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10 of 35 are twice as likely to litter as people ages 3549 and littered. The researchers suggested that the threats of shame three times more likely to litter than people over the age of and embarrassment significantly reduce the reported incli- 50. Much of the research conducted during the past 30 years nation to litter. supports those conclusions. Torgler et al. (2008) investigated the relationship between Beck (2007b) assembled and compared eight litter atti- environmental participation and littering in Europe, and tude studies that were completed between 1968 and 2006. demonstrated that membership in an environmental orga- All of the studies were conducted between 1997 and 2006, nization increases the probability of stating that littering is except for the KAB survey conducted in 1968. The follow- never justifiable. The researchers suggest that it may be pos- ing trends and patterns can be noted in the review: sible that encouraging individuals to become active in envi- ronmental organizations could prevent littering. Litter is considered a problem by the majority of respondents in all of the studies conducted since 1997. This may be an indication that litter awareness cam- EVALUATIONS OF STRATEGIES AND MEASURES FOR LITTER PREVENTION paigns have been effective in increasing the percentage of people who believe litter is a problem from 36% in 1968 to 57% and to 87% in the latter studies. Huffman and colleagues (1995) group litter prevention strat- The majority of studies support the notion that young egies into two categories: people are more prone to litter. Five studies indicated that males litter more than Antecedent (preventative) strategies: external stimuli females, two studies reported no difference in the pro- that prompt people to dispose of waste items in a desir- pensity to litter by gender, and one study did not report able way, including prompts, written signs and verbal these data. appeals, community involvement and modeling and The percentage of respondents who personally litter is environmental design. between 43% and 52%. This statistic must be used with Consequence strategies: the rewards of desirable dis- caution because many of the attitude surveys focused posal behaviors or the negative penalties of littering. on the 18- to 45-year-old age cohort, and in four of the studies it was concluded that admissions to littering In a review of 40 articles and 59 studies concerning litter decreased with age. reduction strategies, Huffman and colleagues concluded that The propensity to report someone who litters and the both types of strategies are generally effective in reducing belief that enforcement would stop littering are increas- litter. The consequence strategies generally outperformed ing with time. the preventative strategies. A study by Grasmick et al. (1991) examined a relationship Environmental Conditions between a sense of threat and the likelihood to litter. They hypothesized that There is a well-developed school of thought that the extent of littering in an area or society is largely based on perceived threats of shame and embarrassment function in much the same manner as the threat of legal sanctions in generating social norms. For example, people are more likely to litter compliance with the law. Shame, a self-imposed sanction, in areas that are already littered than in areas that are gener- and embarrassment, a socially imposed sanction, increase ally litter free (Finnie 1973; Krauss et al. 1978; Reiter and the subjective cost of the illegal behavior [littering] and, Samuel 1980). This is because a littered environment reflects thus, reduce the likelihood that the behavior [littering] will occur (p. 234). a social norm that littering is tolerated, whereas a clean envi- ronment reflects a society that is intolerant of littering. In this same research, Grasmick and colleagues (1991) Messaging surveyed independent samples of Oklahoma residents before and 2 years after the introduction of a litter preven- Reiter and Samuel (1980) compared the effect of two types tion campaign. The campaign stressed threats of shame and of litter prevention signs (threatening versus cooperation) on embarrassment for littering and included an AAH program the littering behavior of users of a public parking lot in Sac- and a Don't Lay That Trash on Oklahoma program. The lat- ramento, California. They hypothesized that the presence of ter program emphasized the moral obligations to keep the the sign would reduce the litter rate and that signs with a state clean. The researchers found that a higher proportion cooperative message would be more effective in reducing of respondents in the post-campaign group would not litter litter than signs bearing a threatening message. The threat- in the future, and said that they would feel guilty littering. ening message was "Littering Is Unlawful and Subject to a Also, a higher proportion of respondents in the post-cam- $10 Fine"; the cooperative sign showed a man placing trash paign group believed that they would not be respected if they into a receptacle, with the caption "Pitch In." The research-

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11 ers found that both signs produced lower litter rates relative and the campaign has reduced the amount of visible litter to a no-sign condition. However, the cooperative sign was no on Texas highways by 72% in 6 years (Texas Department of more effective than the threatening sign. Transportation 2008). The DOT asserts that the success is the result of, at least in part, the use of athletes and musicians The results of the present report are consistent with stud- who are admired by the target audience. ies that have shown that polite formulations appealing for help can be effective in reducing littering behavior (Geller et There is no universally accepted pictogram or symbol for al. 1976; Reich and Robertson 1979; Durdan et al. 1985). litter prevention, but the "tidyman" symbol (see Figure 2) is used globally to remind people and entities to be thoughtful In a study concerning the effects of a newspaper media in disposing of their solid waste. The pictogram was first campaign on litter reduction, Schnelle and colleagues (1980) used by Budweiser in the 1950s to encourage people not to conducted an experiment in a small town in Tennessee. The litter. The tidyman pictogram is used by many companies on newspaper campaign consisted of a one-page feature article their product packaging, and has been adopted by Pitch-In appealing to citizens to clean up the town, followed by daily Canada and Keep Britain Tidy as their primary logos. The updates on progress. The researchers found that newspaper use of this symbol is not limited to one country, transcends advertising produced immediate reductions in the amount language barriers, and therefore makes it a good candidate of measured litter. One month subsequent to the cessation for inclusion in litter prevention materials. Also, it is a posi- of the advertising, however, measured litter approximated tive message depicting the act of proper trash disposal, as preexperimental conditions. opposed to a negative message (e.g., "don't litter), which some research suggests is more effective. Also with respect to messaging, Durdan and colleagues (1985) evaluated the effectiveness of various written lit- Indeed, the Manual on Uniform Traffic Control Devices ter prevention prompts in a university cafeteria setting and (FHWA 2003) uses a similar symbol for the Litter Recep- found that: tacle sign (see Figure 3a). The Ontario Traffic Manual (Min- istry of Transportation 2000) proposes a different symbol to Prompting resulted in a significant decrease in litter. advise motorists against littering (see Figure 3b). Positively worded prompts ("please be helpful") were more effective than negatively worded prompts Roadside Advertising ("please don't litter"). Specificity of the prompt had no reliable effect on lit- Roadside advertising is intended to educate drivers that lit- tering behaviors (e.g., "Clear your own table" versus tering is illegal, act as a deterrent to littering, and prompt "Place your tray and dishes in the tray holders along witnesses to report litterers to the appropriate authorities. the west hall"). Roadside signs also remind motorists that the commu- nity is addressing litter, and it promotes a sense of social The researchers also observed that the convenience of responsibility. disposal facilities contributed to a decrease in littering. The Victoria Litter Action Alliance (VLAA) in Australia Cialdini (2003) examined the effectiveness of environ- in conjunction with VicRoads and Victoria Environmental mental protection messaging in the context of the social Protection Agency developed a series of approved roadside norms presented. The researcher describes two kinds of litter prevention signs designed for permanent placement social norms: injunctive norms that outline behaviors that on roads with a speed limit up to 110 kilometers per hour are socially acceptable, and descriptive norms that outline (Victoria Litter Action Alliance 2006). Focus group testing behaviors that are typically performed. Cialdini posits that undertaken to develop the messages for roadside signs found messaging is most effective when the injunctive and social that the most effective signs: norms presented are complementary and not contradictory. For example, a television commercial showing an individual Appear in a series where the message is built upon by being fined for littering (the injunction norm) would be more each sign viewed (signs could be repeated or varied in effective if the scene showed a clean environment rather than the series; a sign appearing once only on a stretch of an already littered environment (the descriptive norm). Field road was more likely to be missed). experiments conducted as part of the research supports the Are used sparingly to avoid visual pollution and dilut- hypothesis. ing the impact. Include signs that address littering and illegal dumping The Texas DOT's Don't Mess With Texas campaign is a separately, as research shows that people differentiate comprehensive litter campaign that employs several social between the acts of littering and illegal dumping. marketing methods and techniques. It is generally regarded Include a phone number, such as a toll-free number, to as a best practices model for DOT litter prevention efforts, act as a deterrent against littering.

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12 (a ) (b ) FIGURE 2 International Tidyman Pictograms: (a ) Traditional symbol; (b ) Modern variation. (a ) (b ) FIGURE 3 Official traffic control devices concerning litter: (a ) Litter receptacle sign; (b ) No littering sign. [Sources: (a ) FHWA 2003; (b ) Ministry of Transportation 2000]. Have the clarity of an immediate and short message, a the good results not solely to the roadside advertising, but phone number, and applicable logos. also to the integration of multiple measures that engage the target audience in different ways. Dowling (2005) reported on the effectiveness of a short- term community roadside litter campaign in Australia, Trash Receptacles which included the following: a publicized launch of the campaign, mobile billboards installed for 3 weeks, six per- Research indicates that in some settings disposal-facility manent roadside signs, a litter-reporting hotline promoted by availability contributes to more use of the facility and less means of radio, newspaper advertisements, brochures, and litter (Finnie 1973; Baltes and Hayward 1976; O'Neill et al. distribution of free car litterbags. The campaign produced an 1980; Mielke 1985; Takahashi 1996). Finnie (1973) is the average litter reduction of about 65%. The authors attribute most relevant to the roadside litter problem, as part of this

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13 experiment involved placing litter receptacles along high- value, which makes it less likely to be discarded, and pro- ways and city streets. Placing litter receptacles along the motes the collection of discarded containers by private inter- highway reduced litter an average of 28.6% and was effec- ests (who wish to redeem collected containers for the cash). tive for at least 6 miles along the highway. Curiously, when Both actions result in a reduction of containers in the litter signs preceded the litter receptacles, the average reduction stream. The success of CDL is a contested issue in litter pre- was only 25.2% compared with a 32% reduction when signs vention. While proponents tout the litter reduction effects, were not present. opponents are quick to posit that CDL is not cost effective and addresses only a portion of the litter stream. The most recent effort in this regard comes from the IAR, which evaluated the effectiveness of receptacles in reduc- The effects of CDL on litter reduction in seven states are ing litter and found that receptacles average a 40% reduction shown in Table 3. Beverage container litter reductions have in litter in both urban and rural settings. Nonetheless, litter consistently been between 70% and 84%, and total litter has receptacles do not by themselves prevent litter, as about 50% been reduced between 34% and 47%. An ancillary positive of littering occurs within 26 feet of a receptacle (Victoria impact of CDL was discovered by Baker et al. (1986) who Litter Action Alliance n.d.). studied the effect of CDL in Massachusetts on the incidence of lacerations in urban children. Records of emergency room Some studies have even investigated the impact of spe- visits for lacerations and fractures were reviewed before and cially designed waste receptacles (e.g., Geller et al. 1980; immediately after implementation of CDL. A case-control O'Neill et al. 1980). The research of O'Neill and colleagues study of children 18 years of age or younger who presented (1980) compared the effects on littering of a conventional to the Emergency Service of Children's Hospital, Boston, for waste receptacle and a specially designed receptacle, and the treatment of lacerations was undertaken. The incidence found that the experimental receptacles collected signifi- of total sutured lacerations did not change substantially cantly more waste than the conventional receptacles. The after the legislation; however, glass-related lacerations fell researchers concluded that the specially designed container by 60% as a result of the reduced incidence in lacerations most likely draws people's attention to desirable waste dis- occurring outside of the home. posal. The O'Neill et al. research was conducted in an Amer- ican football stadium, and the results may not be transferable Ireland implemented a plastic bag levy to reduce the inci- to other locations. dence of plastic bags in the litter stream. It is estimated that plastic bags formed 5% of litter in the Republic of Ireland In more recent research, de Kort et al. (2008) examined before the tax, and according to the national litter pollution the effects of trash can design on littering behavior. The monitoring system, the proportion of plastic bag litter had researchers understood that social and personal norms have fallen to 0.22% by August 2004 (a 95.6% reduction) (Keep the ability to affect behavior, but they contend that these Wales Tidy 2006). Taxes on plastic bags are also in effect in norms are effective only if they are a focus at the correct Belgium, Denmark, Italy, Switzerland, and Taiwan (China). time. Therefore, experimental trash cans were designed to In North America, the province of Quebec is considering a activate a social or personal norm, which was expected to tax on plastic bags (CBC 2007). guide individuals toward antilittering behavior. Two experi- mental trash cans were tested: (1) a typical trash can supple- Table 3 mented with a sign conspicuously placed over the can with EFFECTS OF CONTAINER DEPOSIT LEGISLATION an antilittering message (an explicit message); and (2) a typi- ON LITTER REDUCTION cal trash can with a mirror mounted over the can (an implicit Beverage Container Total Litter message). (Individuals who see their reflection in a mir- State Litter Reduction Reduction ror experience increased self-awareness, including greater New York 70%80% 30% attention to personal norms.) The field study indicated that both trash can designs effectively activated personal norms Oregon 83% 47% and reduced litter by about 50%. Vermont 76% 35% Deposits on High Litter Items Maine 69%77% 34%64% Michigan 84% 41% Container deposit legislation (CDL), also known as a "bot- tle bill," is a law that requires sellers of plastic bottles and Iowa 76% 39% beverage containers to charge a refundable deposit on drink Massachusetts N/A 30%35% containers, such as aluminum cans and plastic bottles. This Source: Container Recycling Institute (2007). results in an empty beverage container retaining some cash Note: N/A = not available.

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14 Adopt-a-Highway Programs Keep America Beautiful Communities The results from the studies in Florida provide evidence The results for 272 combined small and large county sam- of the strong connection between volunteer-adopted road ples showed that KAB sites are 8.5% cleaner than non-KAB programs and reductions in litter (Florida Center for Solid sites (IAR 2006). When split into freeway/rural and urban and Hazardous Waste Management 1997). In 1995, the lit- street categories, the urban KAB sites had a 10.3% lower ter density for large litter items on adopted sites was 36% rate, compared with the freeway/rural sites, which were less than on nonadopted sites, and the adopted sites had 33% 7.4% lower. Similarly, Beck (2007b) reviewed six visible lit- fewer items per site than nonadopted sites. In 1996, the litter ter surveys conducted since 1990 that provided the data to density for large litter items was 20% less on adopted sites measure the litter rates in KAB versus non-KAB communi- than on nonadopted sites, and adopted sites had 19% fewer ties. The results are shown in Table 5 and indicate that KAB items per site than nonadopted sites. The data for 1997 did communities have a 12% lower visible litter rate per mile not show a statistically significant difference between the than non-KAB communities. amount of litter on adopted and nonadopted sites. Table 5 Consecutive state litter surveys from New Jersey indicate EFFECT OF KEEP AMERICA BEAUTIFUL SITES that AAH is an effective litter reduction strategy (Stein and ON LITTER RATES Syrek 2005). AAH sites were 9% cleaner than non-AAH sites from February through April, and 15% cleaner than Visible Litter per Mile non-AAH sites during June and July, when pickup activities KAB vs. Percent are more prevalent. State Year non-KAB Difference Louisiana 1990 No data provided 24% lower A more comprehensive analysis by KAB (Beck 2007b) examined data from seven visible litter surveys. They deter- Kentucky 1998 1,413 vs. 1,707 17% lower mined that AAH programs are effective at reducing lit- Pennsylvania 1999 2,751 vs. 1,980 39% higher ter rates (see Table 4) by about 13%. Only the Mississippi AAH program was ineffective in reducing the prevalence Mississippi 2000 1,800 vs. 2,100 14% lower of roadside litter; if this result is considered an outlier and is North Carolina 2001 950 vs. 1,450 35% lower removed from the data set, AAH programs provide an aver- age reduction of 31% of visible litter items. Tennessee 2006 1,124 vs. 1,389 19% lower Average 12% lower Table 4 Source: Modified from KAB (2007). EFFECT OF ADOPT-A-HIGHWAY PROGRAMS Note: KAB = Keep America Beautiful. ON LITTER RATES Visible Litter per Mile In a 2006 survey in Victoria, Australia, 83% of respon- AAH vs. Percent dents had evaluated their litter management programs, up State Year non-AAH Difference from around 70% in the 2004 survey. However, the majority Hawaii 1993 No data provided 54% lower of respondents undertook the evaluation themselves using observations, litter counts, and face-to-face surveys. Analy- Pennsylvania 1999 1,582 vs. 2,969 47% lower sis of the methods used showed a strong reliance on informal Mississippi 2000 3,600 vs. 1,900 89% higher rather than formal methods. An increased emphasis on the evaluation of programs and initiatives could provide valu- North Carolina 2001 1,250 vs. 1,350 7% lower able input into future policy, program, and regulatory devel- New Jersey 2004 1,532 vs. 1,756 13% lower opments (Victoria Litter Action Alliance 2006). Georgia 2006 1,074 vs. 1,236 13% lower Roadside Mowing Tennessee 2006 311 vs. 610 49% lower Roadside mowing has been investigated as a factor in visible Average 13% lower litter rates (Florida Center for Solid and Hazardous Waste Source: Modified from KAB (2007). Management 1997; Beck 2007a, b). The Florida Litter Sur- Note: AAH = Adopt-a-Highway. vey found that, as grass height increased, the amount of large

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15 litter (litter that was 4 square inches or larger) increased and found on Tennessee roadsides, where 43 mowed sites and the amount of small litter decreased (Florida Center for Solid 52 nonmowed sites were compared (Beck 2007c). The aver- and Hazardous Waste Management 1997). For large litter, age number of items per mile for the mowed sites was 1,513, the litter density at sites with a grass height of 3 to 6 inches whereas the average number of items per mile for the non- was 22% higher than the litter density at sites with a grass mowed sites was 1,400. The researchers assumed that the height of less than 3 inches. Furthermore, long grass had mowed sites were possibly cleaned before mowing, and this 21% more large litter items per site than short grass. The lit- yielded the comparable litter rates. ter density and total number of items per site for small litter items are shown in Table 6. These results are not surprising There is a trend in the roadside maintenance industry, because roadside mowing typically involves maintenance particularly in the southern states, to move toward xeri- workers collecting large items before mowing (to avoid scaping--landscaping in ways that do not require supple- damage to the mowing equipment), or requires mowing over mental irrigation and promote water conservation. In some large items and shredding them into several smaller items. instances, xeriscaping involves the use of nontraditional roadside plantings and treatments that may affect the vis- Table 6 ibility of roadside litter or the ability of the roadside to cap- EFFECT OF ROADSIDE MOWING ON LITTER RATES ture and retain litter. This area of roadside litter requires IN FLORIDA further study. Number of Items Grass Height (inches) Litter Density per Site Incentives <3 167 158 Burgess et al. (1971) evaluated the effectiveness of six dif- 3 to 6 134 128 ferent antilitter procedures on children in neighborhood theaters. The procedures included providing litterbags, pro- >6 100 100 viding litterbags with instructions to use them, providing Source: Data from Florida Center for Solid and Hazardous Waste extra trash cans, showing a special antilitter film before the Management (1997). feature attraction, and providing incentives for the appropri- Note: The results are dimensionless, because they have been ate deposit of litter. The incentive resulted in the removal of normalized. more than 90% of all litter and far outperformed the other five procedures investigated. The transferability of incen- The Georgia Visible Litter Survey (Beck 2007a) con- tives as a measure to reduce roadside litter is uncertain. firmed the Florida results. In Georgia, mowed areas were found to be more than twice as littered than nonmowed Overall, there is a dearth of information concerning areas (when measuring items per mile). However, roadside the impacts of legislation and enforcement on littering and mowing was not considered a factor in the amount of litter litter rates.