Ambient Ozone Monitoring Research Articles

Gradient-Based Colorimetric Array Sensor for Continuous Monitoring of Multiple Gas Analytes.

Colorimetry is widely used in chemical sensing due to its high sensitivity and high selectivity. However, most colorimetric sensors are one-time use because the color-producing reactions or bindings are usually irreversible. In addition, traditional colorimetric sensors like the detection tubes are bulky and packed individually, making parallel sensing of multiple analytes difficult. Here, we demonstrate a gradient-based colorimetric array sensor (GCAS) to overcome these limitations. Different colorimetric sensing elements are inkjet-printed as parallel straight lines on a porous substrate. Lateral transport of analytes across the substrate creates color gradients on the sensing elements. The color gradients shift along the transport direction over time, and GCAS tracks the gradient shifts and converts them into analyte concentrations in real time. Using a low-cost complementary metal-oxide semiconductor imager, we show detection of three air pollutants using a single GCAS chip and 24 h continuous monitoring of ambient ozone.

Monitoring of Ambient Ozone: Instrumentations and Applications

This short review provides the recent progresses on continuous monitoring of atmospheric ozone. The analytical performance is defined in US-EPA 40 CFR Part 53, and Federal Equivalent Method for ozone adopts an ultraviolet photometry to meet the definition. Chemical monitoring systems including spectrophotometry with dye bleaching, chemiluminescence, and bioluminescence have been developed to satisfy the analytical performance. Changes in the electric resistance of semiconductors are also utilized for the measurements. Some of the proposed instruments have been applied to the monitoring of ozone in the ambient air, and reliable results are demonstrated.

Ozone from fireworks: Chemical processes or measurement interference?

Fireworks have been identified as one ozone source by photolyzing NO2 or O2 and are believed to potentially be important for the nighttime ozone during firework events. In this study, we conducted both lab and field experiments to test two types of fireworks with low and high energy with the goal to distinguish whether the visible ozone signal during firework displays is real. The results suggest that previous understanding of the ozone formation mechanism during fireworks is misunderstood. Ultraviolet ray (UV)-based ozone monitors are interfered by aerosols and some specific VOCs. High-energy fireworks emit high concentrations of particular matters and low VOCs that the artificial ozone can be easily removed by an aerosol filter. Low-energy fireworks emit large amounts of VOCs mostly from the combustion of the cardboard from fireworks that largely interferes with the ozone monitor. Benzene and phenol might be major contributors to the artificial ozone signal. We further checked the nighttime ozone concentration in Jinan and Beijing, China, during Chinese New Year, a period with intense fireworks. A signal of 3–8ppbv ozone was detected and positively correlated to NO and SO2, suggesting a considerable influence of these chemicals in interfering with ambient ozone monitoring.

Projection of Ozone-Related Mortality with Climate and Population Changes in Urban China

Background/Aim: China is experiencing rising ozone pollution in urban areas, but its potential future health impacts under both climate and population changes remain unclear. We examine future annual and seasonal ozone-related mortality in 347 urban counties of China under three climate and emission scenarios and six population scenarios. Methods: Ozone projections were statistically downscaled from a global chemistry-climate model to a fine spatial resolution (0.25° × 0.25°) using newly available ambient ozone monitoring data across China from 2013-2015. The attributable fraction method was then applied to estimate the daily ozone-related premature mortality in the 2010s, 2030s, 2040s, and 2050s, respectively. Results: Higher ground-level ozone occurs under an extreme warming scenario in which air pollutant emissions are held at 2005 levels (RCP8.5_WMGG), leading to an excess 4296 (95% CI: 3415 to 5169), 5181 (4213 to 6228), and 5134 (4086 to 6171) non-accidental deaths per year in 2033-2035, 2043-2045, and 2053-2055 relative to 2013-2015. Estimates of future changes in ozone-related mortality are sensitive to the choice of climate and emissions scenario, decreasing under RCP4.5 but increasing under RCP8.5 by 2043-2045 and 2053-2055 relative to 2013-2015. Population increases amplify the adverse impacts of climate change on ozone-related mortality. Deteriorating ozone air quality in colder months contributes to excess ozone-related mortality. Conclusions: Our analysis suggests that more stringent air pollution control measures will be needed, including beyond the warm season, to prevent a rising health burden of climate change via ozone pollution in urban China.

Fast response cavity enhanced ozone monitor

Abstract. Ozone is an important atmospheric gas due to its role in air quality and radiative forcing. A new method for sensitive, rapid monitoring of ambient ozone has been developed using a compact platform and relatively inexpensive components. Based on incoherent broadband cavity enhanced absorption spectroscopy (IBB-CEAS), the device utilizes an optical cavity of just 14.5 cm and 99.3% reflective mirrors. Performance of the instrument has been validated against direct absorption measurements in a single-pass measurement cell. Currently, the IBB-CEAS ozone instrument can achieve ∼1 ppb sensitivities at 0.1 s integration time with a dynamic range over four orders of magnitude, accessing relevant ozone concentrations in both the stratosphere and troposphere. This new device offers improved sensitivity and time response for mapping ozone aboard airborne platforms.

Development and performance evaluation of ozone detection paper using azo dye orange I: Effect of pH

A highly sensitive sensing paper that uses the reaction of ozone with azo dye orange I has been developed for ambient ozone monitoring. This reaction results in reaction products, without absorption in visible region, on paper that can be determined by measuring the reflectance spectrum of the paper. The combination of a cellulose sheet, a humectant (glycerol), an alkali (sodium hydroxide) and orange I is needed to achieve a sensitive sensing paper. We found that the pH of the immersion solution used for preparing the sensing paper had a strong influence on the paper's responsivity to ozone. Ozone detection papers that were made using acidic or neutral immersed solutions were not faded by ozone exposure, whereas those made using a strong alkaline immersion solution were faded by ozone exposure and the color of the paper faded completely at an ozone exposure of about 400 ppb × h. We considered an orange I reaction site for ozone using UV–vis spectrum measurements and molecular orbital calculation by comparing experimental results for both orange I and its isomer orange II. It was estimated that the hydrazone form of orange I in alkaline condition would be sensitive to ozone.

Development and evaluation of ozone detection paper

Abstract A high sensitive paper with good response has been developed for ambient ozone monitoring. The paper operates by employing the reaction of ozone with indigo carmine. This reaction results in white-yellowish reaction products on the paper that can be determined by measuring the paper’s reflectance. Direct, on-site measurements are possible because of the selection of the color change reaction, and only a small photoelectric meter is needed. The combination of a cellulose sheet, humectant, acid and indigo carmine is needed to achieve a good response and the color of our developed ozone detection paper fades completely from blue to white when exposed to ozone concentrations of about 400 ppb × h. The humectant content strongly affects the ozone response, and a 20% glycerol content of the immersed solution yields the best response. We also measured the effects of temperature, relative humidity and wind speed on the ozone response, and found that relative humidity has a strong influence on the ozone response. The interference gases were checked for six chemicals that are usually present in the air, and only hydrogen peroxide exhibited positive interference. Since our developed sensing paper has the good response, it is suitable for hourly to daily mean measurements of ambient ozone and we successfully measured indoor ozone concentrations using our developed ozone detection paper and a photoelectric meter with a single wavelength source.

A New Small Size Digital Optical Ozone Monitor Using CCD Array as a UV Detector

Ozone monitor based on UV techniques has been widely used due to their signal stability. The high concentration ozone monitor for real time ozone monitoring from ozone generator was composed of a low pressure mercury lamp as UV source and a photo multiplier tube as UV detector. The structure could be very useful for low price high concentration ozone monitor and showed good linearity to ozone in the concentration range between 0.05 and 2wt%. For accurate ambient ozone monitoring, the system composed of a high power pulsed xenon lamp as UV source, an optical spectrometer with a high sensitivity linear CCD array as UV detector. The optical signal form the CCD array was converted to digital signal, and the digital signal was displayed on screen using PC interface. The developed system showed good linearity and sensitivity in relatively low measuring range between 10ppm and 10,000ppm, and showed some feasibility of hish resolution ozone monitor using CCD array as a photodetecor.

Measurement of ambient ozone using newly developed porous glass sensor

An accumulated sensor with an hourly resolution has been developed for ambient ozone monitoring. The sensor operates by employing the reaction of ozone with indigo carmine. This reaction results in colorless reaction products in pores that can be determined by measuring the transmittance of the color change. Transparent porous glass is used as a substrate whose very large surface area is an advantage for gas sensing. Direct, on-site measurements are possible because of the use of the transparent substrate, and no chemical analyses are needed. The sensor is used to analyze exposure to ozone. The detection limit of the sensor is about 3 ppb for a 1 h exposure. The interference from nitrogen dioxide amounts to about 25%. The method is suitable for hourly to daily mean measurements of ambient ozone. Under indoor conditions, the correlation coefficient between the hourly ozone concentration indicated by our sensor and by a UV-photometric monitor for 3 months was 0.84, indicating good agreement.

Detecting plant effects is necessary to give biological significance to ambient ozone monitoring data and predictive ozone standards

The use of mechanical monitors and passive samplers has made it possible to assess concentrations of ozone over wide areas and to develop air quality standards, like AOT40 and SUM60. Monitored ozone data and AOT40 and SUM60 are also used to predict ozone injury on local and regional scales. The data and the standards do not include or account for environmental and biological variables that affect ozone uptake and plant injury. Ground proofing via vegetation surveys must be done to verify and validate plant injury predictions. If this is not done, then the standards have no biological significance and are only exercises in air quality assessment.

Ozone sensing using In/sub 2/O/sub 3/-modified Ga/sub 2/O/sub 3/ thin films

It is shown that at elevated temperatures the conductance of an In/sub 2/O/sub 3/-modified Ga/sub 2/O/sub 3/ thin film depends significantly and reversibly on the ozone concentration in the ambient air. This ozone sensitivity is much greater than with pure Ga/sub 2/O/sub 3/ or In/sub 2/O/sub 3/ thin films, respectively. The ozone sensitivity of the In/sub 2/O/sub 3/-modified Ga/sub 2/O/sub 3/ thin film is characterized by an impressive selectivity, and is maximal at an operation temperature of about 600/spl deg/C. The cross sensitivities to other gases present in ambient conditions are small compared to the ozone sensitivity, thus opening the way to use this system for ambient ozone monitoring. The results are discussed using an electron injection model.

Application of gallic acid and xanthene dyes for determination of ozone in air with a chemiluminescence aerosol detector

A fast and sensitive determination of gaseous ozone based on a chemiluminescence reaction with gallic acid and xanthene dyes in the chemiluminescence aerosol detector is described. An optimum reagent solution consists of 0.001 M gallic acid and 0.001 M eosin Y in 10% (v/v) diethylene glycol. The primary chemiluminescence reaction takes place between ozone and gallic acid while eosin Y acts as a sensitizer and diethylene glycol as a modifier. A detection limit of ozone is 0.3 ppb (v/v) and a calibration curve is linear in the range of ozone concentrations 1.4–349 ppb (v/v). Nitrogen dioxide, peroxyacetyl nitrate, formaldehyde, peroxoacetic acid and nitric acid do not interfere. The method, due to its favourable analytical parameters, e.g. linear response and high sensitivity and selectivity, could be used for monitoring of ambient ozone.

Relationships of ozone exposure to pine injury in the Sierra Nevada and San Bernardino Mountains of California, USA

Hourly ambient ozone exposure data and crown injury measurements were gathered in the Sierra Nevada and San Bernardino Mountains of California to develop relationships between the Ozone Injury Index (OII), the Forest Pest Management Index (FPM), chlorotic mottle, fascicle retention (OII index components) and cumulative ambient ozone indices for Pinus ponderosa Dougl. ex Laws and Pinus jeffreyi Grev. and Balf. Eleven sites located in the mixed conifer forest near ambient ozone monitoring sites were evaluated annually for 4 years. Four other sites in the San Bernardino Mountains were evaluated for 1 year. Analyses showed OII to be functionally equivalent ( r 2 = 0.96) to the FPM, and to depend only on fascicle retention and chlorotic mottle ( R 2 = 0.95) of the fourth whorl (or if four whorls are not present at the site, then the last whorl present for the majority of trees). Significant associations were found between OII and 4-year 24-h. summer SUM0, SUM06, W126 and HRS80 ozone indices. Three sites had higher levels of cumulative chlorotic mottle for individual whorls and larger numbers of trees with visible crown injury than other sites with similar cumulative ambient ozone levels. Including an indicator variable to discriminate between these two groups of sites increased R 2 and decreased root mean square (RMSE) for all indices, especially SUM0 ( R 2 = 0.93, RMSE reduced by 46%).