the envi­ron­ment within a bus for our pas­sen­gers,” he said. “Cost and reli­a­bil­ity are impor­tant fac­tors to us, but we’ll take a seri­ous look at what­ever they come up with.”

After local media reported on the CityBusters project last fall, the Houston Department of Health and Human Services took issue with the find­ing that bus routes are a risk fac­tor for tuber­cu­lo­sis trans­mis­sion, as detailed in the HTI study, and issued this state­ment: “Tuberculosis trans­mis­sion has never been asso­ci­ated with pub­lic trans­porta­tion. … Transmission of TB is most com­mon among fam­ily mem­bers and other close asso­ciates; casual, irreg­u­lar con­tact in a hall­way or a bus is very unlikely to cause infec­tion.” The state­ment noted UV light from sun­light is an effec­tive dis­in­fec­tant on buses dur­ing day­light hours, and that typ­i­cal pub­lic trans­porta­tion has good mechan­i­cal ven­ti­la­tion and fre­quent door openings.

Despite their reser­va­tions, city offi­cials also value the work Rice stu­dents are doing.

“The Houston Department of Health and Human Services always appre­ci­ates the con­tri­bu­tions of the aca­d­e­mic com­mu­nity in pre­vent­ing the trans­mis­sion of com­mu­ni­ca­ble dis­ease,” said Kathy Barton, chief of pub­lic affairs for the depart­ment. “The CityBusters ini­tia­tive is wor­thy of fur­ther inves­ti­ga­tion, par­tic­u­larly for buses used in longer com­muter routes that may have less air exchange due to fewer stops and may have more darkly tinted win­dows, which reduce the ambi­ent ultra­vi­o­let light. Until sick peo­ple can be con­vinced to stay home, there will always be a need for inno­v­a­tive interventions.”

Source: Rice University release