Understanding Participation in New York City's Recycling Program


Marjorie J. Clarke, Ph.D.

Geography Department

Hunter College

c/o 1795 Riverside Drive, #5F

New York, NY  10034



Ben Mancell

Geography Department

Hunter College

695 Park Avenue, HN 10th

New York, NY  10021



The Twentieth International Conference
on Solid Waste Technology and Management

April 3 - 6, 2005
Philadelphia, PA U.S.A.


Abstract:  New York City’s recycling program has undergone numerous changes in recent years, and with this, major fluctuations in recycling diversion rate.  Participation in the program also varies considerably from neighborhood to neighborhood.  In 2004 the City released a 20-year Solid Waste Management Plan that proposed a goal of 70% diversion by 2015, but at that time diversion was only 16%, haven fallen from 20% as a result of the four changes that had occurred in the City’s recycling program between July, 2002 and April, 2004. 


Why is there a gap between actual and desired diversion rates and how can it be closed?  Surveys are useful in assessing attitudes towards recycling, and evaluating the type and degree to which barriers exist which prevent or dissuade residents from participating in the recycling program.  Prior research established that certain demographics are highly correlated with diversion rate (i.e., income, educational level, race/ethnic, and female headed households).  This paper postulates some other reasons for the disparity between recycling and non-recycling neighborhoods in recycling participation using thousands of surveys collected by students in parts of the City that have the highest and lowest participation in the recycling program.  Among the variables evaluated are understanding of the recycling program, recycling convenience, attractiveness of building’s recycling environment, reasons for not recycling more, nearby street cleanliness, and home ownership.


Keywords:  recycling, New York City, participation, behavior, attitudes, barriers, enforcement


Background of NYC's recycling program

New York City’s recycling program began in 1988 with pilot programs deployed in different parts of the City at different times collecting different recyclables.  In 1993 the City unified its program, collecting metals, glass, plastic jugs and bottles, newspaper, magazines and corrugated cardboard citywide.  In 1996 mixed paper, bulk metal, grey cardboard, and waxed paper cartons were added.  In 1998 the City Council passed a local law to require weekly collection.[1]  By June, 2002, the Citywide curbside and containerized total diversion rate for recyclables was 19.0% of the entire waste stream, and its capture rate of targeted recyclables averaged 44.2%. [2] (The City targeted almost half the waste stream at that time, based on a 1990 waste composition study.[3])  The low capture rate means that over 55% of the recyclables was thrown out with the trash.


But in July, 2002 the City’s recycling program began to regress.  The City stopped collecting plastics and glass, then a year later reinstated plastics and changed collection frequency to every other week, and then restored glass and weekly collections in April, 2004.  Immediately after plastic and glass stopped being collected, data showed that paper collections had also gone down by 12.7% (from June to September 2002) [4].  When the City changed the program from weekly to once every two weeks, this angered some residents and building superintendents, who were now forced to store recyclables for an additional week.  Meanwhile, in many parts of the City, garbage collections continued at three times per week, with twice a week in the rest of the City.


Since April, 2004, when glass was restored to the recycling program and recyclables were again collected weekly, the diversion rate has been close to 16 to 17% most of the time (January, 2005 figures show 16.2% for citywide curbside and containerized total diversion)[5] or 85% of the recycling rate of June, 2002.  Perhaps the lost diversion is, in part, due to those disaffected by the City’s lack of commitment to recycling or simply confusion about what to recycle or when.


In October, 2004 the Department of Sanitation (DOS) released its latest draft Comprehensive Solid Waste Management Plan, to cover a 20-year time frame.  Goals of 25% diversion of residential recyclables through curbside collection by 2007 and 70% recycling diversion rate for the City’s combined residential and commercial waste stream by 2015 were proposed.  Also stated were goals for a stable, 20-year, curbside program for collecting recyclable paper and metals, glass and plastics, as well as a greater awareness of, and participation in, recycling efforts. [6]


Educational Programs to Inform Recycling

Early in the history of the recycling program, DOS began issuing educational materials to residents primarily via mailed brochures, once every few years on average.  A few cable TV and radio spots, billboards and subway ads were also done, intermittently and a school-based recycling curriculum was issued.    New York City has special challenges with a population including speakers from hundreds of nationalities, with 25 major languages spoken and many more minor ones.  Incomes vary with 20% of residents living below the poverty level, with a majority (60%) with incomes between $15,000 and $75,000.  Only about 9% of homes are single-family detached and over 30% are apartment buildings with 50 or more units.[7]  Communicating knowledge of what to recycle and imparting motivation is clearly important to achieving high diversion rates.  Since 1988, DOS has issued recycling information in both English and Spanish.  DOS placed ads in Spanish papers, as it is required by local law (19 of 1989) to reach every person in the city with recycling education.  At its heyday in the late 1990s, prior to cuts in recycling service started in July, 2002, recycling information was distributed in many languages, including Hebrew, Yiddish, Chinese, Korean, Russian, Polish as well as Spanish in an attempt to get to the populations in which these languages are exclusively spoken.  Pictures of recyclable and non-recyclable materials were featured to increase understanding.  Educational materials were sent to every part of the city including apartments.  However, the City spends on average 81 cents per person annually on recycling education vs. over $3 in San Francisco, which has a 50% diversion rate.[8]


Enforcement Programs to Motivate Recycling

Since the beginning of its recycling programs, DOS has followed a 2-prong strategy to get New Yorkers to recycle:  education and enforcement.   The City considered that people would recycle if they knew what was expected of them and if there was threat of a fine for not recycling.  However, as with many such programs in New York, the enforcement program has been administered unevenly.  At first, the City would not fine anyone for putting recyclables in black bags with garbage.  Initially there were reports of fines to single-family homes fines for not recycling at all or putting garbage with recyclables, but not the converse.   In apartment buildings, fines were issued mainly for not having the correct signage.   In the late 1990s the city began to fine for recyclables in black bags, but only rarely and only in single-family dwellings.  Comparatively little enforcement attention was given to apartments other than pertaining to signage.  Recycling regulations were not specific on the quantity of recycling containers or frequency of emptying them. 


Specifically, as regards sufficient recycling capacity in buildings the codes state that the recycling storage area must be maintained and designated recyclables stored so as not to create a nuisance or sanitary problem.  Also, the building owner must provide a sufficient number of bins in each storage area to prevent containers from spilling over.  16 RCNY §1-08(f) (2)  Fine $25.  Repeat recycling violations are $50 for the 2nd violation, $100 for the third, and $500 for the fourth within a six-month period.  Buildings with ten or more apartments that receive four or more violations within a six-month period can be fined $500 for each bag that violates recycling requirements, up to a maximum of 20 bags within a 24-hour period.  This translates to a maximum fine of $10,000 per day. [9]  While this sounds impressive, the Sanitation department has not enforced but a tiny fraction of the possible violations for buildings not recycling, for putting garbage in recycling bags, and vice versa, lack of signage, unsanitary conditions in the recycling area, or insufficient recycling containers.  Clearly, if 55% of recyclables are in the trash, and if every building placing recyclables in garbage bags were fined for every such bag, it wouldn’t take long before many buildings would either be paying $10,000 per day or enacting procedures within their buildings to improve correct collection of recyclables. 


NYC DOS Research  - Recycling Rates in different NYC neighborhoods

If the people in all NYC did understand what to recycle, one might logically expect for all neighborhoods to have similar, high recycling (diversion) rates.    But there is very large disparity in recycling rates across the city, from below 10% to above 30% [10].  Of the total 59 community board / sanitation districts, the 12 districts with the lowest diversion rates are in the South and Central Bronx (7 districts), Harlem (2 districts), and minority communities in Brooklyn.  On the other end of the spectrum, the 12 districts with the highest diversion rates are in midtown and downtown Manhattan, Brooklyn’s Park Slope, upscale – much like the upper west side of Manhattan, posh residential areas of outer Queens, and eastern Bronx.  Earlier research showed that there is strong correlation (r > .8 at extremely low p) between low educational level, low income, black/Hispanic, and female-headed households with poor diversion rates. [11]


Theory of Behavior; Search for Causes

It would be very convenient to say that there is a causal relationship between the certain demographics and recycling behavior and that these are the only factors influencing recycling behavior.  But behavioral psychologists have shown that there is much more influencing whether or not a behavior, such as recycling, is practiced than simple demographics.  Attitudes, beliefs, social norms, economic factors, and convenience factors towards recycling can override information provided by DOS [12]. 


DOS’ 1999 market research[13] told them that “knowledge about what is recyclable, and the Recycling Program’s rules, is strong.  Residents consider themselves well informed about recycling and correctly identify the major recyclables at very high rates (most over 90%)”.  But DOS recognizes that “self-assessed compliance rates do not match the measured diversion rate of 20% and capture of 50% for NYC.” [14]   Confusion exists about what not to recycle.  One survey of Chinese residents showed that over half of respondents rated the NYC recycling program as good or very good, and another third called it fair.  The main reason for negative ratings (42%) cited “there is still a lot of trash everywhere”.  Conversely, a survey of Hispanic residents indicated that the expanded recycling program as of 1999 vs. prior to the 1996 expansion) is better because it helps keep neighborhoods clean (67%) vs. the general population (21%).  Low-diversion neighborhoods (defined as recycling at less than 12%) also rated the recycling program positively because it helps create a clean neighborhood environment (36%) vs. the general population (25%).  However, low-diversion neighborhoods were also found to mis-identify materials as recyclable when they were not, and had a slightly less enthusiastic view of the program (27%) vs. 33% for the general population. 

In the aforementioned DOS study, low-diversion districts’ residents’ views on compliance and enforcement were overall the same as the general population with the majority believing that recycling should be better enforced and low numbers of people thinking that “if I did not recycle, no one would really know”. [15]


The questions are, why is there so much difference in capture and diversion between the best and worst districts in New York City, and how can the low-diversion districts be brought up to the same level of capture and diversion rates as the best performing districts?  This would involve doubling the capture rate and tripling the diversion rate of the lowest performing districts.   Barriers to recycling could be one answer.  Such barriers can include differences in building design that makes it more difficult to recycle (e.g., tenants must bring recyclables downstairs, outside, or further away in a housing complex vs. leaving recyclables in a recycling / chute room on their floor), or uncooperative building management / superintendent that provides insufficient space / cleanliness of recycling area that is poorly labeled.   But cultural norms and educational levels could be other important factors influencing how a community responds to changes in government programs, illustrating that recycling behavior depends to a great degree on attitudes towards the program.


Capture rates (the percentage of targeted recyclables captured by the recycling program) in the DOS Residential Recycling Diversion Report for June 2003 [16]  were 21 to 35%  in June 2002 but dropped to 15 to 21% in June 2003 in the worst 12 recycling districts.  This drop was probably due to the decision to stop collecting plastic, glass, and waxed paper containers in July 2002).  There was also a drop of 10-12% in paper diversion rate even though paper recycling was unaffected by the change in policy.  The best 12 recycling districts also suffered a drop in capture rates after plastic and glass recycling was dropped, but not to the degree suffered in the low-diversion districts (2002: 39-59%; 2003: 49-68%).  As with recycling (diversion) rate, there is an enormous disparity between the best and worst neighborhoods in the capture rate.  Program changes could have introduced confusion, difficulty in recycling, or irritation at the changing rules, disrupting established routines, perhaps for a long time.  


So, what are the reasons for the large disparity in recycling in New York City neighborhoods?  Is it strictly cultural, involving social norms and beliefs about one’s personal responsibility to recycle?  Or is recycling participation affected by the ability and opportunity to participate, barriers, and experiences with recycling?  If the latter, there are policy decisions that could be made to remove barriers and improve participation.


The CUNY study

Over two thousand New Yorkers, most from the best and worst recycling districts were surveyed by about 50 students from Lehman and Hunter Colleges of the City University of New York in Fall, 2003 and Spring, 2004.  The two-page survey queried respondents about the location of and conditions in their recycling area, the cleanliness of their neighborhood as evidenced by the condition of corner baskets and litter, time it took to get to recycling and garbage areas, home ownership, their knowledge of the recycling program, why they don’t recycle, and demographics.


Data Gathering

Surveys were administered in three time frames:  Fall, 2003, late Winter 2004, and Spring, 2004.  These were administered on the streets of New York City, primarily in the Bronx, Brooklyn, and Manhattan in districts where the diversion rate was high (above 24% or so) or low (below 15% or so).  The students selected one community board district in the list of the best and another in the list of the worst recycling areas, to survey 25-30 passersby randomly in each area, to avoid statistical bias, and to tabulate and compare the results.  In most cases the students had the respondents fill out the survey on a clipboard.  In a few cases where it would ease data collection (they thought due to limitations of literacy) the student read the questions and answers to the person and wrote down their selections.  


Diversion rates are reported by DOS for each of the 59 Sanitation districts on a monthly basis, so for surveys administered in the Fall, 2003 time period, diversion rates for October, November and December were averaged for each district.  Surveys administered in the first three months of 2004 were assigned diversion rates averaging January, February and March rates for each district, and survey data collected from April through June, assigned diversion rates were averaged for those months.  During this nine-month period, diversion rates ranged from 5.3% to 30% in different parts of the City.  Part of the huge range was due to a program change in April, 2004, where glass was added back to the recycling program and recycling pickups were restored to weekly from biweekly, but even prior to 2002 the range in diversion was under 10 to over 30%.


Study Results

The number of 2-page surveys that was verified and completed was 2352 over the three time frames.  Some respondents did not answer all questions, so the following data may be from slightly smaller sample sizes. 


Table 1.  Tabulations of responses from all respondents, all time frames, all locations


The recycling area is not reasonably clean


There are not enough recycling bins


The bins are not emptied often enough


Don’t feel comfortable going to the recycling area


Recycling area is not located conveniently on the way out of the building


Did not know:


            Plastic bottles are recycled


            Plastic bags are not recycled


            Metal objects are recycled


            Phone books are recycled 


Had wrong answer for recycling status of Glass bottles at the time of survey


      Pre-April wrong answer for glass bottles = 58.8%.

      Post-April wrong answer for glass bottles = 16.9%


Main reason for not recycling all recyclable items every time:


   I forget to recycle


   I don’t think I should have to recycle 


   It is difficult for me to get to the recycling area


   The recycling area is unpleasant


   I’m confused about what to recycle


   I don’t have time to go to the recycling area


See overflowing litter baskets in immediate neighborhood every day or frequently


See a lot of litter on the streets or sidewalks in neighborhood every day or frequently



Breaking down the datasets into categories of similar diversion rate it is possible to characterize variables a little more meaningfully:


Answered 100% Correct of what is recyclable in NYC’s program (five questions):


where avg diversion rate is 5.6%


where avg diversion rate is 30%


But these results contradict DOS’ finding that “Majorities correctly identify the major recyclables, most at very high rates (over 90%).   High knowledgeability is seen regardless of where residents live, what type of housing they reside in, or whether English or Spanish is their primary language”.[17] 


A lot of litter is seen frequently or every day in the neighborhood


in lowest diversion rate districts  (5.6% diversion)


in highest diversion rate districts (30% diversion)



In order to perform correlations on data where there is a yes/no answer on a survey, the data (pre- and post-April, 2004) were first grouped into 29 categories of diversion rate ranging from 5.6% to 30%.   Then these data were transformed such that the percent of those respondents in each diversion category answering affirmatively to a question would be averaged for each question.  For each survey question (variable) there were 29 data points, one representing each diversion category and the average percent answering yes for the question within that diversion category.  A number of variables were correlated with diversion rate using the Pearson Product-Moment Correlation (see Table 2).  A number of moderate to very strong positive or negative relationships were found (see Table 3 for interpretation) [18]  Note that the p values for each are very low, indicating certainty about the results.


Table 2.  Correlations of Factors Reflecting Recycling Behavior vs. High Diversion Rate


Positive Relationships


p value

Recycling Area Clean



Recycling Room on same floor



Almost Never / Rarely See Litter Factor



Almost Never / Rarely See Overflowing Garbage Cans Factor



Enough Recycling Bins



Comfortable Going to Recycling Area



100% Knowledge of 5 Recyclables questions



Recycling Bins Emptied Often enough



Apartment Ownership






Inverse Relationships


p value

Everyday / Frequently See Litter on the Streets Factor



Everyday / Frequently See Overflowing Garbage Cans Factor



Recycling Area is Unpleasant



Don't Want to Recycle



One of the factors strongly correlated (.821) with high diversion rate is cleanliness of the recycling area.  Table 4 shows r values for various factors vs. cleanliness of recycling area. 


Table 3.  Interpretation of Correlation Coefficients


            Size of the Correlation Coefficient                 General Interpretation

                        .8 to 1.0                                               Very strong relationship

                        .6 to .8                                                 Strong relationship

                        .4 to .6                                                 Moderate relationship

                        .2 to .4                                                 Weak relationship

                        .0 to .2                                                 Weak or no relationship



Table 4. Correlations of Factors Reflecting Recycling Behavior vs. Cleanliness of Recycling area

Positive Relationships


p value

Almost Never / Rarely See Overflowing Garbage Cans Factor



Almost Never / Rarely See Litter Factor



Optimal Recycling Conditions Factor



Income Over $45,000



100% Knowledge of Recyclables



Apartment Ownership






Inverse Relationships


p value

Everyday / Frequently See Litter Factor



Everyday / Frequently See Overflowing Garbage Cans Factor



Low Education Factor



African American / Hispanic Factor



Low Income Factor



Unpleasant Recycling Area



Don't Want to Recycle




Another of the factors strongly correlated (.728) with high diversion rate is having a recycling room on the same floor.  Table 5 shows other factors moderately to strongly correlated with having a recycling room on the same floor:


Table 5. Correlations of Factors Reflecting Recycling Behavior vs. Nearby Recycling Room


Pearson’s r

p value

Apartment Ownership



Apartment Buildings With Over 100 Units



Recycling Area Clean



Comfortable Going to Recycling Area



Rarely / Almost Never See Overflowing Garbage Cans in Neighborhood



100% Knowledge of Given Recyclables




The correlations below are only those data after April 1, 2004 when the program resumed collection of glass and weekly collections.



Table 6.  Correlations of Factors Influencing Recycling Behavior vs. High Diversion Rate


Positive Relationships with diversion rate

Pearsons r

p value

Recycling Room on same floor



  Enough Recycling bins in recycling area



  Recycling area reasonably clean



  Know to recycle phone books



Own apartment



Rarely see a lot of litter on neighborhood streets




Negative Relationships with diversion rate

Pearsons r

p value

Frequently see a lot of litter on neighborhood streets



NYC Housing Authority tenant




Aside from the demographic correlations with diversion rate, established with prior research, the above indicates that those who have a recycling room on their floor, have enough bins in a clean recycling area, who own their apartments, and are not Housing Authority tenants, and who don’t often see a lot of litter on the streets, are most apt to live in higher diversion rate districts.  Though many of the factors that are strongly correlated with high diversion rates cannot be changed by City policy (e.g., demographics), some of these factors that directly or indirectly are related to high diversion rate can be affected by City enforcement policy and funding. 


Table 7.  Other positive correlations

                                                                                                                                    r           p

Having a recycling room on same floor and White



Recycling area unpleasant and See overflowing garbage cans on street daily



Recycling area unpleasant and See a lot of litter on streets daily



Getting 100% correct on recycling knowledge questions and White



No Building Recycling area  and NYC Housing authority



Recycling room reasonably clean and White



Not wanting to recycle and living in apt bldg 25-50 units



Frequently see overflowing garbage cans and Hispanic



Having a basement recycling area and Hispanic



Difficult to recycle and Don’t know where recycling area is



Recycling Rooms on the floor  and Recycling area is clean



Recycling Rooms on the floor and There are enough recycling bins



Difficult to recycle and frequently see garbage cans overflowing



Middle School and 20% knowledge questions correct



Recycling Rooms on the floor and Own apartment



Having enough recycling bins and White



Frequently see a lot of litter on streets and Hispanic



Live in NYC Housing Authority and Hispanic



Live in NYC Housing Authority and got 20% knowledge questions correct



Difficult to recycle and frequently see a lot of litter on streets



Forgetting to recycle and being Asian



Live in NYC Housing Authority and got 0%  knowledge questions correct




Table 8.  Other negative correlations

                                                                                                                                    r           p

No Time to recycle and Highest Education: Middle school



Correct answer to Glass bottles recycled and Middle School



Unpleasant and Rarely see a lot of litter on streets



Not wanting to recycle and being Asian



Having a recycling room on same floor and Black



No Building Recycling area  and Correct answer to glass bottle recycling



Forgetting to recycle and Highest Education: Community College



NYC Housing Authority and Feel comfortable going to recycling area



Seeing a lot of litter on streets every day and White



100% correct answers to five knowledge questions and Hispanic



Difficult to recycle and Recycling area located conveniently



Reasonably clean recycling area and Hispanic



Difficult to recycle and White



Unpleasant and Recycling area clean



NYC Housing Authority and Correct answer to Glass bottles recycled



NYC Housing Authority and 100% correct answers to knowledge questions



Enough recycling bins and Hispanic



Rarely see a lot of litter on streets and Black



Difficult to recycle and Enough Recycling Bins



Difficult to recycle and Own apartment



Forgetting to recycle and Not Wanting to Recycle




Conclusions and Recommendations

DOS has taken a first step in improving, or at least stabilizing, recycling participation by recommending in its solid waste management plan that the recycling program be kept stable, since capricious changes and reversals confuse and anger many residents and building supers.  Further it has recommended ongoing research into the attitudes and reasons for non-recycling behavior.                                                                    


The above research suggests that diversion rates are related not only to cultural issues, but also to the existence of barriers to recycling (unclean / unsavory conditions in the recycling area and the neighborhood in general).    Diversion rates might be increased via identification and reduction of any barriers to recycling via better enforcement of existing laws (e.g., require building managers to provide sufficient bins and servicing for them in well-lit, safe, clean, rodent-free areas, conveniently located) and tailoring educational signage to different types of building layout. 


It doesn’t seem to matter whether a person lives in a high or low-diversion rate district; people are confused about the recycling program and forget to recycle.  This means that ongoing citywide campaigns to remind people to recycle and to clarify the aspects of the recycling program are both needed.  Increasing the frequency of outreach and differentiating the type of educational approach (i.e. use not only printed literature, but other ways of reaching these target populations with greater frequency than heretofore), is clearly necessary to penetrate and convince those non-recyclers to get with the program.  The students’ survey experiences in the poor recycling neighborhoods suggest that DOS should not assume that everyone has an equal understanding and motivation to recycle.  The recycling program would be more effective if it were made even simpler than it has for those residents with very low educational experience and if the educational devices were tailored to take advantage of differences in cultural values.


Street corner basket collections and street sweeping appear to have a relationship with recycling rates.  These findings would suggest that the City’s recycling program would benefit by increasing street cleaning and litter basket servicing in poor diversion areas.  Improving the frequency and quality of street sweeping, better enforcement of sidewalk cleaning rules, and more frequent litter basket service, may increase neighborhood pride and inspire more personal responsibility for recycling, improving attitudes about recycling in the low-diversion neighborhoods of New York City. 



[1] “Local Law 59 of 1998”, New York City Council.

[2] Cipollina, Larry, “Residential Recycling Diversion Report for June 2002”, NYC Department of Sanitation memo, September 27, 2002.

[3] “A Comprehensive Solid Waste Management Plan for New York City and Final Generic Environmental Impact Statement”, Appendix Volume 1.1 Waste Stream data, NYC Department of Sanitation, August 1992.  and  “New York City Waste Composition Study 1989-1990 (four volumes)”, NYC Department of Sanitation.

[4] Cipollina, Larry “Residential Recycling Diversion Report for September 2002”, December 5, 2002 and “Residential Recycling Diversion Report for June 2002”, September 27, 2002.

[5] Cipollina, Lorenzo N., “Preliminary January Curbside Recycling”, Department of Sanitation memo, Feb. 17, 2005.

[6] “Draft Comprehensive Solid Waste Management Plan”, NYC Department of Sanitation, October, 2004, p. ES-13.s.  http://www.ci.nyc.ny.us/html/dos/pdf/pubnrpts/swmp-4oct/ex-summary.pdf

[7] “Recycling: What do New Yorker’s Think?  Five Years of Market Research”, NYC Department of Sanitation, http://www.ci.nyc.ny.us/html/dos/pdf/pubnrpts/recyrpts/recy_mktg.pdf   p. 18.

[8]Processing and Marketing Recyclables in New York City: Rethinking Economic, Historical, and Comparative Assumptions”, NYC DOS.  http://www.ci.nyc.ny.us/html/dos/html/recywprpts.html#3  May 2004

[9] New York City Department of Sanitation Digest of Sanitation Codes, condensed from the New York City Health and Administrative Code. p. 25-29.  September. 2004.  http://www.ci.nyc.ny.us/html/dos/pdf/digest/digest.pdf

[10] New York City Recycling – In Context – A Comprehensive Analysis of Recycling in Major U.S. Cities. Appendix III, NYC Department of Sanitation, August, 2001  http://www.ci.nyc.ny.us/html/dos/html/recywprpts.html

[11] Clarke, Marjorie J., “Optimizing Recycling in All the Neighborhoods of New York City:  The Roles of Demographics, Education, Barriers, and Program Changes”, Nineteenth Annual International Conference on Solid Waste Technology and Management, Philadelphia, PA, March 21 – 24, 2004.

[12] Clarke, Marjorie J. , Testing the Effectiveness of Supermarket-Based Environmental Shopping Campaigns in Changing Consumer Behavior in New York City, Doctoral Dissertation, City University of New York, New York, NY.  September, 1999.

[13] “Recycling: What do New Yorker’s Think?  Five Years of Market Research”, NYC Department of Sanitation, Fall, 1999. p. 16, 68-70.  http://www.ci.nyc.ny.us/html/dos/pdf/pubnrpts/recyrpts/recy_mktg.pdf

[14]New York City Recycling – In Context – A Comprehensive Analysis of Recycling in Major U.S. Cities”, NYC DOS, August, 2001, P. 41

[15] “Recycling: What do New Yorker’s Think?  Five Years of Market Research”, NYC Department of Sanitation, Fall, 1999. p. 65.  http://www.ci.nyc.ny.us/html/dos/pdf/pubnrpts/recyrpts/recy_mktg.pdf

[16] “Residential Recycling Diversion Report for June 2003”, from Larry Cipollina, September 8, 2003.

[17]New York City Recycling – In Context – A Comprehensive Analysis of Recycling in Major U.S. Cities”, NYC DOS, August, 2001, P. 41  http://www.nyc.gov/html/dos/html/recywprpts.html#1

[18] Salkind, Neil J. (2004). Statistics For People Who (Think They) Hate Statistics, Second Edition, p. 88. California: Sage Publications, Inc.