Our primary objective was to determine if any relationship existed between neighborhood characteristics and the presence of indoor allergens, since this had not been previously studied. We examined the relationship between various neighborhood-level predictors and the presence of indoor allergens in the household, even after adjusting for building-level housing code violations. Previous studies have explored the relationship between housing conditions and indoor allergens. Concerning dust mite and cat allergen, previous literature has been inconsistent in its reporting of the relationship between housing conditions and the presence of these allergens. Therefore it is difficult to assess whether our results demonstrating an association between neighborhood-level housing code violations and dust mite/cat allergens in multivariate linear models is consistent with previous findings concerning the housing unit level. (103
Previous studies have found a relationship between poor housing conditions and the presence of cockroach allergen (35
) and elevated mouse allergen. (58
) We demonstrated an association between cockroach and mouse allergen, and the prevalence of housing code violations at the neighborhood level even after adjusting for building level housing code violations. Graphically, the relationship between serious housing code violations and the presence of mouse allergen can be seen in , which shows neighborhoods with high levels of housing code violations to overlap neighborhoods with higher levels of mouse allergen. Overall, these relationships suggest that, where many of the leading indoor allergens are concerned, we may need to consider prevention and treatment options at the neighborhood-level. Though more work is needed to determine the relationship between neighborhood factors and the presence of allergens, it seems that reducing serious housing code violations may decrease exposure to allergens, which are related allergic sensitization and asthma.
Housing Code Violations and Mouse Allergen (MUP), Bronx, New York
This study had a few limitations. First, while this was a prospective birth cohort, we only assessed allergen measurements and neighborhood-level characteristics cross-sectionally. Therefore, no causal statements can be made. Furthermore, these analyses were limited to a small baseline cohort sample (N=261) of Puerto Rican participants with a history of mother inhalant allergy or asthma. Therefore, we can not generalize beyond this population. Furthermore, limitations existed in the actual measurement of exposures. Many neighborhood-level exposures were proxy variables, (e.g. mean roadway length), while still other relevant variables were unavailable (e.g. specific types of neighborhood housing code violations). Since one of our major findings was the importance of neighborhood-level housing code violations, it seemed important to adjust for building-level violations to see if this mediated any of the neighborhood level effect. It did not, and in fact, adjusting for building-level violations strengthened the neighborhood effect.
However, it is clear that the neighborhood-level and building-level housing code violations were not drawn in the same way in the New York City data systems we used for this analysis. Furthermore, even though we did not achieve perfect tertiles with the serious housing code violations variable, the amount of violations in the medium and high categories were so egregious that such findings seem plausible given previous literature, and subsequent analyses controlling for building-level house code violations. Lastly, since some participants were missing dust samples, because not enough dust was drawn, results could be biased. Yet allergen levels in this study were comparable to other New York City studies examining indoor allergens. (39
) Compared to other non New York City-specific studies measuring indoor allergens, our levels of cat and dust allergen were generally low, while levels of cockroach and mouse allergen were generally high. The levels in our study are not comparable to national data, since such data are less representative of urban areas with high population density and high density of high-rise buildings. (37
Despite these limitations, this work suggests avenues for additional research. First, future research should further explore the association between neighborhood-level characteristics and the presence of indoor allergens. Currently, neighborhood-level factors are not considered in asthma prevention strategies. For example, the most recent “Guidelines for the Diagnosis and Management of Asthma” from the National Asthma Education and Prevention Program does not discuss neighborhood-level factors. (106
) However, Wright and colleagues have discussed neighborhood factors in terms of asthma prevention. (8
Increasingly, urban planning and public health researchers and practitioners are aware of the need for collaboration between these two fields. (16
) This study suggests some ways in which such collaborations may happen. For example, the New York City Department of City Planning can target “high-risk” community districts (those with high levels of housing code violations, for example). The Department could include a health objective on future building and planning bids, and require future projects to discuss how a new project would solve, prevent, or alleviate health concerns. For example, if a developer is interested in creating a new mixed-use space in the Bronx near the Cross-Bronx Expressway, she would need to explain how the firm is taking measures to mitigate the harmful air and noise pollution byproducts of the expressway that might be experienced by future commercial and residential tenants. In addition, she might explain how the project would prevent dust from spreading into neighboring areas while the project is being constructed, and how the project plans to minimize construction noise. In partnership with the NYC Department of Mental Health and Hygiene, and the Department of City Planning, the City of New York could be a model for consciously combining these issues of the built environment and health into its work practice. The Furman Center has several data indicators at the community district level which can be helpful to projects which consider both built environment and health issues; these indicators include elevated blood lead levels, infant mortality rate, low birth weight rate, severe crowding rate, tax delinquencies, racial diversity index, rental units that are subsidized, and residential units within ¼ mile of a park. (95
Future studies should incorporate a larger city-wide, or nationally, representative sample of U.S. participants to further clarify the relationship between neighborhood characteristics and asthma morbidity and mortality. The focus on Puerto Ricans in this study was important, since the asthma burden is so high in this population, but future studies should aim to clarify the relationship of neighborhood-level issues and asthma morbidity in a representative sample. The use of multilevel modeling will help to isolate neighborhood, building and individual level effects. (115
Such future studies should also further extend the measurement of neighborhood characteristic variables, which was not possible in this study. Though it is certainly positive that the area level data used in this study was publicly available, we need to continue working toward fuller measurement. Future studies might more precisely examine the relationship between neighborhood traffic pollutants (116
), specific types of housing code violations (35
) and asthma morbidity. For example, available data on serious housing code violations may have actually underestimated the relationship with asthma-related allergens since it only pertained to one class of housing violations, and did not include NYC public housing. (120
) Future studies should both collect their own neighborhood-level data, and request more publicly available data from governmental entities, e.g. housing and planning agencies.
The definition of neighborhood is also an important issue for future work. Two important concerns informed the decision to use community planning districts as the spatial unit in our work, although most current thought in spatial epidemiology suggests the use of smaller spatial areas (e.g. census tracts). (121
) First, the sample size was too small to consider spatial areas aside from these districts; it would have been difficult to consider participants’ outcomes and area level issues if so few of them were within each spatial unit. (122
) Second, the NYC Department of City Planning uses these districts to design and implement redevelopment as well as new building and neighborhood projects. Therefore, districts are spatial units with policy and planning relevance, and employing them in public health research may serve as a vehicle to link health issues to indicators regularly maintained by government officials, including information on housing types, parks, vacant land, commercial space, and facilities. (123
City agencies, such as health departments, transportation and planning boards, the police, and housing authority, wield a good deal of power over the health of neighborhood residents. Community district policies regarding incentives for landlords for fewer housing violations and quicker remediation if violations occur might be useful remedies to reduce asthma burden. Likewise, planning boards might instruct architects and developers to explicitly incorporate health objectives into their design plans. A health lens needs could be used to assess the possible health effects of urban polices and programs, for example through the application of a methodology such as Health Impact Assessment.