Tropical Coastal City Research Articles

Plant diversity value of informal green spaces in tropical coastal urban areas: An empirical study of species, functional, and phylogenetic diversity

Informal green spaces (IGS) are a hot topic in urban biodiversity studies, but overlooked in urban biodiversity conservation or management, especially in tropical coastal cities, where comprehensive assessments remain scarce. Most existing research has been limited to species diversity (α-diversity), with few studies addressing functional and phylogenetic diversity as aspects of α-diversity, and species turnover (β-diversity) across multiple IGS types. This study bridges these gap by conducting a detailed vegetation survey in Jiangdong New Area of Haikou City, establishing 213 sites. Within these sites, we examined 343 IGS sample plots and 274 formal green spaces (FGS) sample plots. We assessed species, functional, and phylogenetic diversity using α and β diversity metrics and analyzed the influence of environmental factors with generalized linear mixed models (GLMMs). The results recorded 235 species of herbaceous plants from 179 genera and 54 families in IGS, including 215 spontaneous species, compared to 154 spontaneous species in FGS. Our findings indicate that IGS exhibited higher species richness and functional richness compared to FGS, though differences in phylogenetic diversity were less pronounced. Key environmental factors like relative humidity, trampling intensity, and proximity to urban areas significantly influenced species richness and abundance in IGS. These findings underscore the critical role of IGS in enhancing biodiversity and resilience in tropical coastal cities, emphasizing the need to integrate IGS into urban planning strategies for sustainable urban ecosystems.

Revolutionizing travel experiences: An in-depth analysis of intelligent booking systems and behavioral patterns

This study delves into the intricacies of booking behaviors, focusing on the preference for tropical coastal cities during colder seasons, given the burgeoning need for personalized and intelligent travel recommendations in the modern tourism landscape. Traditional booking systems, with their static algorithms, have often neglected the dynamic interplay of environmental factors and user preferences, necessitating an evolution towards more sophisticated, adaptive models. To address this, the research employed advanced machine learning and artificial intelligence techniques, amalgamating data from diverse sources like major tourism websites, hotel platforms, and social media. The methodology involved meticulous data preprocessing to ensure data quality and depth, followed by the implementation of deep learning models and time series analysis, which were instrumental in deciphering complex patterns and offering predictive insights. This comprehensive approach facilitated the integration of various environmental factors such as weather conditions and temporal events, enabling the system to craft hyper-personalized recommendations that resonate with user preferences and environmental nuances. The findings were illuminating, unveiling a significant inverse relationship between temperature and bookings and highlighting the influential role of temporal events in driving bookings. The advanced predictive models showcased commendable accuracy, underscoring the transformative potential of such intelligent systems in enhancing user experiences and engagement in the tourism sector. These insights pave the way for the development of innovative strategies that can significantly elevate user satisfaction and industry growth. The study concludes that the integration of machine learning and AI in booking systems can revolutionize the tourism industry by offering unprecedented levels of personalization and adaptability, catering to the diverse and evolving needs of modern travelers.

PM2.5 pollution modulates the response of ozone formation to VOC emitted from various sources: Insights from machine learning

Numerous studies have linked ozone (O3) production to its precursors and fine particulate matter (PM2.5), while the complex interaction effects of PM2.5 and volatile organic compounds (VOCs) on O3 remain poorly understood. A systematic approach based on an interpretable machine learning (ML) model was utilized to evaluate the primary driving factors that impact O3 and to elucidate how changes in PM2.5, VOCs from different sources, NOx, and meteorological conditions either promote or inhibit O3 formation through their individual and synergistic effects in a tropical coastal city, Haikou, from 2019 to 2020. The results suggest that under low PM2.5 levels, alongside the linear O3-PM2.5 relationship observed, O3 formation is suppressed by PM2.5 with higher proportions of traffic-derived aerosol. Vehicle VOC emissions contributed maximally to O3 formation at midday, despite the lowest concentration. VOCs from fossil fuel combustion and industry emissions, which have opposing effects on O3, act as inhibitors and promoters by inducing diverse photochemical regimes. As PM2.5 pollution escalates, the impact of these VOCs reverses, becoming more pronounced in shaping O3 variation. Sensitivity analysis reveals that the O3 formation regime is VOC-limited, and effective regional O3 mitigation requires prioritizing substantial VOC reductions to offset enhanced VOC sensitivity induced by the co-reduction in PM2.5, with a focus on industrial and vehicular emissions, and subsequently, fossil fuel combustion once PM2.5 is effectively controlled. This study underscores the potential of the SHAP-based ML approach to decode the intricate O3-NOx-VOCs-PM2.5 interplay, considering both meteorological and atmospheric compositional variations.

Threats faced by native fishes in tropical coastal cities: A case study of Sanya City, Hainan Province, China

Threats faced by native fishes in tropical coastal cities: A case study of Sanya City, Hainan Province, China

Analyzing the Effect of Air Pollutants on Particulate Matter Concentrations of the Tropical coastal city of Thiruvananthapuram, India by Wavelet Coherence

The main environmental risk factor that need regular monitoring and analysis for efficient air quality management is particulate matter (PM). This paper analyzes the effect of gaseous air pollutants (SO2, CO, Ozone, NOx) on PM concentration in the coastal city of Thiruvananthapuram, India using Wavelet coherence (WTC). The study was conducted using the data from Plammoodu station of the city for the period of 2018 to 2021. The teleconnections of air pollutants with PMs are analysed using WTC for the data of different time spells of 2018-2021, 2018 and 2020. Results showed that among the air pollutants, Ozone (AWC of 0.4713 & PoSC of 23.0234 for PM10, AWC of 0.4814 & PoSC of 26.2261 for PM2.5) have most dominant influence on irrespective of the particulate matter type and time spells. The secondary influencing factors were found to be different with respect to the time spells chosen, indicating the dynamics of local variables on PM concentrations of the city.

Habitat heterogeneity explains cultivated and spontaneous plant richness in Haikou City, China

Recent urbanization and human activities have led to the fragmentation of natural landscape patches and reduced the connectivity and degradation of urban ecosystems and biodiversity. Urban plant richness affects social functions and the well-being of urban residents and is driven by land use, local wealth, and urban green space management. Among these drivers, it remains unclear which factors play a more important role in driving the relative diversity of cultivated and spontaneous plant species richness in cities. Therefore, we investigated the spatial patterns and the drivers of cultivated and spontaneous plant species richness within 190 urban functional units (UFUs) in the tropical coastal city of Haikou, China, based on remote sensing data, fieldwork, and surveys of socioeconomic and greening management practices. Using multiple linear regression, we found that the most cultivated plants were located at colleges and universities, public affair service districts, and around hospitals, while the most spontaneous plants were found in transportation districts. The spatial organization of these plants was influenced by factors such as patchiness, connectivity, maintenance frequency and fertilizing frequency. Cultivated plants, conversely, were found to increase with patchiness and connectivity, and their presence was positively related to fertilizing and maintenance frequency. The richness of both spontaneous and cultivated plants was found to be influenced by various factors among different urban functional units (UFUs). The proximity to freshwater resources was found to increase the number of spontaneous plant species. Our findings underscore the significant impact of human activities on urban plant richness and highlight the importance of understanding these dynamics for urban planning and biodiversity conservation. Our work contributes to the scarce literature on the drivers of cultivated and spontaneous plant richness in recently developed tropical cities.

What impacts ecosystem services in tropical coastal tourism cities? A comparative case study of Haikou and Sanya, China

The ecological environment of tourism-oriented towns is attracting increasing attention. Taking the cities of Haikou and Sanya as examples, we examined changes in six ecosystem services (ES), including water conservation (WC), crop production (CP), soil retention (SR), carbon storage (CS), habitat quality (HQ), and tourism recreation (TR) from 2005 to 2020. From the three perspectives of geographical environment, socioeconomic development, and tourism development force, 14 indicators were chosen to examine the impact on ES. Except for Haikou's TR, the other ES of Haikou and Sanya showed a decreasing trend from 2005 to 2020. The values of six ES were lower in coastal zones than in noncoastal zones, which were more obvious in Sanya. Specifically, the areas of low value in Sanya were concentrated in the coastal region, and the areas with low value in Haikou were primarily distributed in blocks along the coast and in bands or points in the central and southern areas. From the perspective of influencing factors, the natural environmental factors dominate in Haikou, followed by the socio-economic factors and finally the tourism development factors, while the natural environmental factors also dominate in Sanya, followed by the tourism development factors and finally the socio-economic factors. We provided recommendations for sustainable tourism development in Haikou and Sanya. This study has significant implications for both integrated management and scientific decision-making to enhance the ES of tourism destinations.

Exploring the Meteorological Impacts of Surface and Rooftop Heat Mitigation Strategies Over a Tropical City

AbstractDifferent heat mitigation technologies have been developed to improve the thermal environment in cities. However, the regional impacts of such technologies, especially in the context of a tropical city, remain unclear. The deployment of heat mitigation technologies at city‐scale can change the radiation balance, advective flow, and energy balance between urban areas and the overlying atmosphere. We used the mesoscale Weather Research and Forecasting model coupled with a physically based single‐layer urban canopy model to assess the impacts of five different heat mitigation technologies on surface energy balance, standard surface meteorological fields, and planetary boundary layer (PBL) dynamics for premonsoon typical hot summer days over a tropical coastal city in the month of April in 2018, 2019, and 2020. Results indicate that the regional impacts of cool materials (CMs), super‐cool broadband radiative coolers, green roofs (GRs), vegetation fraction change, and a combination of CMs and GRs (i.e., “Cool city (CC)”) on the lower atmosphere are different at diurnal scale. Results showed that super‐cool materials have the maximum potential of ambient temperature reduction of 1.6°C during peak hour (14:00 LT) compared to other technologies in the study. During the daytime hours, the PBL height was considerably lower than the reference scenario with no implementation of strategies by 700 m for super‐cool materials and 500 m for both CMs and CC cases; however, the green roofing system underwent nominal changes over the urban area. During the nighttime hours, the PBL height increased by CMs and the CC strategies compared to the reference scenario, but minimal changes were evident for super‐cool materials. The changes of temperature on the vertical profile of the heat mitigation implemented city reveal a stable PBL over the urban domain and a reduction of the vertical mixing associated with a pollution dome. This would lead to crossover phenomena above the PBL due to the decrease in vertical wind speed. Therefore, assessing the coupled regional impact of urban heat mitigation over the lower atmosphere at city‐scale is urgent for sustainable urban planning.

Precipitation frequency controls nitrogenous aerosol in a tropical coastal city and its implications for plant carbon sequestration

The concentration of nitrogenous aerosols is influenced by air mass transition, local meteorological conditions, local emissions, and the wet removal effect driven by precipitation. Deposited nitrogenous aerosols influence nitrogen availability in the canopy, affecting the amount of plant carbon sequestration. However, the factors controlling nitrogenous aerosol concentrations and their implications for plant carbon sequestration remain unclear. In this study, multiple stable nitrogen isotopes in atmospheric aerosols (δ15N-TN, δ15N–NO3–, and δ15N–NH4+) and rainwater (rainwater δ15N–NO3– and rainwater δ15N–NH4+) in one-year observations were analyzed to explore the main factors controlling nitrogenous aerosol concentrations. The results showed that NO3− and NH4+ were the major components of TN, and their concentrations in seasonal patterns were sensitive to frequent rainfall rather than local emissions or external contributions. The concentrations of nitrogenous aerosols were negatively correlated with precipitation frequency, indicating that increased precipitation frequency induced low concentrations of nitrogenous aerosols. Moreover, the positive matrix factorization (PMF) analysis showed that coarse mode NO3− was generated in the wet season but not in the dry season, reflecting the removal of precipitation. With the increased precipitation frequency from May to July, 42.4% of aerosol NO3− was scavenged into rainwater, indicated by the variations in the δ15N values of nitrogenous aerosols and rainwater. This result prompted us to calculate the loss of 12.1 ± 3.9 Gg carbon/yr plant carbon sequestration. Our study suggests that nitrogenous aerosols are captured by the high precipitation frequency in tropical areas, decreasing nitrogen availability in the canopy, which might decrease plant carbon sequestration.

Impact of Building Energy Mitigation Measures on Future Climate

As cities are increasing technological efficacy on greenhouse gas (GH) emission reduction efforts, the surrounding urban ecosystems and natural resources may be affected by these measures. In this research, climate indicators such as heat index, extreme heat events, intensified urban heat islands (UHIs), and sea breeze are projected for the middle and end of the 21st century to understand the climate change signal on these variables with and without building energy mitigation measures. Cities amplify extreme heat and UHI impacts by concentrating large populations and critical infrastructure in relatively small areas. Here, we evaluate the combined climate and building energy mitigation impacts on localized climate metrics throughout the 21st century across extreme emission scenarios (RCP8.5) for the tropical coastal city of San Juan. The analysis of statistically downscaled global circulation model outputs shows underestimation for uncorrected summer daily maximum temperatures, leading to lower extreme heat intensity and duration projections from the present time which are corrected using bias-corrected techniques. High-resolution dynamic downscaling simulations reveal a strong dependency of changes in extreme heat events in urban settings, however, the intensities shift to lower-level grasslands and croplands with energy mitigation measures (combination of white roof, tilted photovoltaic roof, and efficient heating ventilation and air conditioning systems). The building energy mitigation measures have the potential of reducing the UHI intensities to 1 °C and 0.5 °C for the 2050 and 2100 climate periods, respectively.

Regime shift in aerosol ammonium between the rainy and dry season: Perspective from stable isotopes in bulk deposition

Atmospheric ammonia (NH3) is a precursor of the ammonium (NH4+) in rainwater and aerosol. However, relations among them are largely unknown, which preventing our understanding from the sources and spatio-temporal variability of the NH4+ in rainwater and aerosol. Concentration and stable nitrogen isotope (δ15N) of NH4+ were measured in bulk deposition to reveal the relations between rainwater-NH4+ and aerosol-NH4+ and identify NH3 sources in a tropical coastal city, Zhanjiang. During the dry season, δ15N values of NH4+ in the aerosol (aerosol-δ15N–NH4+) were enriched with increased air temperature and consistently heavier than those in the rainwater (rainwater-δ15N–NH4+), suggesting that relatively high air temperature in the tropics were dominant regulator in the dry season. The negative correlation in the Rayleigh model also evidenced that air temperature caused a kinetic fractionation (fractionation effect: −4.8 ± 0.7‰) in aerosol. By contrast, rainfall was a dominant factor on aerosol and rainwater in the rainy season, as suggested by the progressively enriched aerosol-δ15N–NH4+ and depleted rainwater-δ15N–NH4+. These scenarios were ascribed to isotopic exchange (fractionation effect: +1.0 ± 0.4‰), indicating by positive coefficients in the Rayleigh model. After considering the isotopic fractionation in aerosol, the major sources of NH3 in Zhanjiang calculated by the SIAR mixing model were volatilization of livestock waste and fertilizer (>95% in both season), followed by fossil fuel combustion (2% in the rainy season and 3% in the dry season), and biomass burning (1% in the rainy season and 1% in the dry season).

Wealth and land use drive the distribution of urban green space in the tropical coastal city of Haikou, China

Urban green spaces (UGSs) provide a plethora of ecosystem services that benefit humans and wildlife within cities. UGS both promotes and is affected by overall urban ecological health, which can be measured by a wide range of indices. In this study, we investigated the distribution patterns and drivers of UGS within the tropical coastal city of Haikou, Hainan, China over the past decade using a combination of remote sensing data and field work. We interpreted Google earth images from 2010 and 2020 to determine the land cover of UGS within Urban Functional Units (UFUs). We collected socioeconomic variables to test if wealth, site age, and land use determine the proportion of UGS in the city. We found that the proportion of UGS in parks was the highest among all UFUs in 2010 and 2020. In general, UGS increased with maintenance frequency and housing price, which are proxies for the luxury effect. However, land use also played a role in UGS distribution across UFUs, especially in transportation areas, recreation and leisure districts, and residential districts. Haikou is similar to other cities in showing a positive luxury effect on the distribution of UGS. Our results highlight the key roles that parks, colleges and universities, and research institute areas have played in maintaining stable green space within Haikou over the past decade. We suggest that relatively recently implemented governmental programs to increase green space elsewhere in the city may not yet have achieved success within the time span that we analyzed.

Predictive modelling of land use land cover dynamics for a tropical coastal urban city in Kerala, India

Predictive modelling of land use land cover dynamics for a tropical coastal urban city in Kerala, India

Solar Radiation Components on a Horizontal Surface in a Tropical Coastal City of Salvador

Renewable energy must be prioritized by humankind, mainly if there is an expected increase of 50% in energy consumption by 2030 and climate change scenarios are also confirmed. Urban areas consume 70% of the available energy on the planet. Brazil, the largest country in South America, concentrates more than 85% of its population in urban areas, facing a challenge to increase the renewable power plants in its energy matrix. This work presents the solar radiation components behavior for the city of Salvador to contribute with initiatives for the use of solar energy resource. Firstly, a radiometric platform was implemented to obtain direct measurements of global (EG) and diffuse (EDF) components of incoming solar radiation at the surface. The knowledge of EDF is an important requirement to support photovoltaic system projects, and there is no information on direct measurements of this component in the State of Bahia. The diffuse radiation measurement device (DRMD) was designed and built for this purpose. The measurements of solar radiation components performed in this research were submitted to a specific quality control, statistically analyzed and used to evaluate the performance of different empirical models to represent the behavior of EDF in the tropical coastal city. The results demonstrate the potential to explore solar energy in the city of Salvador, with annual values of sunshine higher than 2200 h year−1 and average daily intensities of EG and EDF equal to 18.7 MJm−2day−1 and 7.35 MJm−2day−1, respectively. The analysis of the diurnal cycle shows that EG in summer reaches a maximum of 4.2 MJm−2h−1 and in the rainy season it reaches a minimum of 3.7 MJm−2h−1, both at noon, and in summer the EDFh is 35% of the EGh and it is 46% in the rainy season.

Drivers of spontaneous and cultivated species diversity in the tropical city of Zhanjiang, China

Urban plant diversity influences the social functioning and well-being of urban dwellers. However, the patterns and drivers of plant diversity in tropical urban areas are still not entirely understood. In response to the knowledge deficiencies in this area, we investigated spontaneous and cultivated plant richness and their phylogenetic diversity and relatedness in 260 Urban Functional Units (UFUs), which represented nine different land use types according to anthropogenic function, in the tropical coastal city of Zhanjiang, China. Plant diversity was modelled as a function of UFU characteristics and human maintenance practices. Spontaneous species richness was highest in urban villages and vacant lands and lowest in transportation areas, while phylogenetic diversity was highest in utilities and lowest in parks. In comparison, cultivated species richness was highest in multi-family residential areas and lowest in vacant lands, while phylogenetic diversity of cultivated species was highest in commercial/industry areas and lowest in agriculture areas. The number of cultivated species and the degree of phylogenetic relatedness of spontaneous species were positively correlated with the human population density. The phylogenetic diversity of cultivated species within UFUs was generally higher than that of spontaneous species. Human maintenance of landscapes acted as an environmental filter for spontaneous species, but also promoted the number of cultivated plants. We conclude that appropriate investment in urban green areas may improve both plant species richness and phylogenetic diversity in urban environments.

Impact of urbanization on boundary-layer parameters and mesoscale circulations over tropical coastal city, Chennai

Impact of urbanization on boundary-layer parameters and mesoscale circulations over tropical coastal city, Chennai

Antagonistic effects of seawalls and urban sedimentation on epilithic algal matrix (EAM)-feeding fishes

Marine urbanisation often results in the proliferation of artificial coastal defences and heavy sedimentation, adversely impacting coral reef systems in tropical coastal cities. Knowledge of how motile organisms, such as reef fish, respond to novel human-made habitats and high sedimentation is limited. Here, we examine the role of sloping granite seawalls in supporting reef fishes that utilise the epilithic algal matrix (EAM) as a food resource. We surveyed fish assemblages and feeding activities on seawalls and reef flats, and conducted a field experiment to examine the effects of sediment on EAM feeding rates. Seawalls and reef flats supported distinct fish assemblage composition with significantly greater feeding activity on seawalls. However, reduced feeding activity on EAM with elevated sediment loads suggests that urban sedimentation may limit the utility of this novel feeding ground for nearshore communities. These findings illustrate the complexities and interactive effects of anthropogenic changes driven by coastal urbanisation.

Positive relationships among aboveground biomass, tree species diversity, and urban greening management in tropical coastal city of Haikou.

Within urban green spaces, tree species diversity is believed to correlate with aboveground biomass, though there is some disagreement within the literature on the strength and directionality of the relationship. Therefore, we assessed the relationship between the biodiversity of woody species and the aboveground biomass of woody plant species in the tropical, coastal city of Haikou in southern China. To accomplish this, we obtained comprehensive tree and site data through field sampling of 190 urban functional units (UFUs, or work units) corresponding to six types of land uses governmental‐institutional, industrial‐commercial, park‐recreational, residential, transport infrastructure, and undeveloped area. Based on our field data, we investigated the relationship between tree species diversity and aboveground biomass using multiple regression, which revealed significant relationships across all five types of land uses. Aboveground biomass in green spaces was also correlated with anthropogenic factors, especially time since urban development, or site age, annual maintenance frequency by human caretakers, and human population density. Among these factors, maintenance is the strongest predictor of aboveground biomass in urban green space. Therefore, this study highlights the critical role of maintenance of urban green space in promoting both aboveground biomass and woody biodiversity in urban ecosystems and, consequently, on urban ecosystem services. Our findings contribute to a deeper understanding of the ecosystem services provided by communities of woody plant species in urban areas.

Mitigation Options to Reduce Peak Air Temperature and Air-Conditioning Demand in the Context of a Warming Climate for a Tropical Coastal City

Abstract Air conditioning (AC) demand has recently grown to about 10% of total electricity globally, and the International Energy Agency (IEA) predicts that the cooling requirement for buildings globally increases by three-fold by 2050 without additional policy interventions. The impacts of these increases for energy demand for human comfort are more pronounced in tropical coastal areas due to the high temperatures and humidity and their limited energy resources. One of those regions is the Caribbean, where building energy demands often exceed 50% of the total electricity, and this demand is projected to increase due to a warming climate. The interconnection between the built environment and the local environment introduces the challenge to find new approaches to explore future energy demand changes and the role of mitigation measures to curb the increasing demands for vulnerable tropical coastal cities due to climate change. This study presents mid-of-century and end-of-century cooling demand projections along with demand alleviation measures for the San Juan Metropolitan Area in the Caribbean Island of Puerto Rico using a high-resolution configuration of the Weather Research and Forecasting (WRF) model coupled with Building Energy Model (BEM) forced by bias-corrected Community Earth Systems Model (CESM1) global simulations. The World Urban Database Access Portal Tool (WUDAPT) Land Class Zones (LCZs) bridge the gap required by BEM for their morphology and urban parameters. MODIS land covers land use is depicted for all-natural classes. The baseline historical period of 2008–2012 is compared with climate and energy projections in addition to energy mitigation options. Energy mitigation options explored include the integration of solar power in buildings, the use of white roofs, and high-efficiency heating, ventilation, and air conditioning (HVAC) systems. The impact of climate change is simulated to increase minimum temperatures at the same rate as maximum temperatures. However, the maximum temperatures are projected to rise by 1–1.5 °C and 2 °C for mid- and end-of-century, respectively, increasing peak AC demand by 12.5% and 25%, correspondingly. However, the explored mitigation options surpass both increases in temperature and AC demand. The AC demand reduction potential with energy mitigation options for 2050 and 2100 decreases the need by 13% and 1.5% with the historical periods. Overall, the demand reduction potential varies with LCZs showing a high reduction potential for sparsely built (32%), and low for compact low rise (21%) for the mid-of-century period compared with the same period without mitigation options.

Influence of the seasonality and of urban variables in the BTEX and PM2.5 atmospheric levels and risks to human health in a tropical coastal city (Fortaleza, CE, Brazil).

The International Agency for Research on Cancer (IARC) classifies benzene in group 1 (carcinogenic to humans). Particulate matter (PM) has recently also been classified in this category. This was an advance toward prioritizing the monitoring of particles in urban areas. The aim of the present study was to assess levels of PM2.5 and BTEX (benzene, toluene, ethylbenzene, and xylene), the influence of meteorological variables, the planetary boundary layer (PBL), and urban variables as well as risks to human health in the city of Fortaleza, Brazil, in the wet and dry periods. BTEX compounds were sampled using the 1501 method of NIOSH and determined by GC-HS-PID/FID. PM2.5 was monitored using an air sampling pump with a filter holder and determined by the gravimetric method. Average concentrations of BTEX ranged from 1.6 to 45.5μgm-3, with higher values in the wet period, which may be explained by the fact that annual distribution is influenced by meteorological variables and the PBL. PM2.5 levels ranged from 4.12 to 33.0μgm-3 and 4.18 to 86.58μgm-3 in the dry and wet periods, respectively. No seasonal pattern was found for PM2.5, probably due to the influence of meteorological variables, the PBL, and urban variables. Cancer risk ranged from 2.46E-04 to 4.71E-03 and 1.72E-04 to 2.01E-03 for benzene and from 3.07E-06 to 7.04E-05 and 3.08E-06 to 2.85E-05 for PM2.5 in the wet and dry periods, respectively. Cancer risk values for benzene were above the acceptable limit established by the international regulatory agency in both the dry and wet periods. The results obtained of the noncarcinogenic risks for the compounds toluene, ethylbenzene, and xylene were within the limits of acceptability. The findings also showed that the risk related to PM is always greater among smokers than nonsmokers.