Exposure to traffic-related particle matter and effects on lung function and potential interactions in a cross-sectional analysis of a cohort study in west Sweden

Genetic susceptibility to airway inflammation and exposure to short-term outdoor air pollution

BACKGROUND

Air pollution is a large environmental health hazard whose exposure and health effects are unequally distributed among individuals. This is, at least in part, due to gene-environment interactions, but few studies exist. Thus, the current study aimed to explore genetic susceptibility to airway inflammation from short-term air pollution exposure through mechanisms of gene-environment interaction involving the SFTPA, GST and NOS genes.

METHODS

Five thousand seven hundred two adults were included. The outcome measure was fraction of exhaled nitric oxide (FeNO), at 50 and 270 ml/s. Exposures were ozone (O₃), particulate matter < 10 µm (PM₁₀), and nitrogen dioxide (NO₂) 3, 24, or 120-h prior to FeNO measurement. In the SFTPA, GST and NOS genes, 24 single nucleotide polymorphisms (SNPs) were analyzed for interaction effects. The data were analyzed using quantile regression in both single-and multipollutant models.

RESULTS

Significant interactions between SNPs and air pollution were found for six SNPs (p < 0.05): rs4253527 (SFTPA1) with O₃ and NO_x, rs2266637 (GSTT1) with NO₂, rs4795051 (NOS2) with PM₁₀, NO₂ and NO_x, rs4796017 (NOS2) with PM₁₀, rs2248814 (NOS2) with PM₁₀ and rs7830 (NOS3) with NO₂. The marginal effects on FeNO for three of these SNPs were significant (per increase of 10 µg/m³):rs4253527 (SFTPA1) with O₃ (β: 0.155, 95%CI: 0.013-0.297), rs4795051 (NOS2) with PM₁₀ (β: 0.073, 95%CI: 0.00-0.147 (single pollutant), β: 0.081, 95%CI: 0.004-0.159 (multipollutant)) and NO₂ (β: -0.084, 95%CI: -0.147; -0.020 (3 h), β: -0.188, 95%CI: -0.359; -0.018 (120 h)) and rs4796017 (NOS2) with PM₁₀ (β: 0.396, 95%CI: 0.003-0.790).

CONCLUSIONS

Increased inflammatory response from air pollution exposure was observed among subjects with polymorphisms in SFTPA1, GSTT1, and NOS genes, where O₃ interacted with SFTPA1 and PM10 and NO₂/NO_x with the GSTT1 and NOS genes. This provides a basis for the further exploration of biological mechanisms as well as the identification of individuals susceptible to the effects of outdoor air pollution.

Auto repair workers exposed to PM2.5 particulate matter in Barranquilla, Colombia: telomere length and hematological parameters

Exposure to 2.5 µm particulate matter (PM_2.5) in automotive repair shops is associated with risks to health. We evaluated the effects of occupational exposure to PM_2.5 among auto repair-shop workers. Blood and urine samples were collected from 110 volunteers from Barranquilla, Colombia: 55 active workers and 55 controls. PM_2.5 concentrations were assessed at each of the sampling sites and chemical content was analyzed by SEM-EDS electron microscopy. The biological samples obtained were peripheral blood (hematological profiling, DNA extraction) and urine (malondialdehyde concentration). Telomere length was assessed by qPCR and polymorphisms in the glutathione transferase genes GSTT1 and GSTM1 by PCR-RFLP, with confirmation by allelic exclusion. White blood cell (WBC), lymphocyte (LYM%) and platelet (PLT) counts and the malondialdehyde concentration were higher (4.10 ± 0.93) in the exposed group compared to the control group (1.56 ± 0.96). TL was shorter (5071 ± 891) in the exposed individuals compared to the control group (6271 ± 805). White blood cell (WBC) and platelet counts were positively associated with exposure. Age and TBARS were correlated with TL in exposed individuals. The GSTT1 gene alleles were not in Hardy-Weinberg (H-W) equilibrium. The GSTM1 gene alleles were in H-W equilibrium and allelic exclusion analysis confirmed the presence of heterozygous GSTM1 genotypes. SEM-EDS analysis showed the presence of potentially toxic elements, including Mg, Al, Fe, Mn, Rh, Zn, and Cu. Auto repair shop workers showed effects that may be associated with exposure to mixtures of pollutants present in PM_2.5. The GSTM1 and GSTT1 genes had independent modulatory effects.

Short-term effects of the toxic component of traffic-related air pollution (TRAP) on lung function in healthy adults using a powered air purifying respirator (PAPR)

Short-term exposure to traffic-related air pollution (TRAP) are associated with reduced lung function. However, TRAP is a mixture of various gaseous pollutants and particulate matter (PM), and therefore it is unknown that which components of TRAP are responsible for the respiratory toxicity. Using a powered air-purifying respirator (PAPR), we conducted a randomized, double-blind, crossover trial in which 40 adults were exposed to TRAP for 2 h at the sidewalk of a busy road. During the exposure, the participants wore the PAPR fitted with a PM filter, a PM and volatile organic compounds (VOCs) filter, or a sham filter (no filtration, Sham mode). The participants were blinded to the type of filter in their PAPR, and experienced three exposures, once for each intervention mode in random order. We measured two lung function measures (forced expiratory volume in 1 s [FEV1] and forced vital capacity [FVC]) and an airway inflammation marker (fraction of exhaled nitric oxide [FE_NO]) before and immediately after each exposure, and further measured them at different time periods after exposure. We applied linear mixed effect models to estimate the effects of the interventions on the changes of lung function from baseline values after controlling for other covariates. Compared to baseline, exposing to TRAP decreased FEV1 and FVC, and increased FEV1/FVC and FE_NO in all three intervention modes. The mixed models showed that with the sham mode as reference, lung function and airway inflammation post exposure were significantly improved by filtering both PM and VOCs, but marginally affected by filtering only PM. In conclusion, the VOCs component of TRAP is responsible for the reduction in lung function caused by short-term exposure to TRAP. However, the result needs to be interpreted cautiously before further verified by laboratory experiment using purely isolated component(s) of TRAP.

Air pollution and increased number of psychiatric emergency room visits: A case-crossover study for identifying susceptible groups

BACKGROUND

Ambient particulate matter is a leading risk factor for disease globally. Particulate matter 10 (PM₁₀) and particulate matter 2.5 (PM_2.5) are derived from different sources, including operating motor vehicles as well as from industrial activities. In this study we investigate the association between increased concentrations of PM and total daily visits to the psychiatric emergency unit (PEV). Further, the aim is to identify specific risk groups who are more susceptible to the effects of air pollution exposure by studying sex, age, ongoing psychiatric follow-up and diagnoses of depression/anxiety or substance use.

MATERIAL AND METHODS

The sample was comprised of data from 2740 days to 81 548 PEVs at Sahlgrenska University Hospital in Gothenburg and daily mean concentrations of PM₁₀ and PM_2.5. A time-stratified case-crossover design was used to analyse associations between air pollution and PEVs.

RESULTS

Mean number of daily PEVs were 35 and sex distribution was even. PM exposure was associated with total PEV at lag 0 (the same day), by RR 1.016 (95% confidence interval [CI] 1.004-1.028) and RR 1.020 (95%CI 1.003-1.038) per 10 μg/m³ increase in PM₁₀ and PM_2.5, respectively. In females, PEV were increased at lag 0 and lag 1, and in males at lag 1 and lag 2. In the age-stratified analysis, PEVs significantly increased following PM exposure amongst individuals aged 35-65 years by lag 0-2 and in individuals who had contact with outpatient care at lag 0 to lag 1. There were no associations between air pollution and PEVs for any specific diagnostic group evaluated (amongst depression, anxiety and substance use disorder).

CONCLUSIONS

The results indicate that acute exposure to PM₁₀ and PM_2.5 may trigger acute worsening in mental health in both males and females, especially among 35-65 year old individuals. However, in subgroups of the most common psychiatric diagnoses, we did not observe statistically significant associations with PM exposure.

Epigenetic regulation is involved in traffic-related PM2.5 aggravating allergic airway inflammation in rats

Increasing fine particulate matter (PM_2.5) and epigenetic modifications are closely associated with the pathogenesis of asthma, but the definite mechanism remains unclear. The traffic-related PM_2.5 exposure aggravated pulmonary inflammation and changed the methylation level of interferon gamma (Ifng) and interleukin (Il)4 genes, and then altered levels of affiliated cytokines of IFN-γ and IL-4 in rats with allergic airway inflammation. It also increased the level of miR146a and decreased the level of miR31. In addition, transcription factors of nuclear factor kappa B (NF-κB) and signal transducer and activator of transcription 6 (Stat6) rose; forkhead box P3 (Foxp3) and signal transducer and activator of transcription 4 (Stat4) lowered. The traffic-related PM_2.5 altered epigenetic modifications in allergic airway inflammation of rats leading to inflammation exacerbation through impaired regulatory T (Treg) cells function and T-helper type 1 (Th1)/Th2 cells imbalance, which provided a new target for the treatment and control of asthma.

Respiratory symptoms, lung function, and fraction of exhaled nitric oxide before and after assignment in a desert environment-a cohort study

BACKGROUND

Inhalation of small particulate matter (PM 2.5) may be associated with development of respiratory disease. Increased respiratory symptoms have been reported among military staff after service in countries with recurrent desert storms.

OBJECTIVE

The aim was to investigate whether an assignment in a desert environment and exposure to desert storms are associated with negative effects on respiratory health.

METHODS

In two cohorts of Swedish soldiers serving in Mali as part of the United Nations stabilization forces, examination with spirometry, determination of fraction of exhaled nitric oxide (FeNO), and a questionnaire including participant characteristics, symptoms, and exposure was performed before and after service. Ambient air sampling was conducted on-site. Paired t-test was used to compare pre- and post-variables on lung function data, FeNO and symptom level.

RESULTS

Most indoor and outdoor air measurements of dust and silica were within the Swedish occupational exposure limit for PM2.5 and silica (<0.10-2.7 mg/m³ and <0.002-0.40 mg/m³, respectively) as well as for respirable dust and silica (0.056-0.078 mg/m³and 0.0033-0.025 mg/m³, respectively). In the subgroup of participants with reported exposure to desert storms during the stay in Mali, forced expiratory volume in 1 s (FEV₁) was significantly lower after exposure than before the mission (mean litres (SD) 4.21 ± 0.66 vs 4.33 ± 0.72, p = 0.021).

CONCLUSION

Exposure to a desert storm was associated with a decrease in FEV₁. Exposure to small particulate matter may contribute to the development of respiratory disease and thus spirometry should be performed after occupational exposure to desert storms.

Personal exposure levels to O3, NOx and PM10 and the association to ambient levels in two Swedish cities

Exposure to air pollution is of great concern for public health although studies on the associations between exposure estimates and personal exposure are limited and somewhat inconsistent. The aim of this study was to quantify the associations between personal nitrogen oxides (NO_x), ozone (O₃) and particulate matter (PM₁₀) exposure levels and ambient levels, and the impact of climate and time spent outdoors in two cities in Sweden. Subjects (n = 65) from two Swedish cities participated in the study. The study protocol included personal exposure measurements at three occasions, or waves. Personal exposure measurements were performed for NO_x and O₃ for 24 h and PM₁₀ for 24 h, and the participants kept an activity diary. Stationary monitoring stations provided hourly data of NO_x, O₃ and PM, as well as data on air temperature and relative humidity. Data were analysed using mixed linear models with the subject-id as a random effect and stationary exposure and covariates as fixed effects. Personal exposure levels of NO_x, O₃ and PM₁₀ were significantly associated with levels measured at air pollution monitoring stations. The associations persisted after adjusting for temperature, relative humidity, city and wave, but the modelled estimates were slightly attenuated from 2.4% (95% CI 1.8-2.9) to 2.0% (0.97-2.94%) for NO_x, from 3.7% (95% CI 3.1-4.4) to 2.1% (95% CI 1.1-2.9%) for O₃ and from 2.6% (95% 0.9-4.2%) to 1.3% (95% CI - 1.5-4.0) for PM₁₀. After adding covariates, the degree of explanation offered by the model (coefficient of determination, or R²) did not change for NO_x (0.64 to 0.63) but increased from 0.46 to 0.63 for O₃, and from 0.38 to 0.43 for PM₁₀. Personal exposure to NO_x, O₃ and PM has moderate to good association with levels measured at urban background sites. The results indicate that stationary measurements are valid as measure of exposure in environmental health risk assessments, especially if they can be refined using activity diaries and meteorological data. Approximately 50-70% of the variation of the personal exposure was explained by the stationary measurement, implying occurrence of misclassification in studies using more crude exposure metrics, potentially leading to underestimates of the effects of exposure to ambient air pollution.