Advances in particle sensor design and manufacturing have enabled the development of low-cost air quality monitors (LCMs). The sensors use light scattering to estimate mass concentration and thus ...require evaluation for aerosols of varied composition and size distribution. We tested the performance of six LCMs designed for home use and having a retail price under US$300 in October 2018. We assessed their performance by comparing their output to reference PM2.5 and PM10 measurements from 21 common residential sources and from infiltrated outdoor PM2.5. Reference data were obtained by using gravimetric measurements to adjust time-resolved output from an aerosol spectrometer with both electrical mobility and optical particle sensors. Compared by linear regression to reference measurements, LCMs had negative intercepts and slopes of 1–2 for infiltrated outdoor PM2.5. Semi-quantitative responses (~50–200% of actual PM2.5) were obtained for varied aerosols including minerals (ultrasonic humidifier, vacuuming, test dust); combustion products (incense, mosquito coil, extinguished candles); microwave popcorn; and cooking involving frying or grilling. LCMs had low or no response to sources for which all mass was in particles smaller than 0.25 μm, including steady candle flames and cooking without frying or grilling. PM10 data from LCMs was more variable than PM2.5.
Display omitted
•“Low-cost” IAQ monitors, LCMs, with optical PM2.5 sensors are available for < US$300.•We tested 6 LCMs +2 pro-grade optical PM2.5 monitors with 21 residential PM sources.•For most sources, LCMs & pro monitors tracked reference PM2.5 within a factor of 2.•Optical sensors miss sources that emit only ultrafine particles.•Some low-cost PM2.5 monitors are suitable for research and managing home IAQ.
Urban air pollution has tremendous spatial variability at scales
ranging from kilometers to meters due to unevenly distributed emission
sources, complex flow patterns, and photochemical reactions. ...However,
high-resolution air quality information is not available through traditional
approaches such as ground-based measurements and regional air quality models
(with typical resolution > 1 km). Here we develop a 10 m
resolution air quality model for traffic-related CO pollution based on the
Parallelized Large-Eddy Simulation Model (PALM). The model performance is
evaluated with measurements obtained from sensors deployed on a taxi
platform, which collects data with a comparable spatial resolution to our
model. The very high resolution of the model reveals a detailed geographical
dispersion pattern of air pollution in and out of the road network. The
model results (0.92 ± 0.40 mg m−3) agree well with the
measurements (0.90 ± 0.58 mg m−3, n=114 502). The model has
similar spatial patterns to those of the measurements, and the r2 value
of a linear regression between model and measurement data is 0.50 ± 0.07 during non-rush hours with middle and low wind speeds. A non-linear
relationship is found between average modeled concentrations and wind speed
with higher concentrations under calm wind speeds. The modeled
concentrations are also 20 %–30 % higher in streets that align with the wind
direction within ∼ 20∘. We find that streets with
higher buildings downwind have lower modeled concentrations at the
pedestrian level, and similar effects are found for the variability in
building heights (including gaps between buildings). The modeled
concentrations also decay fast in the first ∼ 50 m from the
nearest highway and arterial road but change slower further away. This study
demonstrates the potential of large-eddy simulation in urban air quality
modeling, which is a vigorous part of the smart city system and could inform
urban planning and air quality management.
Coronavirus diseases 2019 (COVID-19) is transmitted worldwide in over a very short time, as it was originated in late 2019 from Wuhan city, China. To reduce the possible effects due to COVID-19, some ...sort of lockdown activities have been applied in many countries. In this regard, the outcomes reported bonus benefits to the natural environment showing a significant decrease in air pollution worldwide due to COVID-19. The National Aeronautics and Space Administration (NASA) and European Space Agency (ESA) released air pollution data for Asian and European countries to assess the significant changes in air quality. The main objective of the study is to compare the air quality data released by international agencies before and after the novel coronavirus pandemic.
This research was carried out using the open-source database system along with the continuous air quality monitoring station results from global data sets during the COVID-19 pandemic lockdown in ...India and the global. Our purpose of this research is to study the improvement of air quality and human mortality rates in countries worldwide during the COVID-19 pandemic lockdown. Worldwide air quality data were collected from > 12,000 continuous air quality monitoring stations on six continents covering 1000 major cities from over 100 countries. Here, we discussed the implementation of the open-source data set of basic air pollutants such as PM 2.5, NO
2
, temperature, relative humidity, and Air Quality Index variation during the pre-lockdown and lockdown pandemic COVID-19 in India and described the global aspect. An average concentration of PM 2.5 (145.51 μg/m
3
), NO
2
(21.64 μg/m
3
), and AQI index (55.58) continuously decreased. The variation of PM 2.5, NO
2
, normally shows more than 25 μg/m
3
every year, but during the COVID-19 lockdown period (April 2020) continuously decreased below 20 μg/m
3
. Similarly, the AQI index and meteorological factors such as temperature, relative humidity, and wind speed variation decreased significantly in the many countries in the world. In Asian countries, air quality improved during the national lockdown especially in the most polluted cities globally such as Beijing, Delhi, and Nanjing and also in developed cities like Madrid, New York, Paris, Seoul, Sydney, Tokyo. Furthermore, the reduction of particulate matter was in about 46%, and other gaseous pollutants during the lockdown period were observed in a 54% reduction. We are witnessing pollution reductions which add significantly to improvements in air quality. This is due to the massive decrease in the use of fossil fuel, which in turn reduces production and traffic in general. People nowadays are now willing to see a comparatively healthier world with bleached skies and natural ecosystems. This research finding demonstrates potential safety benefits associated with improving air quality and mortality rates during the COVID-19 pandemic, resulting in decreases in mortality rates in India and around the world.
The growing populations around the world are closely associated with rising levels of air pollution. The impact is not restricted to outdoor areas. Moreover, the health of building occupants is also ...deteriorating due to poor indoor air quality. As per the World Health Organization, indoor air pollution is a leading cause of 1.6 million premature deaths annually. Therefore, numerous companies have started the development of low-cost sensors to monitor indoor air pollution with the Internet of Things–based applications. However, due to the close association of air pollution levels to the mortality and morbidity rates, communities face several limitations while selecting sensors to address this public health challenge. The main contribution of this systematic review is to present a qualitative and quantitative evaluation of low-cost sensors while providing deep insights into the selection criteria for adequate monitoring. The authors in this paper discussed studies published after the year 2015, and it includes an analysis of papers published in the English language only. Moreover, this study highlights crucial research questions, states answers, and provides recommendations for future research studies. The outcomes of this paper will be useful for students, researchers, and industry members concerning the upcoming research and manufacturing activities. The results show that 28 studies (70%) include indoor thermal comfort assessment, 26 (65%) and 12 (30%) studies include CO
2
and CO sensors, respectively. In total, 32 (45.7%) out of 71 sensors (whose prices are available) discussed in this study are available in a price below the US $20 over online marketplaces. Furthermore, the authors conclude that 77.5% of the analyzed literature does not include calibration details, and the accuracy specification is missing for 39.4% sensors.
In major cities, air quality is of significant concern because of its negative effect on the health of the region’s living conditions, climate, and economy. Recent studies show the significance of ...the data on microlevel pollution which includes severe air pollutants and their impacts on human. Conventional methods of measuring air quality need skilled personnel for accurate data measurement that are based on stationary and limited measuring station networks. However, it is costly to seize the spatio-temporal variability and to recognize pollution hotspots that are necessary to develop real-time exposure control strategies. Due to the restricted accessibility of information and the non-scalability of standard techniques for air pollution monitoring, a real-time system with both higher spatial and temporal resolution is crucial. In recent times, unmanned aerial vehicles (UAVs) mounted with various sensors have been implemented for on-site air quality surveillance as they can offer new methods and research possibilities in air pollution and emission tracking, as well as in the study of environmental developments. An extensive literature review has been conducted, and it was observed that there are types of UAVs and types of sensors that are used for air quality monitoring for the parameters like CO, SO
2
, NO
2
, O
3
, PM
2.5
, PM
1.0
, and black carbon. Low-cost wireless sensors have been using for monitoring purpose in the past studies, and when results obtained are validated with the stationary monitoring instruments, the coefficient of correlation (
R
2
) is found to be varied from 0.3 to 0.9. The difficulties, however, are not just technical, but at present time, policies and laws, which vary from country to country, symbolize the major challenge to the extensive use of UAVs in air quality/monitoring studies.
Urban air quality is one of the most prominent
environmental concerns for modern city residents and authorities. Accurate
monitoring of air quality is difficult due to intrinsic urban landscape
...heterogeneity and superposition of multiple polluting sources. Existing
approaches often do not provide the necessary spatial details and peak
concentrations of pollutants, especially at larger distances from monitoring
stations. A more advanced integrated approach is needed. This study presents
a very high-resolution air quality assessment with the Parallelized Large-Eddy Simulation Model (PALM), capitalising on local measurements. This fully three-dimensional
primitive-equation hydrodynamical model resolves both structural details of
the complex urban surface and turbulent eddies larger than 10 m in size. We
ran a set of 27 meteorological weather scenarios in order to assess the
dispersion of pollutants in Bergen, a middle-sized Norwegian city embedded
in a coastal valley. This set of scenarios represents typically observed
weather conditions with high air pollution from nitrogen dioxide (NO2)
and particulate matter (PM2.5). The modelling methodology helped to
identify pathways and patterns of air pollution caused by the three main
local air pollution sources in the city. These are road vehicle traffic,
domestic house heating with wood-burning fireplaces and ships docked in the
harbour area next to the city centre. The study produced vulnerability maps,
highlighting the most impacted districts for each weather and emission
scenario. Overall, the largest contribution to air pollution over inhabited
areas in Bergen was caused by road traffic emissions for NO2 and
wood-burning fireplaces for PM2.5 pollution. The effect of emission
from ships in the port was mostly restricted to the areas close to the
harbour and moderate in comparison. However, the results have contributed to
implementation of measures to reduce emissions from ships in Bergen harbour,
including provision of shore power.
The COVID-19 pandemic caused a setback for Nepal, leading to nationwide lockdowns. The study analyzed the impact of lockdown on air quality during the first and second waves of the COVID-19 pandemic ...in the Kathmandu Valley. We analyzed 5 years of ground-based air quality monitoring data (2017–2021) from March to July and April to June for the first and second wave lockdowns, respectively. A significant decrease in PM
2.5
(particulate matter with an aerodynamic diameter ≤ 2.5 μm) concentrations was observed during the lockdowns. The highest rate of decline in PM
2.5
levels was observed during May and July compared to the pre-pandemic year. The PM
2.5
concentration during the lockdown period remained within the WHO guideline limit and NAAQS for the maximum number of days compared to the lockdown window in the pre-pandemic years (2017–2019). Likewise, lower PM
2.5
levels were observed during the second wave lockdown, which was characterized by a targeted lockdown approach (smart lockdown). We found a significant correlation of PM
2.5
concentration with community mobility changes (i.e., walking, driving, and using public transport) from the Spearman correlation analysis. Lockdown measures restricted human mobility that led to a lowering of PM
2.5
concentrations. Our findings can be helpful in developing urban air quality control measures and management strategies, especially during high pollution episodes.
The Mexico City Metropolitan Area has an expansive urban population and a long history of air quality management challenges. Poor air quality has been associated with adverse pulmonary and cardiac ...health effects, particularly among susceptible populations with underlying disease. In addition to reducing pollution concentrations, risk communication efforts that inform behavior modification have the potential to reduce public health burdens associated with air pollution.
This study investigates the utilization of Mexico's IMECA risk communication index to inform air pollution avoidance behavior among the general population living in the Mexico City Metropolitan Area. Individuals were selected via probability sampling and surveyed by phone about their air quality index knowledge, pollution concerns, and individual behaviors.
The results indicated reasonably high awareness of the air quality index (53% of respondents), with greater awareness in urban areas, among older and more educated individuals, and for those who received air quality information from a healthcare provider. Additionally, behavior modification was less influenced by index reports as it was by personal perceptions of air quality, and there was no difference in behavior modification among susceptible and non-susceptible groups.
Taken together, these results suggest there are opportunities to improve the public health impact of risk communication through an increased focus on susceptible populations and greater encouragement of public action in response to local air quality indices.
Exposure to fine particulate matter (PM
2.5
) is known to harm public health. In China, after implementation of aggressive emissions control measures under the Action Plan of Air Pollution Prevention ...and Control (2013–2017), air quality has significantly improved. In this work, we investigated changes in PM
2.5
exposure and the associated health impacts in China for the period 2013–2017. We used an optimal estimator of PM
2.5
combining
in-situ
observations, satellite measurements, and simulations from a chemical transport model to derive the spatial and temporal variations in PM
2.5
exposure, and then used well-developed exposure-response functions to estimate the premature deaths attributable to PM
2.5
exposure. We found that national population-weighed annual mean PM
2.5
concentrations decreased from 67.4 µg m
−3
in 2013 to 45.5 µg m
−3
in 2017 (32% reduction). This rapid decrease in PM
2.5
pollution led to a 14% reduction in premature deaths due to long-term exposure. We estimated that, during 2013–2017, the premature deaths attributable to long-term PM
2.5
exposure decreased from 1.2 million (95% CI: 1.0, 1.3; fraction of total mortality: 13%) in 2013 to 1.0 million (95% CI: 0.9, 1.2; 10%) in 2017. Despite the rapid decrease in annual mean PM
2.5
concentrations, health benefits associated with reduced long-term exposure were limited, because for many cities, the PM
2.5
levels remain at the portion where the exposure-response function is less steeper than that at the low-concentration end. We also found that the deaths associated with acute exposure decreased by 61% during 2013–2017 due to rapid reduction in the number of heavily polluted days. Our results confirm that clean air policies in China have mitigated the air pollution crisis; however, continuous emissions reduction efforts are required to protect citizens from air pollution.
PDF
