Box-Jenkins stochastic models for studying air pollutants in a Latin American megacity

The objective of this paper is to show the development of Box-Jenkins stochastic models to study the behavior of air pollutants concentrations in the megacity of Bogotá, Colombia. Information was collected from 10 stations in the city’s air quality monitoring network over a ten-year period. The temporal relationship between air pollutants, their spatial variation, and the occurrence of extreme pollution episodes was studied using Box-Jenkins models. The results showed that the moving average term of the models developed was the main indicator of spatial distribution for the daily pollutant concentrations. In the case of atmospheric particulate matter < 10 μm, the following spatial distribution was identified in the megacity: northwestern, center-southwest, and southeast. For atmospheric particulate matter < 2.5 μm: north, center, and southwest. For ozone: northwest, center, and south. Maximum hourly particulate matter concentrations were observed between 6-10 a.m., and between 11 a.m. - 4 p.m. for ozone. Monthly, the highest particulate matter concentrations were observed in February (14.1%), January (13.5%), and March (12.2%). In the context of atmospheric physics, this study was relevant for the following findings: The usefulness of Box-Jenkins models in simulating the temporal behavior of air pollutants, and for their adequate performance in detecting urban spatial trends.

Oral bioavailability reveals an overestimation of the toxicity of polycyclic aromatic hydrocarbons in atmospheric particulate matter

Polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulate matter have adverse effects on human health, yet total PAH concentrations should overestimate the toxicity compared to the bioavailable amount of PAHs. To explore this hypothesis, we measured PAHs oral bioavailability in vitro in particulate matter with aerodynamic diameter lower than 10 µm (PM10) using a test that mimics the human digestive system. This assay combines the use of simulated gastrointestinal fluids and a dialysis membrane to simulate intestinal absorption. Results show that oral PAH bioavailability was below 5%, with fluorene, anthracene, acenaphthene and phenanthrene as the most bioavailable PAHs. Data suggest no carcinogenic risk of oral bioavailable PM10-bound PAHs following a health risk assessment via inhalation-ingestion by using benzo(a)pyrene-equivalent carcinogenic concentration and hazard indexes. To our best knowledge, this is the first research study of in vitro oral bioavailability estimation of PM10-associated PAHs.

Particulate Matter and Human Health

This chapter provides an introduction to particulate matter by discussing various ways of categorisation, characterisation and their health effects. The natural and anthropogenic sources of atmospheric particulate matter are discussed. The chapter also introduces qualitatively some aerosol concepts, such as their chemical composition and size distribution. Some examples are provided to illustrate how particulate matter, despite being microscopic particles, can manifest themselves in the atmosphere. Finally, the various pathways by which particulate matter impacts the health system are reviewed along with their interactions to understand concept behind the PM-associated health effects.

Characteristics and Potential Inhalation Exposure Risks of Environmentally Persistent Free Radicals in Atmospheric Particulate Matter and Solid Fuel Combustion Particles in High Lung Cancer Incidence Area, China

Environmentally persistent free radicals (EPFRs) were previously considered an unrecognized composition of air pollutants and might help explain the long-standing medical mystery of why non-smokers develop tobacco-related diseases such as lung cancer. However, there is no investigated on EPFRs in Xuanwei rural areas, especially in high prevalence of lung cancer areas. In this study, we selected six types of coal and three types of biomass in Xuanwei, then conducted simulated combustion, and six group of atmospheric particulate matters (APMs) to explore the content and particle size distribution pattern of EPFRs and a new health risk assessment method to evaluate the risk of EPFRs in PM for adults and children. Our results show that the contribution of EPFRs for biomass combustion, coal combustion and APMs were mainly distributed in the size range of <1.1 μm, which accounted for 76.15 ± 4.14%, 74.85 ± 10.76%, and 75.23 ± 8.18% of PM3.3. The mean g factors and ΔHp-p indicated that the EPFRs were mainly oxygen-centered radicals in PM in Xuanwei. The results suggest that the health risk of EPFRs is significantly increased when the particle size distribution of EPFRs is taken into account, and coal combustion particulate matter (174.70 ± 37.86 cigarettes for an adult, 66.39 ± 14.39 cigarettes per person per year for a child) is more hazardous to humans than biomass combustion particulate matter (69.41 ± 4.83 cigarettes for an adult, 26.37 ± 1.84 cigarettes per person per year for), followed by APMs (102.88 ± 39.99 cigarettes for an adult, 39.10 ±15.20 cigarettes per person per year for) in PM3.3. Our results provides a new perspective and evidence for revealing the reason for the high incidence of lung cancer in Xuanwei, China.

Occurrence of aliphatic and aromatic compounds associated with atmospheric particulate matter in three cities of Gujarat, India

The organic pollutants associated with atmospheric particulate matter (PM) in the environment, especially PM2.5 (particles <2.5 μm) have become a major issue worldwide in the past decade. The ambient air samples of four different sizes of particles were collected using an active air sampler (cascade impactor) from three cities of Gujarat: Anand, Ahmedabad and Surat. To study morphology and elemental composition, Scanning electron microscope (SEM) and Energy dispersive X-ray system (EDX) were used for fine particle size <1.0 μm. Besides, organic pollutants associated with particulate matter were analyzed using Gas Chromatography-Mass Spectrometry (GC–MS). Total 54 organic chemicals including 29 aliphatic (alkanes and alkanoic acids) and 25 aromatic chemical compounds were identified qualitatively. Phthalate, the well-known plasticizer was found in the atmosphere of all three study sites. In addition, polycyclic aromatic hydrocarbons (PAHs) such as naphthalene and fluorene were quantified at high concentrations in Ahmedabad (315 ng/m3 and 509 ng/m3 respectively) followed by Surat (310 ng/m3 and 382 ng/m3) and Anand (76.1 ng/m3 and 123 ng/m3). The distribution of organic chemicals was found diverse at three locations which might be influenced by the different sources and landmass usage in each city. The presence of the carbonaceous elements in the particles indicates biomass burning emissions during the winter season which might be a source of pollutants in the studied areas.