Indoor heat exposure in Baltimore: does outdoor temperature matter?

Heat exposure of a population is often estimated by applying temperatures from outdoor monitoring stations. However, this can lead to exposure misclassification if residents do not live close to the monitoring station and temperature varies over small spatial scales due to land use/built environment variability, or if residents generally spend more time indoors than outdoors. Here, we compare summertime temperatures measured inside 145 homes in low-income households in Baltimore city with temperatures from the National Weather Service weather station in Baltimore. There is a large variation in indoor temperatures, with daily-mean indoor temperatures varying from 10 °C lower to 10 °C higher than outdoor temperatures. Furthermore, there is only a weak association between the indoor and outdoor temperatures across all houses, indicating that the outdoor temperature is not a good predictor of the indoor temperature for the residences sampled. It is shown that much of the variation is due to differences in the availability of air conditioning (AC). Houses with central AC are generally cooler than outdoors (median difference of - 3.4 °C) while those with no AC are generally warmer (median difference of 1.4 °C). For the collection of houses with central or room AC, there is essentially no relationship between indoor and outdoor temperatures, but for the subset of houses with no AC, there is a weak relationship (correlation coefficient of 0.36). The results presented here suggest future epidemiological studies of indoor exposure to heat would benefit from information on the availability of AC within the population.

A functional macrophage migration inhibitory factor promoter polymorphism is associated with reduced diffusing capacity

Cigarette smoke exposure is the leading modifiable risk factor for chronic obstructive pulmonary disease (COPD); however, the clinical and pathologic consequences of chronic cigarette smoke exposure are variable among smokers. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine implicated in the pathogenesis of COPD. Within the promoter of the MIF gene is a functional polymorphism that regulates MIF expression (-794 CATT_5-8 microsatellite repeat) ( rs5844572 ). The role of this polymorphim in mediating disease susceptibility to COPD-related traits remains unknown. We performed a cross-sectional analysis of DNA samples from 641 subjects to analyze MIF-794 CATT_5-8 ( rs5844572 ) polymorphism by standard methods. We generated multivariable logistic regression models to determine the risk of low expressing MIF alleles for airflow obstruction [defined by forced expiratory volume in 1 s (FEV₁)/forced vital capacity ratio <0.70] and an abnormal diffusion capacity [defined by a diffusion capacity for carbon monoxide (DL_CO) percent predicted <80%]. We then used generalized linear models to determine the association of MIF genotypes with FEV₁ percent predicted and DL_CO percent predicted. The MIF-794 CATT₅ allele was associated with an abnormal diffusion capacity in two cohorts [odds ratio (OR): 9.31, 95% confidence interval (CI): 1.97-4.06; and OR: 2.21, 95% CI: 1.03-4.75]. Similarly, the MIF-794 CATT₅ allele was associated with a reduced DL_CO percentage predicted in these two cohorts: 63.5 vs. 70.0 ( P = 0.0023) and 60.1 vs. 65.4 ( P = 0.059). This study suggests an association between a common genetic polymorphism of an endogenous innate immune gene, MIF, with reduced DL_CO, an important measurement of COPD severity.

School environmental conditions and links to academic performance and absenteeism in urban, mid-Atlantic public schools

School facility conditions, environment, and perceptions of safety and learning have been investigated for their impact on child development. However, it is important to consider how the environment separately influences academic performance and attendance after controlling for school and community factors. Using results from the Maryland School Assessment, we considered outcomes of school-level proficiency in reading and math plus attendance and chronic absences, defined as missing 20 or more days, for grades 3-5 and 6-8 at 158 urban schools. Characteristics of the environment included school facility conditions, density of nearby roads, and an index industrial air pollution. Perceptions of school safety, learning, and institutional environment were acquired from a School Climate Survey. Also considered were neighborhood factors at the community statistical area, including demographics, crime, and poverty based on school location. Poisson regression adjusted for over-dispersion was used to model academic achievement and multiple linear models were used for attendance. Each 10-unit change in facility condition index, denoting worse quality buildings, was associated with a decrease in reading (1.0% (95% CI: 0.1-1.9%) and math scores (0.21% (95% CI: 0.20-0.40), while chronic absences increased by 0.75% (95% CI: 0.30-1.39). Each log increase the EPA's Risk Screening Environmental Indicator (RSEI) value for industrial hazards, resulted in a marginally significant trend of increasing absenteeism (p < 0.06), but no association was observed with academic achievement. All results were robust to school-level measures of racial composition, free and reduced meals eligibility, and community poverty and crime. These findings provide empirical evidence for the importance of the community and school environment, including building conditions and neighborhood toxic substance risk, on academic achievement and attendance.

Domestic exposure to endotoxin and respiratory morbidity in former smokers with COPD

Indoor air pollution has been linked to adverse chronic obstructive pulmonary disease (COPD) health, but specific causative agents have not yet been identified. We evaluated the role of indoor endotoxin exposure upon respiratory health in former smokers with COPD. Eighty-four adults with moderate to severe COPD were followed longitudinally and indoor air and dust samples collected at baseline, 3 and 6 months. Respiratory outcomes were repeatedly assessed at each time point. The associations between endotoxin exposure in air and settled dust and health outcomes were explored using generalizing estimating equations in multivariate models accounting for confounders. Dust endotoxin concentrations in the main living area were highest in spring and lowest in fall, while airborne endotoxins remained steady across seasons. Airborne and dust endotoxin concentrations were weakly correlated with one another (rs  = +0.24, P = 0.005). Endotoxin concentrations were not significantly associated with respiratory symptoms, rescue medication use, quality of life, or severe exacerbations. In vitro whole-blood assays of the pro-inflammatory capacity of PM10 filters with and without endotoxin depletion demonstrated that the endotoxin component of indoor air pollution was not the primary trigger for interleukin-1β release. Our findings support that endotoxin is not the major driver in the adverse effects of indoor PM upon COPD morbidity.

Home interventions are effective at decreasing indoor nitrogen dioxide concentrations

Nitrogen dioxide (NO2 ), a by-product of combustion produced by indoor gas appliances such as cooking stoves, is associated with respiratory symptoms in those with obstructive airways disease. We conducted a three-armed randomized trial to evaluate the efficacy of interventions aimed at reducing indoor NO2 concentrations in homes with unvented gas stoves: (i) replacement of existing gas stove with electric stove; (ii) installation of ventilation hood over existing gas stove; and (iii) placement of air purifiers with high-efficiency particulate air (HEPA) and carbon filters. Home inspection and NO2 monitoring were conducted at 1 week pre-intervention and at 1 week and 3 months post-intervention. Stove replacement resulted in a 51% and 42% decrease in median NO2 concentration at 3 months of follow-up in the kitchen and bedroom, respectively (P = 0.01, P = 0.01); air purifier placement resulted in an immediate decrease in median NO2 concentration in the kitchen (27%, P < 0.01) and bedroom (22%, P = 0.02), but at 3 months, a significant reduction was seen only in the kitchen (20%, P = 0.05). NO2 concentrations in the kitchen and bedroom did not significantly change following ventilation hood installation. Replacing unvented gas stoves with electric stoves or placement of air purifiers with HEPA and carbon filters can decrease indoor NO2 concentrations in urban homes.

PRACTICAL IMPLICATIONS

Several combustion sources unique to the residential indoor environment, including gas stoves, produce nitrogen dioxide (NO2), and higher NO2 concentrations, are associated with worse respiratory morbidity in people with obstructive lung disease. A handful of studies have modified the indoor environment by replacing unvented gas heaters; this study, to our knowledge, is the first randomized study to target unvented gas stoves. The results of this study show that simple home interventions, including replacement of an unvented gas stove with an electric stove or placement of HEPA air purifiers with carbon filters, can significantly decrease indoor NO2 concentrations.

Predictors of airborne endotoxin concentrations in inner city homes

Few studies have assessed in home factors which contribute to airborne endotoxin concentrations. In 85 inner city Baltimore homes, we found no significant correlation between settled dust and airborne endotoxin concentrations. Certain household activities and characteristics, including frequency of dusting, air conditioner use and type of flooring, explained 36-42% of the variability of airborne concentrations. Measurements of both airborne and settled dust endotoxin concentrations may be needed to fully characterize domestic exposure in epidemiologic investigations.

The effect of copper tripeptide and tretinoin on growth factor production in a serum-free fibroblast model

OBJECTIVE

To evaluate the effect of copper tripeptide and tretinoin on normal and keloid-producing dermal fibroblasts in a serum-free in vitro model. The cellular response was described in terms of viability and secretion of basic fibroblast growth factor (bFGF) and transforming growth factor-beta1 (TGF-beta1).

METHODS

Primary cell lines were established from patient facial skin samples obtained during surgery and plated in serum-free media. At 0 hour, copper tripeptide (1 x 10 (-9) mol/L), tretinoin (1 x 10 (-5) mol/L), or appropriate control vehicle was added. Cell counts and viability were established at 24, 72, and 120 hours. Supernatants were collected at the same intervals and were assessed for bFGF and TGF-beta1 concentrations using the enzyme-linked immunosorbent assay technique.

RESULTS

Cell lines showed viability between 86% and 96% (mean, 92%) throughout the experiment. Tretinoin-treated normal fibroblasts secreted more bFGF than did controls at 24 hours (P<.05). Tretinoin-treated keloid-producing fibroblasts secreted more TGF-beta1 than did controls at 120 hours (P<.05). Keloid-producing fibroblasts treated with copper tripeptide secreted less TGF-beta1 than did controls at 24 hours (P<.05); a similar trend was observed in normal fibroblasts.

CONCLUSIONS

Normal fibroblasts treated with tretinoin produced more bFGF than did controls, and this might partially explain the clinically observed tightening effects of tretinoin. Normal and keloid-producing dermal fibroblasts treated with copper tripeptide secreted less TGF-beta1 than did controls, suggesting a possible clinical use for decreasing excessive scar formation.