Comparative Effects of Ammonium and Nitrate Compounds on Pacific Treefrog and African Clawed Frog Embryos

The effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of Pacific treefrog (Pseudacris regilla) and African clawed frog (Xenopus laevis) embryos were determined in static-renewal tests. The 10-day LC50s for the three ammonium compounds for P. regilla ranged from 25.0–32.4 mg/L NH₄ -N. The 10-day sodium nitrate LC50 for P. regilla was 578.0 mg/L NO₃-N. LC50s for X. laevis exposed for 4 or 5 days to the three ammonium compounds ranged from 27.5–60.2 mg/L NH₄-N. The sodium nitrate LC50 for X. laevis ranged from 438.4–871.6 mg/L NO₃-N. The lowest LOAEL based on length or weight was 6.1 mg/L NH₄-N for the two species. The lowest LOAELs for NO₃-N were 111.1 mg/L for P. regilla and 56.7 mg/L for X. laevis. Calculated unionized NH₃ comprised 0.5–1.8% of measured NH₄-N concentrations. Potential harm to amphibian populations could occur if NH₄-N and NO₃-N in agricultural runoff or drainage impacts sensitive life stages for a sufficiently long period. Received: 9 April 1998/Accepted: 16 August 1998     

Assessment of nonpoint source pollution in stormwater runoff in Louisville, (Jefferson County) Kentucky,USA

First flush (first 20 min) and composite (first 3 h) samples of stormwater runoff were collected during a 1-year period (1991–1992) from six sites in the Louisville, Kentucky (USA), metropolitan area. Each collection was analyzed for organic and inorganic compounds, pesticides, nutrients, dissolved solids, dissolved oxygen, turbidity, alkalinity, conductivity, hardness, pH, and temperature. The toxicity of the water was determined by bioassay of fathead minnows (Pimphales promelas Rafinesque).Mortality in the bioassay was most affected by low DO concentrations in the runoff. High concentrations of chlorides, methoxychlor, and endrin were measured at all the sites throughout the course of the study. Season and rainfall amount and frequency were also important factors affecting mortality. Dilution of toxins and nutrients occurred between the first flush runoff and the runoff at the end of storms, sometimes to below U.S. Federal criteria.     

Validation and Assessment of Diffusive Gradients in Thin-Films (DGT) Technique for Measuring Nutrients in Taihu Lake Water with Algae Bloom

DGT (diffusive gradients in thin films) technique has been developed for measuring nitrogen in freshwaters and applied to assess the bioavailability of phosphorus in soils/sediments. These two elements are the main nutrients causing algae bloom, but DGT has never been used in the field water conditions with algae bloom. In our study, a pair of DGT devices were used in comparison with grab sampling to characterize the performance of this technique to measure labile NO₃-N, NH₄-N, and PO₄-P concentrations in algae-cultivated Taihu Lake water. The results showed that DGT measurement was highly affected by algae bloom and the environmental conditions using the current assemblies, especially for NH₄-N measurement. For in situ measurement of nutrients in the real environment, an improvement to the DGT technique is required. The comprehensive assessment of the level of eutrophication needs to consider a variety of environmental factors rather than just the concentration of nutrients.

     

Acute toxicity of ammonia (NH3-N) in sewage effluent to Chironomus riparius: II. Using a generalized linear model

Toxicity of un-ionized ammonia (NH₃-N) to the midge, Chironomus riparius was compared, using laboratory culture (well) water and sewage effluent (0.4 mg/L NH₃-N) in two 96-h, static-renewal toxicity experiments. A generalized linear model was used for data analysis. For the first and second experiments, respectively, LC₅₀ values were 9.4 mg/L (Test 1A) and 6.6 mg/L (Test 2A) for ammonia in well water, and 7.8 mg/L (Test 1B) and 4.1 mg/L (Test 2B) for ammonia in sewage effluent. Slopes of dose-response curves for Tests 1A and 2A were equal, but mortality occurred at lower NH₃-N concentrations in Test 2A (unequal intercepts). Response of C. riparius to NH₃ in effluent was not consistent; dose-response curves for tests 1B and 2B differed in slope and intercept. Nevertheless, C. riparius was more sensitive to ammonia in effluent than in well water in both experiments, indicating a synergistic effect of ammonia in sewage effluent. These results demonstrate the advantages of analyzing the organisms entire range of response, as opposed to generating LC₅₀ values, which represent only one point on the dose-response curve.     

Effects of the source and level of nitrogen on the yield and nutritive value of corchorus olitorius

(1). The effects of two sources and three levels of nitrogen on yeild and nutritive value of Corchorus Olitorius (Tiliaceae) were investigated in the greenhou se. (2). C. olitorius showed greater response to N applied in No₃- form than that applied in NH⁴ form in terms of yield and quality. (3) Higher Ca and Mg content were obtained with No₃-N than NH₄-N. (4) Higher P and K content Were obtained with NH₄-N. (5) Increasing N application also increased ascorbic acid content.     

Physiological Stress of High NH<Stack><Subscript>4</Subscript><Superscript>+</Superscript></Stack> Concentration in Water Column on the Submersed Macrophyte <Emphasis Type="Italic">Vallisneria Natans</Emphasis> L.

The submersed macrophyte, Vallisneria natans L., was cultured in laboratory with NH₄⁺-enriched tap water (1 mg L⁻¹ NH₄-N) for 2 months and the stressful effects of high ammonium (NH₄⁺) concentrations in the water column on this species was evaluated. The plant growth was severely inhibited by the NH₄⁺ supplement in the water column. The plant carbon and nitrogen metabolisms were disturbed by the NH₄⁺ supplement as indicated by the accumulation of free amino acids and the depletion of soluble carbohydrates in the plant tissues. The results suggested that high NH₄⁺ concentrations in the water column may hamper the restoration of submersed vegetation in eutrophic lakes.     

Fate of Potential Contaminants Due to Disposal of Olive Mill Wastewaters in Unprotected Evaporation Ponds

The disposal of olive mill wastewaters (OMW) in shallow and unprotected evaporation ponds is a common, low-cost management practice, followed in Mediterranean countries. So far, the fate of potential soil pollutants in areas located near evaporation ponds is not adequately documented. This study investigates the extent in which the long-term disposal of OMW in evaporation ponds can affect the soil properties of the area located outside the evaporation pond and assesses the fate of the pollution loads of OMW. Four soil profiles situated outside and around the down slope side of the disposal area were excavated. The results showed considerable changes in concentration of soil phenols at the down-site soil profiles, due to the subsurface transport of the OMW. In addition, excessive concentrations of NH₄ ⁺, PO₄ ^3? and phenols were recorded in liquid samples taken from inside at the bottom of the soil profiles. It is concluded that unprotected evaporation ponds located in light texture soils pose a serious threat to favour soil and water pollution.     

Nitrogen, phosphorous, and organic carbon removal in simulated wetland treatment systems

Effects of vegetation, wastewater drawdown, hydraulic retention time (HRT), and media depth on removal of nitrogen, phosphorous, and organic carbon in microcosms were investigated. Synthetic wastewater was added daily to 28 microcosms, and effluent was sampled every 12 days for 132 days. Effluent was analyzed for ammonium (NH₄ ⁺-N), nitrate (NO₃ ⁻-N), orthophosphate (PO₄ ³⁻-P), and total organic carbon (TOC). Average percent removal of NH₄ ⁺-N was significantly greater in microcosms containing plants (67%) than in those without plants (29%). Percent removal of PO₄ ³⁻-P was also significantly greater in microcosms with plants (42%) than in microcosms without plants (20%), but no significant difference was found for TOC removal between microcosms with plants (67%) and those without plants (74%). Average removal was significantly lower in microcosms with wastewater drawdown than in those without wastewater fluctuation for both NH₄ ⁺-N (51% versus 83%) and PO₄ ³⁻-P (14% versus 71%). Percent NH₄ ⁺-N removal was significantly greater in microcosms with a 6-day retention time (80%) than in those with a 2-day retention (53%), and PO₄ ³⁻-P removal was also significantly greater with a 6-day retention time (55%) than a 2-day retention (29%). No differences were seen in TOC removal due to any of the treatments but HRT, where removal was greater microcosms with a 2-day HRT (76%) than in those with a 6-day HRT (60%). Media depth did not have a significant effect on nutrient removal. Results of this study demonstrate that required design parameters are different depending on the nutrient being removed in systems simulated by these microcosms. Received: 15 August 2000/Accepted: 3 April 2001     

Chronic Toxicity of Ammonia to the Freshwater Bivalve Sphaerium novaezelandiae

The chronic toxicity of total ammonium and unionized ammonia (NH₃) to the native New Zealand freshwater fingernail clam Sphaerium novaezelandiae was assessed in soft water under laboratory conditions. Control survival after 60 days was high (93%) and concentration-response relationships showed the sensitivity of S. novaezelandiae survival was markedly greater to both total and unionized ammonia (6.4× and 4.6×) after 60 days compared with the 30-day exposure at 20°C. Chronic mortality and number moribund (inability to rebury) showed similar sensitivities, but reproduction was a more sensitive endpoint based on a concentration-response analysis. The survival LC50 values for total and unionized ammonia were 3.8 mg (N)/L (pH 7.5) and 0.037 mg (NH₃-N)/L, and reproductive values 0.80 mg (N)/L (pH 7.5) and 0.013 mg (NH₃-N)/L at 60 days. No observed effect concentration (NOEC) values for both survival and reproduction were 0.97 mg (N)/L and 0.011 mg (NH₃-N)/L, and the lowest observed effect concentration (LOEC) values were 5.4 mg (N)/L and 0.046 mg (NH₃-N)/L for survival after 60 days, giving a calculated threshold effect concentration (TEC) of 2.3 mg (N)/L and 0.022 mg (NH₃-N)/L. Comparison of the S. novaezelandiae chronic ammonia sensitivity data with the US EPA criteria showed the survival and reproduction TEC values for total ammonia were 1.9× higher than the chronic criterion, and the lethality value 1.4× above the unionized ammonia criterion. The findings suggest that use of the US EPA criteria would provide minimal protection for S. novaezelandiae for chronic ammonia exposure, and that development of site-specific criteria, covering a wide range of environmental conditions, may be required to adequately protect all life stages of this species. Received: 23 September 1996/Accepted: 27 July 1998     

Associations between daily mortalities from respiratory and cardiovascular diseases and air pollution in Hong Kong, China

Objective: To investigate the association between ambient concentrations of air pollutants and respiratory and cardiovascular mortalities in Hong Kong.

Methods: Retrospective ecological study. A Poisson regression of concentrations of daily air pollutants on daily mortalities for respiratory and cardiovascular diseases in Hong Kong from 1995 to the end of 1998 was performed using the air pollution and health: the European approach (APHEA) protocol. The effects of time trend, seasonal variations, temperature, and humidity were adjusted. Autocorrelation and overdispersion were corrected. Daily concentrations of nitrogen dioxide (NO₂), sulphur dioxide (SO₂), ozone (O₃), and particulate matter <10 µm in aerodynamic diameter (PM₁₀) were averaged from eight monitoring stations in Hong Kong. Relative risks (RRs) of respiratory and cardiovascular mortalities (per 10 µg/m³ increase in air pollutant concentration) were calculated.

Results: Significant associations were found between mortalities for all respiratory diseases and ischaemic heart diseases (IHD) and the concentrations of all pollutants when analysed singly. The RRs for all respiratory mortalities (for a 10 µg/m³ increase in the concentration of a pollutant) ranged from 1.008 (for PM₁₀) to 1.015 (for SO₂) and were higher for chronic obstructive pulmonary diseases (COPD) with all pollutants except SO₂, ranging from 1.017 (for PM₁₀) to 1.034 (for O₃). RRs for IHD ranged from 1.009 (for O₃) to 1.028 (for SO₂). In a multipollutant model, O₃ and SO₂ were significantly associated with all respiratory mortalities, whereas NO₂ was associated with mortality from IHD. No interactions were detected between any of the pollutants or with the winter season. A dose-response effect was evident for all air pollutants. Harvesting was not found in the short term.

Conclusions: Mortality risks were detected at current ambient concentrations of air pollutants. The associations with the particulates and some gaseous pollutants when analysed singly were consistent with many reported in temperate countries. PM₁₀ was not associated with respiratory or cardiovascular mortalities in multipollutant analyses.

     

Effect of Early Life Exposure to Air Pollution on Development of Childhood Asthma

Background

There is increasing recognition of the importance of early environmental exposures in the development of childhood asthma. Outdoor air pollution is a recognized asthma trigger, but it is unclear whether exposure influences incident disease. We investigated the effect of exposure to ambient air pollution in utero and during the first year of life on risk of subsequent asthma diagnosis in a population-based nested case–control study.

Methods

We assessed all children born in southwestern British Columbia in 1999 and 2000 (n = 37,401) for incidence of asthma diagnosis up to 3–4 years of age using outpatient and hospitalization records. Asthma cases were age- and sex-matched to five randomly chosen controls from the eligible cohort. We estimated each individual’s exposure to ambient air pollution for the gestational period and first year of life using high-resolution pollution surfaces derived from regulatory monitoring data as well as land use regression models adjusted for temporal variation. We used logistic regression analyses to estimate effects of carbon monoxide, nitric oxide, nitrogen dioxide, particulate matter ≤ 10 μm and ≤ 2.5 μm in aerodynamic diameter (PM₁₀ and PM_2.5), ozone, sulfur dioxide, black carbon, woodsmoke, and proximity to roads and point sources on asthma diagnosis.

Results

A total of 3,482 children (9%) were classified as asthma cases. We observed a statistically significantly increased risk of asthma diagnosis with increased early life exposure to CO, NO, NO₂, PM₁₀, SO₂, and black carbon and proximity to point sources. Traffic-related pollutants were associated with the highest risks: adjusted odds ratio = 1.08 (95% confidence interval, 1.04–1.12) for a 10-μg/m³ increase of NO, 1.12 (1.07–1.17) for a 10-μg/m³ increase in NO₂, and 1.10 (1.06–1.13) for a 100-μg/m³ increase in CO. These data support the hypothesis that early childhood exposure to air pollutants plays a role in development of asthma.     

Respiratory effects of sulphur dioxide: a hierarchical multicity analysis in the APHEA 2 study

Aims: To assess the association between daily levels of SO₂ and daily levels of respiratory admissions in a larger and more recent study.

Methods: Time series of daily counts of hospital emergency admissions were constructed for asthma at ages 0–14 years and 15–64 years, COPD and asthma, and all respiratory admissions at ages 65+ years in the cities of Birmingham, London, Milan, Paris, Rome, Stockholm, and in the Netherlands for periods of varying duration between the years 1988 and 1997. A two stage hierarchical modelling approach was used. In the first stage generalised additive Poisson regression models were fitted in each city controlling for weather and season. These results were then combined across cities in a second stage ecological regression that looked at potential effect modifiers.

Results: For an increase of 10 µg/m³ of SO₂ the daily number of admissions for asthma in children increased 1.3% (95% CI 0.4% to 2.2%). Effect modification among cities by levels of other air pollutants or temperature was not found. The SO₂ effect disappeared after controlling for PM₁₀ or CO, but correlation among these pollutants was very high. Other respiratory admissions were not associated with SO₂.

Conclusion: SO₂ is associated with asthma admissions in children, indicating that reduction in current air pollution levels could lead to a decrease in the number of asthma admissions in children in Europe.

     

Monitoring Water Pollution Levels in Wadi Hanifa,Riyadh, Saudi Arabia and its Public Health Implications

This study was performed to evaluate the levels of metals in the fish caught from Wadi Hanifa’s main basin over four seasons, determine the potential fitness of the fish for human consumption, and evaluate the overall water quality after enforcement of local standards. The physical and chemical parameters from a total of 192 water samples were tested using standard methods. Additionally, a total of 48 fish samples were analyzed for heavy metal concentrations. Mean values for basic water quality parameters of COD, PO₄ ^?3, NH₃ ^?-N, and NO₃ ^?-N exceeded Saudi standards in all seasons. Mean metal concentrations in water were consistently at their highest concentrations in samples collected during the summer, and the lowest in samples collected during the winter. Mean metal concentrations in fish muscle tissue exceeded Saudi standards for As and Cd, and United Nations FAO standards for Cr, Ni, Zn, Fe and Mn. Statistical analysis showed highly significant positive correlations between metal concentrations in water and metal concentrations in fish muscle for As–Fe, Pb–Cr, Pb–Ni, Cr–Cu, and Cu–Fe. This study highlights the urgent need for monitoring and controlling wastewater discharge in Wadi Hanifa to ensure public safety.     

Spatio-seasonal variation in ambient air pollutants and influence of meteorological factors in Coimbatore,Southern India

Air quality is used worldwide to confirm the current status of air pollution level and associated health risks to the public. Several air pollutants reach very high concentrations in many regions across India. In this study, air pollutants were measured in an urban city of Coimbatore, Tamil Nadu, Southern India, during 2013 to 2014 based on season and location, and the influence of meteorological factors. Air pollutants (PM₁₀, PM_2.5, SO₂, NO₂, CO, and O₃) across eight locations including industrial, residential, traffic, and commercial areas were assessed. The results showed that PM₁₀, PM_2.5, and CO were the most serious pollutants and their average concentrations ranged from 65.5 to 98.6 μg/m³, 27.6 to 56.9 μg/m³, and 1.58 to 8.21 mg/m³, respectively, among various locations. Significantly higher concentration of air pollutants was recorded in industrial areas followed by traffic and commercial areas. Comparatively higher mean concentration of O₃ (2.22?±?0.75 μg/m³) and CO (7.73?±?1.86 mg/m³) was recorded during the summer season, whereas the concentration of PM₁₀ (80.3?±?24.4 μg/m³), PM_2.5 (45.1?±?17.7 μg/m³), SO₂ (7.86?±?1.55 μg/m³), and NO₂ (13?±?1.81 μg/m³) was higher in southwest monsoon. Ozone (O₃) and CO positively correlated with temperature and negatively correlated with relative humidity. The level of PM₁₀, PM_2.5, and CO concentrations exceeded the National Ambient Air Quality Standards (NAAQS) guidelines. The present study’s results emphasize the need of effective air pollution control in Coimbatore. Precautionary measures to be taken to avoid exposure of air pollutants to the public and minimize pollutants. This study further suggests an investigation on the adverse impact on human health and environment using appropriate risk analysis techniques.     

Effectiveness of Vegetated Drainage Ditches for Domestic Sewage Effluent Mitigation

Plant species have an important role in eco-ditches; however, the Michaelis–Menten kinetic parameters of nutrient uptake, growth rate and purification efficiency of ditch plants and their influences on domestic sewage treatment efficiency are still unclear. Growth rates of all nine species, but especially Lemna gibba, Cladophora and Myriophyllum verticillatum were best in undiluted domestic sewage as opposed to a mixture of domestic sewage. Performance of species to accumulate nutrients was not only species-specific, but was also affected by both sewage treatments. Removal efficiency of nutrients was dependent on both plant species and treatment. Uptake kinetic parameters were significantly affected by both nutrient form and plant species. The maximum uptake rate (Vmax) of NH₄-N was higher than NO₃-N. Similarly, Km values for NH₄-N were greater than NO₃-N. These results could be used to identify plants for sewage treatment efficiency and enhance water quality in eco-ditch treatment systems.     

Does calcium in drinking water modify the association between nitrate in drinking water and risk of death from colon cancer?

The objective of this study was to explore whether calcium (Ca) levels in drinking water modified the effects of nitrate on colon cancer risk. A matched case–control study was used to investigate the relationship between the risk of death from colon cancer and exposure to nitrate in drinking water in Taiwan. All colon cancer deaths of Taiwan residents from 2003 through 2007 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by gender, year of birth and year of death. Information on the levels of nitrate-nitrogen (NO₃-N) and Ca in drinking water have been collected from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cases and controls was assumed to be the source of the subject's NO₃-N and Ca exposure via drinking water. We observed evidence of an interaction between drinking water NO₃-N and Ca intake via drinking water. This is the first study to report effect modification by Ca intake from drinking water on the association between NO₃-N exposure and risk of colon cancer mortality.     

Traffic related air pollution and acute hospital admission for respiratory diseases in Drammen, Norway 1995–2000

The aim of this study was to estimate the associations between seven ambient air pollutants [particulate matter (PM₁₀), nitrous dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), benzene, formaldehyde and toluene] and acute hospital admissions for respiratory diseases in Drammen, Norway 1995–2000. Time-series analysis of counts was performed by means of generalized additive models with log link and Poisson distribution. The results showed that benzene was the pollutant having the strongest association with respiratory diseases for the total study period, the relative risk of an interquartile increase of benzene was 1.095 with 95% confidence interval: 1.031–1.163. The corresponding results were 1.049 (0.990–1.112) for formaldehyde, 1.044 (1.000–1.090) for toluene, 1.064 (1.019–1.111) for NO₂, 1.043 (1.011–1.075) for SO₂, 0.990 (0.936–1.049) for O₃ and 1.022 (0.990–1.055) for PM₁₀. Dividing the total study period into two 3-year periods, there was a substantial reduction in the exposure levels of the volatile organic compounds (benzene, formaldehyde and toluene) from the first to the second period. Separate analyses for the second time period showed weaker association between these pollutants and the health outcome. This study provides further evidence for short-term respiratory health effects of traffic related air pollution.     

Chemical characteristics and possible causes of acid rain at a regional atmospheric background site in eastern China

A total of 43 rainwater samples were collected from March 2014 to February 2015 at a regional atmospheric background station, in Lin’an, Zhejiang province, eastern China. We analyzed all rainwater samples for pH, electrical conductivity, and concentration of SO₄ ^2?, NO₃ ^?, Cl^?, F, NH₄ ⁺, Ca²⁺, Na⁺, Mg²⁺, and K⁺. The pH of the 43 analyzed rainfall events ranged from 3.39–6.37, with a volume-weighted mean (VWM) of 4.74; 72% of the precipitation events qualified as acid rainfall (those where the rain pH was <5.6), indicating that acid rain pollution was severe in Lin’an area. Although the ionic concentrations in the Lin’an rainwater were lower than those found in most urban areas in China and in rural areas in India, they were still higher than those in Waliguan (a global atmospheric background station in northwestern China) and in Newark, NJ, USA. We found that SO₄ ^2? and NO₃ ^? were the major anions in the precipitation, accounting for an average of 88% of the total inorganic anions. The SO₄ ^2? concentration was between 3.8–303.9 μeq L^?1 with a VWM value of 49.8 μeq L^?1, while the NO₃ ^? concentration was between 3.0–206.5 μeq L^?1 with a VWM value of 32.6 μeq L^?1. The ratios of SO₄ ^2? to NO₃ ^? ranged from 0.71 to 2.56 with an average of 1.53, indicating that SO₄ ^2? was the most significant anion causing rainfall acidification in Lin’an area. This is similar to observations made in 2008. Compared to observations in Lin’an area in 2008, the contribution of SO₄ ^2? to rainwater acidity had decreased due to sharp reduction in SO₂ emissions, while the contribution of NO₃ ^? had increased due to a rapid growth in the use of motor vehicles in eastern China. We observed that the alkaline component NH₄ ⁺ made the largest contribution toward neutralizing rainwater acidity. The neutralization factor (NF) for NH₄ ⁺ was between 0.26 and 1.03 with an average of 0.63, and the NF for Ca²⁺ was between 0.09 and 1.21 with an average of 0.30. The ratio of Ca²⁺ to NH₄ ⁺ was between 0.15 and 4.70 with an average of 0.48, lower than that observed in Chinese urban areas and close to that observed in non-urban Chinese sites. These results indicated that Ca²⁺ was still a major factor in buffering rainwater acidity in most urban areas in China, while NH₄ ⁺ seemed to be the most important basic ion for neutralizing rainwater acidity in non-urban areas. In the Lin’an area, the Cl^? and K⁺ in rainwater were mostly of marine origin; however, SO₄ ^2?, Ca²⁺ and Mg²⁺ were generated mainly from the earth’s crust and anthropogenic emissions.     

The association of air pollution with congenital anomalies: An exploratory study in the northern Netherlands

Background

There are a growing number of reports on the association between air pollution and the risk of congenital anomalies. However, the results are inconsistent and most studies have only focused on the association of air pollution with congenital heart defects and orofacial clefts.

Short-term association between exposure to ozone and mortality in Oporto, Portugal

Exposures to air pollution in developed countries have generally decreased over the last two decades. However, many recent epidemiological studies have consistently shown positive associations between low-level exposure to air pollutants and health outcomes. In Portugal, very few studies have analysed the acute effect of air pollutants on health.The present study evaluates the association between exposure to air pollution and daily mortality in the Oporto Metropolitan Area, Portugal. Generalised additive models were used for this analysis. Pollutants assessed were ozone, nitrogen dioxide, and particulate matter (PM₁₀). Models were adjusted for time trend, seasonality, and weather.We report that an increase of 10 μg/m³ in the daily ozone 8-h maximum moving-average corresponds to an increase of 0.95% (95%CI: 0.30, 1.60) and 1.58% (95%CI: 0.45, 2.73) in non-accidental mortality and cardiovascular mortality, respectively, in the summer season. A significant effect of 0.67% (95% CI: 0.03:1.32) was also found for the association between PM₁₀ and non-accidental mortality in the summer season. Associations with ozone and PM₁₀ exposures were higher in the elderly people. No significant effects on mortality were observed during the summer season with nitrogen dioxide exposures.Our analyses provide the first significant evidence in Oporto that exposures to O₃ and PM₁₀ have adverse effects on the health of the general population in the summer months.