Saving Da Vinci's Last Supper from air pollution

In late 2009, the refectory of Santa Maria Delle Grazie Church, where the painting is located, installed a sophisticated heating, ventilation, and air conditioning system to protect the painting from the polluted air of Milan.

To test the effectiveness of their pollution countermeasures, Italian officials called on Constantinos Sioutas, Fred Champion professor of civil and environmental engineering at the USC Viterbi School of Engineering. For his ongoing research, Sioutas has designed unobtrusive air samplers that are compact and quiet.

"These air pollution sampling technologies are ideally suited for use in sensitive facilities such as art galleries and museums. They do not disrupt the day-to-day operations of the facility," Sioutas said.

A multi-national team that includes USC scientists used the monitors to determine that indoor pollution has been drastically reduced at the church, though visitors enjoying the painting remain a potential source of soiling. The team's findings will be presented in December in Milan.

The team deployed two sets of air quality monitors for one year at the church, and found that – for the most part – the Italian authority responsible for the facility housing the famous painting (Soprintendenza per i Beni Architettonici e per il Paesaggio di Milano) is winning the war with outdoor air pollution. Fine and coarse particulate matter concentrations were reduced around the painting by 88 and 94 percent, respectively from their corresponding outdoor levels.

"It's a spectacular reduction," Sioutas said. "It is, frankly, very impressive."

Indoor sources of pollution, however, may still pose a threat of soiling on the Last Supper. Nancy Daher, USC graduate student and lead author of a journal article on the team's findings, said that fatty lipids from the skin of visitors to the church still appeared in significant quantities around the painting – even with visitor access to the painting strictly regulated. Her article appears this month in Environmental Science and Technology.

Only a handful of patrons are allowed into the church via an airlock-style chamber at any given time, and are only allowed to stay for 15 minutes at a stretch.

Airborne lipids from visitors' skin can combine with dust in the air and, if they come in contact with the painting, soil it, Daher said.

"Even the painting itself is emitting," she said. Tiny particles of wax used in early repair efforts on the painting also can get into the air, soiling the painting in the same manner.

In addition to aiding in the conservation of the Last Supper, the team's research can be used as a benchmark for future studies aimed at protecting indoor artworks and antiquities.

Provided by University of Southern California (news : web)

Determining pollution level of a medium without wasting tools, time or solvents possible

 Polycyclic aromatic hydrocarbons (PAH) are organic compounds that can be highly contaminant. They are found, amongst other places, in soils occupied by metallurgical or pharmaceutical industries and in waters polluted by ships' fuel. Chemist Dani Zuazagoitia has proposed simple techniques for analysing the impact of PAHs on a number of media, based on headspace solid phase microextraction (HS-SPME). He drew up the methodology, prepared it for the pertinent circumstances and applied it in the Basque province of Gipuzkoa.

Zuazagoitia defended the thesis at the University of the Basque Country(UPV/EHU), with the title Fase solidoko mikroerauzketan oinarritutako metodoen garapena hidrokarburo aromatiko poliziklikoen determinaziorako. Aplikazioa eta ebaluazioa ingurumen laginetan (Development of SPMEs for determining PAHs. Application and evaluation in environmental samples).

Zuazagoitia has published a number of articles on his research, the latest being in the journal Soil & Sediment Contamination, and entitled "Evaluation of soil contamination by polycyclic aromatic hydrocarbons in Gipuzkoa (Northern Spain)".

Extraction without touching the sample

The HS-SPME procedure for the analysis of samples is a screening method; these analyses provide a rapid response (positive/negative) without wasting tools, time or solvents. With this procedure in concrete, a needle is inserted into the sample container top. This needle contains a fibre that has to be taken out of it on insertion, so that the substance to be analysed is absorbed from the headspace. This space is that between the sample and the cap and information can be obtained from there only in the case of volatile compounds such as PAHs. The procedure of extraction from the headspace enables conserving the fibre in optimum conditions. If it is inserted directly into the sample it can be spoilt due to the large molecules, but using HS-SPME, non-volatile and large molecule interference is avoided.

After extraction desorption should be proceeded with, in order to free the gases absorbed by the fibre and thus separate the substances. Zuazagoitia opted for gas chromatography, by which the components can be separated with notable volatility at temperatures less than 350-400 degrees. Subsequently, the components were quantified using an FIDionisation detector.

Optimisation of three procedures

For his thesis Zuazagoitia developed methods which, based on HS-SPME, determined various small and medium molecular weight PAHs simultaneously, considering the diversity of conditions that these methods have to comply with, depending on the matrix to analyse (water, earth, sediments, and so on). Likewise, given the numerous variables that condition the process, an experimental design that optimised the response of the method was opted for. Using the Statistica® programme, it is not necessary to carry out trials with each variable in order to ascertain their ups and downs beforehand.

Zuazagoitia stated that, effectively, there exist rapid and simple methods and that can be undertaken with any laboratory analytical tools. Other characteristics of these methods involve having a rapid response (positive/negative) objective and being environmentally friendly, on not using organic solvents. The three procedures optimised in the thesis (water, earth, sediments) comply with these features.

In San Sebastián, Bergara and Pasaia

The researcher also took on the task of putting into practice methods for studying the pollution of water, earth and sediments in Gipuzkoa. According to the samples analysed, the concentrations of PAHs in the sea and river water in the territory are not relevant. However, there is a high level of contamination in leached waters, meaning that there is a high concentration of PAHs in soil these originate from. With the soil samples, Zuazagoitia detected high levels of pollution in two zones of San Sebastian (the capital city of Gipuzkoa): in an area where a gas factory used to be located (in Morlans, Amara); and in a store for timber that was treated with creosote, a toxic substance (in Oriamendi). Finally, as regards sediments, PAHs were found in all the locations analysed and especially in the towns of Bergara (river Deba) and Pasaia (river Oiartzun).

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The above story is reprinted (with editorial adaptations ) from materials provided by Elhuyar Fundazioa.

Disease-Causing Compound Found in Air Clogged with Smoke from Cigarettes, Fires or Pollution

Inhaling cigarette smoke or smoggy air is clearly not great for your health. And exposure to various kinds of smoke has been associated with cardiovascular disease, rheumatoid arthritis and cataracts.

Researchers have now pinpointed a compound common in disparate forms of smoke that might explain some of the frequent ills associated with it. The findings are described in a new paper published online May 16 in the Proceedings of the National Academy of Sciences.

"We found isocyanic acid in a number of places, from air in downtown Los Angeles and air downwind of a Colorado wildfire, to cigarette smoke," Jim Roberts, a chemist at NOAA's Earth System Research Laboratory and co-author of the new study, said in a prepared statement. Isocyanic acid—abbreviated as HNCO—is a substance known to act in the body along disease-related pathways through a process known as protein carbamylation.

Although the new study did not look specifically at how ambient HNCO might be affecting people's health, the researchers note that it makes sense that it would have easy access into the human body's innards. "It dissolves readily in water, which means that humans can be exposed directly if it gets into eyes or lungs," Roberts said.

This is the first time that HNCO had been measured in ambient air, the researchers report. To get specific readings, the team used a negative-ion proton-transfer chemical ionization mass spectrometer.

Roberts and his colleagues measured high concentrations of the compound in the air in Boulder, Colo., during last year's Fourmile Canyon fire and in the smoggy city of Los Angeles, finding that both had about 200 parts per billion HNCO. Previous findings have indicated that levels higher than one part per billion in the ambient air might have negative impacts on human health. The high levels in L.A. are likely an unintended consequence of efforts to curb nitrogen emissions from diesel trucks. These so-called urea-selective catalytic reduction systems scrub out nitrogen but create HNCO as a byproduct, the researchers report.

In addition to these significant concerns for people living here in the U.S., the risks might be greater for the many people in the developing world who use open-fire stoves, or cook stoves. A lab test of burning biomass produced concentrations of 600 parts per billion when measured close to the flames. "There are literally billions of people in the world who burn biomass for cooking and heating," Roberts said. "If these indoor fires release similar levels of isocyanic acid as the fires we studied in the laboratories, families could be exposed to high levels of the chemical."

The team underscored the need for further research into how HNCO might be affecting human health—especially with the prevalence of biomass-based stoves and the prediction for more wild fires due to climate change. "We may be facing a future of higher amounts of HNCO in the atmosphere," Roberts said. And although that might be bad news for human health, Roberts noted that at least "it is fortunate that now we can measure it."

Image courtesy of iStockphoto/plherrera

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