Inflammatory markers and lung function in relation to indoor and ambient air pollution

Determinants of Indoor NO2 and PM2.5 Concentration in Senior Housing with Gas Stoves

Nitrogen dioxide (NO2) and particulate matter of 2.5 microns (PM2.5) are air pollutants that impact health, especially among vulnerable populations with respiratory disease. This study identifies factors influencing indoor NO2 and PM2.5 in low-income households of older adults with asthma who use gas stoves in Lowell, Massachusetts. Environmental sampling was conducted in 73 homes, measuring NO2, PM2.5, fractional stove-use, temperature, and humidity for 5-7 days. Participants were recruited between December 2020 and July 2022. Questionnaires were used to collect data on factors influencing indoor NO2 and PM2.5 concentrations. Daily outdoor NO2 and PM2.5 concentrations were obtained from a United States Environmental Protection Agency (EPA) monitoring station. Paired t-tests were conducted between indoor and outdoor NO2 and PM2.5 concentrations, and linear regression was used to evaluate factors influencing indoor NO2 and PM2.5 concentrations. The average indoor concentration for NO2 and PM2.5 were 21.8 (GSD = 2.1) ppb and 16.2 (GSD = 2.7) µg/m3, respectively. Indoor NO2 and PM2.5 concentrations exceeded outdoor concentrations significantly. In multiple regression models, season and pilot light stove use significantly predicted indoor NO2. Season and air freshener use for 6-7 days/week significantly predicted indoor PM2.5. Season-influenced higher indoor concentrations are likely due to reduced ventilation in colder months in the Northeast U.S.

Ambient air pollution, low-grade inflammation, and lung function: Evidences from the UK Biobank

The associations of ambient air pollution exposure and low-grade inflammation with lung function remain uncertain. In this study, 276,289 subjects were enrolled in the UK Biobank. Individual exposure to ambient air pollution (including nitrogen dioxide [NO2], nitrogen oxides [NOx]), and particulate matter [PM2.5, PM10, PMcoarse]) were estimated by using the land-use regression model. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were tested, and low-grade inflammation score (INFLA score) was calculated for each subject. In this cross-sectional study, the median concentrations of air pollution were 9.89 µg/m3 for PM2.5, 15.98 µg/m3 for PM10, 6.09 µg/m3 for PMcoarse, 25.60 µg/m3 for NO2, and 41.46 µg/m3 for NOx, respectively. We observed that PM2.5, PM10, PMcoarse, NO2, NOx was negatively associated with lung function. Besides, significant positive associations between PM exposure and low-grade inflammation were noted. Per interquartile range (IQR) increase in PM2.5, PM10, and PMcoarse was related to higher INFLA score, and the β (95 % CI) was 0.06 (0.03, 0.08), 0.03 (0.02, 0.05), and 0.03 (0.01, 0.04), respectively. Additionally, we found significant negative associations between INFLA scores and lung function. One-unit increase in INFLA score was linked with 12.41- and 11.31-ml decreases in FVC and FEV1, respectively. Compared with individuals with low air pollution exposure and low INFLA scores, participants with high air pollution and high INFLA scores had the lowest FVC and FEV1. Additionally, we observed that INFLA scores could modify the relationships of PM2.5, NO2, and NOx with FVC and FEV1 (Pinteraction <0.05). The negative impact of air pollutants on lung function was more pronounced in subjects with high INFLA scores in comparison to those with low INFLA scores. In conclusion, we demonstrated negative associations between ambient air pollution and lung function, and the observed associations were strengthened and modified by low-grade inflammation.

Indoor air pollution and airway health

Because of the disproportionate amount of time that people spend indoors and the complexities of air pollutant exposures found there, indoor air pollution is a growing concern for airway health. Both infiltration of outdoor air pollution into the indoor space and indoor sources (such as smoke from tobacco products, cooking or heating practices and combustion of associated fuels, and household materials) contribute to unique exposure mixtures. Although there is substantial literature on the chemistry of indoor air pollution, research focused on health effects is only beginning to emerge and remains an important area of need to protect public health. We provide a review of emerging literature spanning the past 3 years and relating indoor air exposures to airway health, with a specific focus on the impact of either individual pollutant exposures or common combustion sources on the lower airways. Factors defining susceptibility and/or vulnerability are reviewed with consideration for priority populations and modifiable risk factors that may be targeted to advance health equity.

Causal effects of air pollutants on lung function and chronic respiratory diseases: a Mendelian randomization study

Objectives

Our study aims to clarify the causality between air pollutants and lung function, chronic respiratory diseases, and the potential mediating effects of inflammatory proteins.

Method

We employed Mendelian Randomization (MR) analysis with comprehensive instrumental variables screening criteria to investigate the effects of air pollutants on lung function and chronic lung diseases. Our study incorporated genetic instruments for air pollutants, ensuring F-statistics above 20.86. A total of 18 MR analyses were conducted using the inverse-variance weighted approach, along with heterogeneity and pleiotropy tests to validate the results. Mediated MR analysis was utilized to evaluate the inflammatory proteins mediating the effects of air pollutants.

Result

MR analysis demonstrated significant causal interactions of particulate matter 2.5 (PM2.5), PM10, and Nitrogen dioxide (NO2) with lung function decline. Specifically, PM10 negatively affected forced expiratory volume in one second (FEV1) (OR: 0.934, 95% CI: 0.904-0.965, p = 4.27 × 10-5), forced vital capacity (FVC) (OR: 0.941, 95% CI: 0.910-0.972, p = 2.86 × 10-4), and FEV1/FVC (OR: 0.965, 95% CI: 0.934-0.998, p = 0.036). PM2.5 and NO2 were identified as potential risk factors for impairing FEV1 (OR: 0.936, 95% CI: 0.879-0.998, p = 0.042) and FEV1/FVC (OR: 0.943, 95% CI: 0.896-0.992, p = 0.024), respectively. For chronic respiratory diseases, PM2.5 and NO2 were associated with increased COPD incidence (OR: 1.273, 95% CI: 1.053-1.541, p = 0.013 for PM2.5; OR: 1.357, 95% CI: 1.165-1.581, p = 8.74 × 10-5 for NO2). Sensitivity analyses confirmed the robustness of these findings, with no significant heterogeneity or horizontal pleiotropy detected.

Conclusion

Our study ascertained the causal correlations of air pollutants with lung function and COPD, emphasizing the importance of reducing air pollution. Interleukin-17A mediates the reduction of FEV1 and FVC by PM10, revealing potential therapeutic targets.

Impact of indoor air pollution on DNA damage and chromosome stability: a systematic review

Indoor air pollution is becoming a rising public health problem and is largely resulting from the burning of solid fuels and heating in households. Burning these fuels produces harmful compounds, such as particulate matter regarded as a major health risk, particularly affecting the onset and exacerbation of respiratory diseases. As exposure to polluted indoor air can cause DNA damage including DNA sd breaks as well as chromosomal damage, in this paper, we aim to provide an overview of the impact of indoor air pollution on DNA damage and genome stability by reviewing the scientific papers that have used the comet, micronucleus, and γ-H2AX assays. These methods are valuable tools in human biomonitoring and for studying the mechanisms of action of various pollutants, and are readily used for the assessment of primary DNA damage and genome instability induced by air pollutants by measuring different aspects of DNA and chromosomal damage. Based on our search, in selected studies (in vitro, animal models, and human biomonitoring), we found generally higher levels of DNA strand breaks and chromosomal damage due to indoor air pollutants compared to matched control or unexposed groups. In summary, our systematic review reveals the importance of the comet, micronucleus, and γ-H2AX assays as sensitive tools for the evaluation of DNA and genome damaging potential of different indoor air pollutants. Additionally, research in this particular direction is warranted since little is still known about the level of indoor air pollution in households or public buildings and its impact on genetic material. Future studies should focus on research investigating the possible impact of indoor air pollutants in complex mixtures on the genome and relate pollutants to possible health outcomes.

Residential exposure to mold, dampness, and indoor air pollution and risk of respiratory tract infections: a study among children ages 11 and 12 in the Danish National Birth Cohort

BACKGROUND

The burden of respiratory tract infections (RTIs) is high in childhood. Several residential exposures may affect relative rates.

OBJECTIVES

To determine risk of RTIs in children ages 11 and 12 by residential exposures.

METHODS

We included children in the Danish National Birth Cohort (DNBC) at ages 11 and 12. We estimated incidence risk ratios (IRR) and 95% confidence intervals (CI) for counts of RTIs within the last year by exposure to mold/dampness, gas stove usage, summer and winter candle-burning, fireplace usage, cats and dogs indoors, and farmhouse living. We also estimated IRR and 95% CI for RTIs for predicted scores of four extracted factors ('owned house', 'mold and dampness', 'candles', and 'density') from exploratory factor analyses (EFA).

RESULTS

We included 42 720 children with complete data. Mold/dampness was associated with all RTIs (common cold: IRRadj 1.09[1.07, 1.12]; influenza: IRRadj 1.10 [1.05, 1.15]; tonsillitis: IRRadj 1.19 [1.10, 1.28]; conjunctivitis: IRRadj 1.16 [1.02, 1.32]; and doctor-diagnosed pneumonia: IRRadj 1.05 [0.90, 1.21]), as was the EFA factor 'mold/dampness' for several outcomes. Gas stove usage was associated with conjunctivitis (IRRadj 1.25 [1.05, 1.49]) and with doctor-diagnosed pneumonia (IRRadj 1.14 [0.93, 1.39]). Candle-burning during summer, but not winter, was associated with several RTIs, for tonsillitis in a dose-dependent fashion (increasing weekly frequencies vs. none: [IRRadj 1.06 [0.98, 1.14], IRRadj 1.16 [1.04, 1.30], IRRadj 1.23 [1.06, 1.43], IRRadj 1.29 [1.00, 1.67], and IRRadj 1.41 [1.12, 1.78]).

CONCLUSION

Residential exposures, in particular to mold and dampness and to a lesser degree to indoor combustion sources, are related to the occurrence of RTIs in children.

Joint association of air pollution exposure and inflammation-related proteins in relation to infant lung function

BACKGROUND AND AIM

Systemic inflammation is one potential mechanism underlying negative impact of air pollution on lung function. Levels of inflammation-related proteins have the potential to characterize infants' susceptibility to air pollution induced lung function impairment. This study aimed to examine the interplay between air pollution exposure and inflammation-related proteins on lung function in 6-months-old infants.

METHODS

In the EMIL birth cohort from Stockholm (n = 82), dynamic spirometry, along with measurement of plasma levels of 92 systemic inflammation-related proteins (Olink Proseek Multiplex Inflammation panel) have been carried out in infants aged six months. Time-weighted average exposure to particles with an aerodynamic diameter of <10 μm (PM10), <2.5 μm (PM2.5), and nitrogen dioxide (NO2) at residential addresses from birth and onwards was estimated via validated dispersion models. To characterize the abnormality of inflammation-related protein profile, for each protein in each infant, we calculated the relative deviance of the protein level from age- and sex-specific median in terms of its age- and sex-specific interquartile range (IQR), followed by computing the absolute value of the smallest relative deviance, "minimum absolute deviance". Using linear regression models, interaction of air pollution and the abnormal inflammatory profile on lung function was estimated on the additive scale.

RESULTS

We found joint association of PM exposure and an abnormal inflammatory protein profile in relation to FEV0.5 and FVC. For 0.1 unit increase in minimum absolute deviance, one IQR increase in PM10 was associated with 85.9 ml (95% CI: -122.9, -48.9) additional decrease in FEV0.5, and 72.3 ml (95% CI: -121.5, -23.2) additional decrease in FVC. Similar results were obtained with PM2.5 exposure, while less apparent for NO2.

CONCLUSIONS

Early life air pollution exposure and abnormal inflammation-related protein profiles may interact synergistically towards lower lung function in infants.

Exposure to different residential indoor characteristics during childhood and asthma in adolescence: a latent class analysis of the Danish National Birth Cohort

BACKGROUND

Many residential indoor environments may have an impact on children's respiratory health.

OBJECTIVES

The aims of this study were to identify latent classes of children from the Danish National Birth Cohort (DNBC) who share similar patterns of exposure to indoor home characteristics, and to examine the association between membership in the latent classes and asthma in adolescence.

METHODS

We included data on residential indoor characteristics of offspring from the DNBC whose mothers had responded to the child's 11-year follow-up and who had data on asthma from the 18-year follow-up. Number of classes and associations were estimated using latent class analysis. To account for sample selection, we applied inverse probability weighting.

RESULTS

Our final model included five latent classes. The probability of current asthma at 18 years was highest among individuals in class one with higher clustering on household dampness (9, 95%CI 0.06-0.13). Individuals in class four (with higher clustering on pets ownership and living in a farm) had a lower risk of current asthma at age 18 compared to individuals in class one (with higher clustering on household dampness) (OR 0.53 (95%CI 0.32-0.88), p = .01).

CONCLUSION

Our findings suggest that, in a high-income country such as Denmark, groups of adolescents growing up in homes with mold and moisture during mid-childhood might be at increased risk of current asthma at age 18. Adolescents who grew-up in a farmhouse and who were exposed to pets seem less likely to suffer from asthma by age 18.

Short-Term Effects of Side-Stream Smoke on Nerve Growth Factor and Its Receptors TrKA and p75NTR in a Group of Non-Smokers

Environmental tobacco smoke remains a major risk factor, for both smokers and non-smokers, able to trigger the initiation and/or the progression of several human diseases. Although in recent times governments have acted with the aim of banning or strongly reducing its impact within public places and common spaces, environmental tobacco smoke remains a major pollutant in private places, such as the home environment or cars. Several inflammatory and long-term biomarkers have been analysed and well-described, but the list of mediators modulated during the early phases of inhalation of environmental tobacco smoke needs to be expanded. The aim of this study was to measure the short-term effects after exposure to side-stream smoke on Nerve Growth Factor and its receptors Tropomyosin-related kinase A and neurotrophin p75, molecules already described in health conditions and respiratory diseases. Twenty-one non-smokers were exposed to a home-standardized level of SS as well as to control smoke-free air. Nerve Growth Factor and inflammatory cytokines levels, as well the expression of Tropomyosin-related kinase A and neurotrophin receptor p75, were analysed in white blood cells. The present study demonstrates that during early phases, side-stream smoke exposure induced increases in the percentage of neurotrophin receptor p75-positive white blood cells, in their mean fluorescent intensity, and in gene expression. In addition, we found a positive correlation between the urine cotinine level and the percentage of neurotrophin receptor-positive white blood cells. For the first time, the evidence that short-term exposure to side-stream smoke is able to increase neurotrophin receptor p75 expression confirms the very early involvement of this receptor, not only among active smokers but also among non-smokers exposed to SS. Furthermore, the correlation between cotinine levels in urine and the increase in neurotrophin receptor p75-positive white blood cells could represent a potential novel molecule to be investigated for the detection of SS exposure at early time points.

Use of candles and risk of cardiovascular and respiratory events in a Danish cohort study

Burning candles at home emit small particles and gases that pollute indoor air. Exposure to fine particles in outdoor air has been convincingly linked to cardiovascular and respiratory events, while the associations with fine and ultrafine particles from candle burning remain unexplored. We examined the association between the use of candles and incident cardiovascular and respiratory events. We collected data on 6757 participants of the Copenhagen Aging and Midlife Biobank cohort recruited in 2009 and followed them up for the first hospital contact for incident cardiovascular and respiratory events until 2018. We investigated an association between the self-reported frequency of candle use in wintertime and cardiovascular and respiratory events, using Cox regression models adjusting for potential confounders. During follow-up, 1462 and 834 were admitted for cardiovascular and respiratory events, respectively. We found null associations between candle use and a hospital contact due to cardiovascular and respiratory events, with hazard ratios (HRs) and 95% confidence intervals (CI) of 0.97 (95% CI: 0.84, 1.11) and 0.98 (95% CI: 0.81, 1.18), respectively, among those using candles >4 times/week compared with <1 time/week. For cause-specific cardiovascular diseases, HRs were 1.10 (95% CI: 0.85, 1.43) for ischemic heart disease and 1.18 (95% CI: 0.77, 1.81) for myocardial infarction. For chronic obstructive pulmonary disease, HR was 1.26 (95% CI: 0.81, 1.97). We found no statistically significant associations between candle use and the risk of cardiovascular and respiratory events. Studies with improved exposure assessments are warranted.

Exposure to Aerosols Emitted from Common Heating Combustion Sources Indoors—The Jordanian Case as an Example for Eastern Mediterranean Conditions

In Jordan, ~61% of total residential energy consumption is consumed by heating spaces using portable kerosene (K) and liquified petroleum gas (LPG) heaters. Here, we evaluated the indoor air quality (IAQ) versus the use of K and LPG heaters inside a test room reflecting the typical conditions of Jordanian dwellings during the winter season. The experimental setup included particle size distribution (diameter 0.01–25 µm) measurements, and we utilized a simple sectional indoor aerosol model (SIAM) to estimate the emission rate and lifetime of the combustion products in the test room. The particle number (PN) concentration during the LPG operation was 6 × 104–5.9 × 105 cm−3, depending on the setting at minimum, medium, or maximum. The K heater operation increased with the PN concentrations to a range of 4 × 105–8 × 105 cm−3. On average, the particle losses were 0.7–1.6 h−1 for micron particles (1–10 µm) and 0.8–0.9 h−1 for ultrafine particles (<0.1 µm). The emission rate from the LPG heater was 1.2 × 1010–2.8 × 1010 particles/s (6.6 × 106–8.0 × 106 particles/J), and that for the K heater was about 4.4 × 1010 particles/s (1.9 × 107 particles/J). The results call for the immediate need to apply interventions to improve the IAQ by turning to cleaner heating processes indoors.