Climate Change and Health Seminar Series: “Air pollution health effects under climate change: a complex interaction with various pathways”

November 15, 2022

Information

Dr. Evi Samoli joined the Center on Climate Change and Health to discuss her work on air pollution and climate change.

Speaker:

Evi Samoli, Associate Professor of Epidemiology and Medical Statistics; Medical School of the National and Kapodistrian University of Athens (NKUA), Greece

October 10, 2022

ID9110

To CiteDCA Citation Guide

00:00<v Professor Chen>We're ready.</v>
00:01So let's get (indistinct), everybody.
00:04Thanks everyone, for (indistinct).
00:07It's our second (indistinct) series on (indistinct) today,
00:13and I'm very pleased today
00:17to be able to invite Dr. Evi Samoli for today's seminar.
00:22Dr. Samoli is Associate Professor
00:25of Epidemiology and Medical Statistics
00:28in the Medical School of the National and Kapodistrian,
00:32University of Athens in Greece.
00:35And Dr. Samoli's research interests
00:38focus on environmental epidemiology,
00:40especially the health effects
00:42of air pollution and climate change,
00:44and the development and application
00:47of statistical methods in related research.
00:50She has organized and participated
00:52in several statistical workshops
00:54and Greek and international conferences.
00:59She has been a reviewer
01:00and also a research committee member
01:02of the US Health Effects Institute,
01:05and also as for the WHO.
01:10She recently co-chaired this year's international conference
01:16for the International Society of Environmental Epidemiology.
01:21And her talk today will be
01:22Air Pollution Health Effects Under Climate Change:
01:25A Complex Interaction with Various Pathways.
01:29So without further ado, (indistinct).
01:33<v ->Thank you very much for the introduction, Professor Chen.</v>
01:37It's my pleasure to share some of the results
01:41with you and your class,
01:43and I would like to personally thank you
01:44for the invitation for this talk.
01:47Because I understand it's a rather diverse audience,
01:52I will focus my first slides
01:54on introducing the concept of air pollution,
01:57because as Professor Chen mentioned,
02:01my focus is on ambient air pollution,
02:04and what we know now of the health effects of air pollution,
02:07and then go deeper into how this interacts
02:10with the climate change health effects.
02:14Now to start with, the pollutant that we know
02:17has most effects on health is particulate matter
02:21with an aerodynamic diameter of 2.5 micrometers.
02:26To get you an idea of what particular matter PM 2.5 means,
02:31it's matter that is airborne in the air,
02:36and with small, so small as you can see from the graph here,
02:41that's smaller in fact than a red blood cell.
02:45So initially, we had investigated particulate matter
02:49that had a diameter of 10 micrometers, so was PM 10.
02:53But the most toxic effects of particulate matter
02:56are those associated with the smaller particles
02:59which are easier to penetrate into the lung
03:02from the respiratory tract
03:04and cause (indistinct) stress and inflammation.
03:08Now you must consider that
03:09because particulate matter is matter that is airborne,
03:14its composition changes according to its sources,
03:19and it also attracts different kind of chemical compounds
03:24depending on the atmosphere.
03:26So we have particles that are directly emitted from sources
03:30such as tailpipe exhaustion sources,
03:35or we have secondary particles formed in the atmosphere
03:38through chemical reactions.
03:41In this part of the slide,
03:43you can see the different figures,
03:47the different pictures of particulate matter
03:49that has different compositions.
03:51So for example, this is a biological source
03:55of particulate matter.
03:57The one next to it, I'm not sure if you can see my cursor,
04:01is my cursor visible while...
04:03<v ->Yes, we can see.</v> <v ->Excellent.</v>
04:05So this one is particulate matter
04:07that is emitted from tailpipes.
04:10It's soot particulate matter.
04:12This is from an unknown source, and this basically is dust.
04:19So not only the size of particulate matter differs,
04:23but also the composition differs according to sources.
04:26Of course, when we talk about ambient air pollution,
04:30apart from ambient particulate matter,
04:32we are exposed to a variety of gasses,
04:35of which the most common are nitrogen oxides
04:40and sulfur dioxide, carbon monoxide,
04:45and several hydrocarbons.
04:47Here in this slide,
04:49you can see the sources of particulate matter
04:52or gaseous pollutants from research in the UK,
04:57because you must understand
04:59that the main sources will differ
05:02according to the location, because the sources will differ.
05:06But in general,
05:07nitrogen oxides are mainly emitted from traffic,
05:11traffic related pollutants,
05:13and are emitted from tailpipe emissions,
05:17while particulate matter, depends on the sources,
05:20comes heavily from residential
05:22and small scale commercial combustion, as you see here.
05:26But also, it may be emitted from tailpipe,
05:29or non tailpipe sources, for example,
05:32they might be dust particles in the air
05:35that come also from the brakes
05:38and the tire contact of the car into the roads.
05:46From the gaseous pollutants,
05:47the one that has received most attention
05:49apart from nitrogen oxide,
05:51and the one that is most relevant
05:53with climate change is ozone.
05:56So you may be aware that ozone
05:59is in different strata of the atmosphere.
06:02When ozone is on the external atmosphere,
06:05what that is called the stratosphere,
06:07is the ozone that it's good for the environment,
06:10that protects, in fact,
06:12Earth from the sun's ultraviolet radiation.
06:15But when we talk about ozone in air pollution,
06:19we mean the ozone that is encountered in the troposphere,
06:24in the lower levels of the atmosphere.
06:27And this, in fact, is a secondary gaseous pollutant,
06:31because in order to form ozone in the troposphere,
06:36this is formed from secondary chemical reactions
06:39that require nitrogen oxides emitted from traffic sources
06:45in the presence of sunlight.
06:48That is why it is heavily dependent
06:50on climate change scenario,
06:52because as we expect that the heat will increase,
06:55the temperature will heat because of climate change,
06:59ozone levels are also expected to increase,
07:03and I will give a small presentation
07:05about the known health effects of these air pollutants.
07:10Now in general, air pollution health effects
07:12are very small, (indistinct) made very small relative risks
07:16compared to other risk factors for health.
07:19For example, we might estimate relative risks
07:24of the scale of 1.06.
07:28So it's a very small relative risk for human health,
07:31but if we consider the involuntary exposure
07:36of the whole population to air pollution,
07:39we understand why this is considered
07:42a major risk factor for human health.
07:46And this translates also to a large number
07:50of attributable deaths.
07:52So in general, in this pyramid,
07:54it's a classic pyramid portraying
07:56the effects of air pollution,
07:58where the majority of the population
08:00is in the bottom of the pyramid,
08:02and is expected to have only very minor symptoms.
08:08But as we go up to the pyramid,
08:12the severity of the effect increases,
08:16and the proportion of the population
08:18that is expected to experience
08:20these severe health effects is reduced.
08:23But nevertheless, because exactly the exposure is so wide,
08:28this is a considerable number of attributable cases,
08:32and that is why it's a very critical matter
08:35for public health.
08:38How do we estimate the health effects of air pollution?
08:42There are two kinds of ways to approach and investigate
08:45health effects of air pollution.
08:47One is short term health effects,
08:49meaning the health effects that are encountered
08:52after a few days, or at most,
08:56a month prior to the event that we're interested in.
09:00Or the long term health effects,
09:02meaning that the health effects that are attributed
09:06to cumulative exposure to air pollution, for example,
09:09to air pollution we're exposed to at our residence.
09:14And this may help, as it has been shown
09:18to increase the incidence of cancers,
09:21and particularly lung cancer.
09:23So there's those two ways of effects,
09:27either short or long-term effects.
09:29But nevertheless, as you may imagine,
09:32there's a continuing, continuing, excuse me,
09:35between short and long term health effects,
09:38that it's not completely understood.
09:42Short term health effects are very smaller
09:44compared to magnitude,
09:46compared to longer term health effects in general.
09:51You may be aware of the Global Burden of Disease project,
09:55that classifies risk factor for health globally
10:00in a periodic time periods.
10:03Air pollution is always classified
10:06on the 10 most important risk factors
10:09for health globally,
10:11either if this is accounted for in number of deaths,
10:16or disability adjusted years.
10:18In the latest classification
10:20of the Global Burden of Disease project,
10:23you may see that air pollution in terms of mortality
10:27was classified as the fourth risk factor,
10:30only below high blood pressure, smoking habits,
10:34and dietary habits as well.
10:38And it accounted for about
10:406.7 million deaths annually globally.
10:44Now these kinds of health effects are attributed,
10:47and this is what is estimated underneath these figures.
10:51These are health effects attributed to PM 2.5,
10:56as I introduced it earlier, and to ozone health effects.
11:00These are the two pollutants
11:02that we have the most consistent evidence on health effects.
11:07For PM 2.5, basically,
11:12this accounts for long term health effects,
11:15while for ozone, we are most certain
11:20about its short term lung effects,
11:22while the longer term health effects of ozone exposure
11:26are still under investigation.
11:29What kind of disease we are talking about
11:32when we are talking about air pollution health effects?
11:36You can see here from the State of Global Air,
11:39that I urge you to visit, is a site
11:42that it's been sustained by the Health Effects Institute,
11:45and has similar figures
11:48of the levels of air pollution globally,
11:50or the attributable number of deaths
11:53attributable to PM 2.5 exposure,
11:56ozone exposure, or even household indoors exposure.
12:01So we can see that we have about 40% of COPD deaths
12:09attributed to PM 2.5.
12:1220% about from diabetes deaths
12:16are attributed to air pollution.
12:1820% of ischemic heart disease,
12:20or lower respiratory infections.
12:23About 20% of lung cancer cases are also attributed
12:27to ambient air pollution, and also to neonatal deaths,
12:33it's a similar percentage, or stroke.
12:38Following these severe health effects
12:39for the general population
12:41and the importance in public health.
12:44WHO releases air quality guidelines regularly,
12:49and in the last month,
12:51it has released the more strict guidelines,
12:57requiring air pollutant levels for PM 2.5
13:02to be less than five micrograms per cubic meter.
13:05This is a mean year average.
13:09PM 10 is a bit higher, it's 15 micrograms,
13:13the limit suggested.
13:14For ozone, you can see it's 60 micrograms per cubic meter.
13:19Ozone usually is measured in the US in parts per billion.
13:23So you may see the units in PPB.
13:27And the nitrogen dioxide is about
13:3010 micrograms per cubic meter as a annual average.
13:3524 daily averages are always a bit larger.
13:43Now how do this compare to the existing levels
13:47of air pollutants?
13:48I may assure you that both for US
13:51and the large majority of European countries,
13:56these are lower than the existing levels of air pollution,
14:01considering the year averages.
14:04The WHO air guidelines
14:07are not legislative binding for the countries.
14:13They're based on protecting public health,
14:16and then the area specific authorities
14:22release their own guidelines,
14:24taking into account not only the interest of public health
14:29and how this is reflected in the WHO guidelines,
14:32but also, as you may imagine, other aspects
14:35such as the cost benefit fractions,
14:38and how would this impact the economy
14:42in order to lower the levels in terms of productivity,
14:45industry, and so on, and so on.
14:48So here, in this slide, you will see the limit values
14:53that are currently existing,
14:57both in the European Commission on the left,
15:00and UN's on the right that you can see.
15:04The levels are higher than those
15:07that are proposed by the WHO.
15:10For example, for PM 2.5, you can see here,
15:14depending on the source, that EPA suggested limit values
15:19are very much higher
15:21than the five micrograms per cubic meter
15:24proposed by WHO, while for the same pollutant and metric
15:33in Europe, we have even larger limit values.
15:37These are the legislative binding limit values
15:41for the state members.
15:42So in Europe, for example, if we exceed this kind of limit,
15:47we are under fine to the European Commission.
15:53And nevertheless, it's clear that this is not a measure
15:57that protects public health,
15:58and it's a big pressure nowadays to lower the limits,
16:02both in US and the European Union.
16:06So coming into the interplay
16:08with climate change health effects.
16:11We know that the climate change health effects
16:15can be either direct or indirect.
16:18For example, we have direct health effects
16:21due to climate change extreme events,
16:23such as heat strokes under heat waves,
16:27or we may have fatalities in wildfires
16:32and similar extreme events.
16:34But we also have indirect health effects
16:36attributed to climate change,
16:39because climate change impacts also
16:42the quality of the air,
16:45so it worsens the levels of air pollutants.
16:48Hence, we have this indirect effect
16:52from increasing the health effects of air pollution
16:56that I mentioned earlier.
16:59I will show in the later slides
17:02that this is a much more complex interaction
17:06between climate change events and air pollutants.
17:09It also has indirect health effects,
17:12because climate change impacts also public health services.
17:18So the public health sector is not ready
17:22to accommodate the extra events
17:25attributed to climate change extreme events,
17:27but also to the entire effect that follow
17:31climate change events.
17:34This comes from a report in the European Commission
17:38that somehow schematically illustrates what you may know,
17:42that temperature has effects on human health.
17:45We know that, for example,
17:48mortality occurs in low temperatures or in high temperature.
17:52The shape between temperature levels and health
17:56is a parabola, a U shape,
17:59where we see increasing events in the very low temperatures,
18:02as you may imagine, or the very high temperatures.
18:05So temperature has a direct effect on human health.
18:10And in fact, the temperature effects on health
18:14are more strong in magnitude
18:16than the effects of air pollution that I mentioned earlier.
18:21As you may see from the report of the European Commission,
18:25there's a geographical variability
18:28in the health effects of temperature,
18:31and generally of climate change.
18:34We have more severe effects in hotter climates,
18:38such as the southern Europe
18:41compared to the northern European countries.
18:43And we have also, not only geographical probability,
18:46but we have a (indistinct) effect
18:48depending on the subpopulation groups we are interested in.
18:52So people that are usually more sensitive
18:57to meteorological and air pollution health effects
19:00are children, pregnant women,
19:03and elderly citizens, or people with preexisting diseases.
19:12Why now climate change has a more complex pathway
19:18to health through air pollution?
19:20Because air pollution emissions also are a contributor
19:26to climate change events.
19:30So emissions increase temperature,
19:34that constitutes part of climate change,
19:37and this, in fact, the increase in temperature,
19:40as I mentioned in the beginning of the talk,
19:43is necessary to produce more ozone,
19:45that is also known to have adverse health effects
19:49to human health.
19:51There are also interactions
19:53between temperature and air pollution,
19:55meaning that we have higher effects of temperature
19:58in more polluted areas,
20:00or we have higher effects of air pollution in warmer areas.
20:05This still now have traditionally been studied separately,
20:09but because of the complex interplay between climate change,
20:14and particularly temperature levels and air pollution,
20:18in the recent years,
20:20this have received increasing attention,
20:23and more publications are coming up,
20:25and I will just go through some main publications
20:28on the topic in the later slides.
20:32Apart from this interplay
20:35between temperature and air pollution,
20:39we know that climate change
20:41increases the occurrence of wildfires.
20:45Wildfires are a main source of emission
20:48of particulate matter in the air.
20:51For example, you may recall
20:52the very intense wildfires that burnt over California,
20:57I think this was two years ago.
20:59The smoke reached all the way
21:02up to the east coast of the US.
21:04So we have the source of wildfires
21:07that not only impacts the location where wildfire occurs,
21:11but also depending on the wind direction and the atmosphere,
21:16atmospheric reaction, may also impact air quality levels
21:21in further distances.
21:25Further up to that,
21:27climate change is expected to increase drought,
21:31and also the frequency of desert dust episodes.
21:35I told you in the beginning
21:37that one source of particulate matter
21:39in ambient air is dust.
21:41So we have occurrences of desert dust transport,
21:44for example, in Greece, and in the southern of Europe,
21:48we have desert dust transport,
21:51traditionally during spring or early summer,
21:54from the Sahara area.
21:56Depending on meteorological conditions,
21:59Sahara area has been shown
22:01also to reach the east coast of US sometimes.
22:03So these kinds of desert dust episodes
22:06are expected to increase both in frequency and duration.
22:12Apart from that, also the fact that climate change
22:16increases drought,
22:18we can understand that this also will increase
22:21suspended particles from dust sources.
22:28This publication is a nice figure,
22:32also graphically showing this direct and indirect effects
22:37between climate change and, in fact,
22:40the focus of this publication was cardiovascular mortality,
22:46because you may know that cardiovascular mortality
22:50typically consists about 30 to 40% of total mortality.
22:56So we can see that from climate change
23:00can have a direct effect to cardiovascular...
23:03Climate change leads to extreme temperature.
23:07Extreme temperature may cause cardiovascular inflammation,
23:12that will lead to cardiovascular mortality
23:16through direct effect,
23:18but also through increases in the ozone levels,
23:22that we know has impacts on cardiovascular mortality,
23:26has an indirect weight towards there.
23:30As mentioned earlier, also,
23:32the wildfires will increase due to climate change,
23:36and wildfires basically are causing increases
23:42in the levels of nitrogen dioxide and particulate matter,
23:47and in a specific chemical composition of particulate matter
23:52that is black carbon
23:53because when solid fuel produces black carbon,
23:58which is one of the constituents,
24:01possible constituents of ambient particulate matter,
24:04that from research until now
24:06has been shown to be one of the most toxic components
24:10of particulate matter.
24:11So wildfire is expected to affect cardiovascular mortality,
24:17again through the same biological pathway,
24:21either by increasing nitrogen dioxide particulate matter,
24:26and when nitrogen dioxide increases,
24:28because it's a necessary
24:30ingredient for the formation of stratospheric ozone,
24:33also ozone will increase.
24:38This is a very nice graph from a current European project
24:43we are running.
24:45Professor Chen is aware of this,
24:47and this has been a graphical display exactly
24:53of the impact of climate change on air pollution
24:56and related health effects,
24:58in order to communicate this to the general public.
25:03So you can see, again, that the title, I think,
25:06is very good for commercial and scientific reasons.
25:10We breathe climate change.
25:12So the impact on cardiovascular mortality
25:15comes from heat waves,
25:17tropospheric or ground level ozone particulate matter,
25:20wildfires, and then we have the health impacts,
25:24that especially in Europe, it has been estimated
25:28that air pollution may cause up to 800,000 premature deaths.
25:37Oops, I'm sorry.
25:40A few words, what we mean
25:44when we talk about ozone health effects.
25:47This is the results of the global study
25:50on the short term exposure to ozone,
25:53and all cause mortality.
25:56In the figure in the left, you may see the countries
25:59that provided data to the specific study,
26:05and here you can see per country,
26:06the number of cities that contributed to data.
26:10We had 188 cities from US that contributed data.
26:16You can see that US contributes
26:18a lot of ozone and mortality data,
26:20and also a lot of European cities
26:23contributed relevant data,
26:25and we had fewer countries in the Eastern Asia,
26:29a few in Asia and in Africa, and some in Australia.
26:34The figure shows the different levels of ozone,
26:38and here, you can see what the estimates,
26:43the relative risks in total mortality
26:46for a 10 micrograms per cubic meter increase in ozone.
26:51So this is short term health effects of ozone.
26:55It's the previous day ozone,
26:58and how this will increase the next day
27:02total mortality in the cities.
27:04And you can see, for example, that in the United States,
27:08the 10 micrograms increase in ozone
27:11is associated with about 0.2% increase
27:16in daily number of deaths.
27:170.2% increase is a small increase in terms of magnitude.
27:24But when we translate this into number of deaths,
27:28you can see that this is a large number of deaths.
27:32For example, if ozone exceeds the guideline from WHO,
27:39at that point was 100 micrograms per cubic meter in the US,
27:43this was attributed to about 200 annual excess deaths
27:49attributed to ozone short term exposure.
27:52And this, in fact, was a 0.4% increase in total mortality.
27:57So about, rather, a large percent of total mortality
28:05could be attributed to ozone exposure.
28:09You can also see that
28:10depending on the area of the world analyzed,
28:13the magnitude of effects differed.
28:16Okay, for example, in Athens, that's a smaller country,
28:22sorry, smaller city, because we only contributed one city
28:26to the analysis, compared to Los Angeles, for example,
28:31but is the estimate here, we have fewer number of deaths,
28:35because we have a smaller population.
28:40Especially for USA, it has been estimated
28:43that one to four degrees Celsius increase
28:47in mean daily temperature will lead to an increase
28:51of ozone levels by one to five parts per billion.
28:56This is about 10 micrograms per cubic meter increase,
29:01and this is expected to account
29:03for tens of thousands of hospitalizations
29:06and deaths annually by 2030.
29:10It has also been an estimate,
29:14because you may recall that in 2003,
29:17we had a major heat wave in Europe,
29:21when a lot of excess deaths were attributed exactly
29:25to the effect of this heat wave.
29:28There was a recent study indicating
29:30that about half of these effects of these deaths
29:34could be attributed to the ozone exposure
29:37that increased exactly because of this extreme heat days.
29:45This is one of the first studies to address,
29:50is a study by Professor Chen, in fact,
29:52and it's one of the first studies
29:54to simultaneously assess the interaction,
29:57the interplay between temperature levels
30:00and air pollution levels,
30:02and their impact on the daily mortality.
30:04It was an analysis that incorporated data from,
30:10you can see, eight different areas in Europe,
30:14spanning from Finland to Greece.
30:17So we had cities from northern Europe,
30:21central Europe, and southern Europe,
30:24and the table below shows the results,
30:28how the air pollution health effects differ
30:32according to different levels of air pollution.
30:35Just to briefly mention,
30:37we have the previous day ozone health effects,
30:41the previous day PM 10 health effects,
30:44the previous day PM 2.5 health effects,
30:47and PNC are even smaller particles.
30:51It's a metric to study ultra fine particles,
30:55that are particles that have a diameter
30:59even smaller than 0.1 micrometer.
31:06So if you see a bit closer,
31:08the percent increase of mortality
31:11attributed to each pollutant
31:14depending on the levels of temperature,
31:17we can see steadily that there is a trend
31:20that we have higher effects for all air pollution,
31:24for all air pollutants studied
31:26when air temperature levels are higher.
31:30And the same goes for cardiovascular deaths.
31:35Following this study by Professor Chen,
31:38there have been many other studies
31:40following the same rationale,
31:41and investigating this interaction
31:43between temperature and air pollutants.
31:45And this is a nice review of several studies
31:49across the globe that have tried to assess
31:54the interaction between particles and temperature,
31:58and try to estimate future attributable events
32:02depending on emission scenarios,
32:05both for air pollution and future climatic scenarios.
32:11I see that we are running a bit out of time,
32:14so I will go very quickly through this.
32:17We have the slides,
32:19and you can follow up the references if needed,
32:22but depending on the area,
32:25you can see that we have different air pollutants
32:28that have been assessed.
32:30The majority of the studies assess the effects of ozone,
32:34and in all of them that assess the effects of ozone
32:37under different scenarios,
32:39assessed an increase in attributable cases
32:41to ozone exposure.
32:43Attributable cases to particle exposure
32:46depending on emissions of air pollution
32:48and climate change scenarios
32:50differed according to the study.
32:53We had peaks of particulate matter related deaths,
32:57then deaths stabilized,
32:58or depending on the scenario,
33:00this was not such a consistent pattern as was for ozone.
33:05In any case, the authors urge
33:08that future scenarios to try to account
33:11for both changes in emissions,
33:15because we have transitioned, for example,
33:19from solid fuel to the electric fleet for traffic,
33:24but also to different measures
33:26that will account for different emissions
33:30that will change future climate change scenarios
33:34and associated temperature levels.
33:37This is a systematic review and meta-analysis
33:40trying to assess the evidence
33:42on the combined effects between air pollution,
33:45temperature, and pollen exposure.
33:47I will not go very much in depth,
33:49but this table shows a summary of the results
33:55that started all three exposures together,
33:57because climate change impact,
33:59my talk is focused on human health,
34:02but of course, climate change has impact on agriculture,
34:07and this is expected also to increase
34:11certain levels of pollen, that is also, as we know,
34:14associated with respiratory effects.
34:17So the authors only managed to appraise six studies
34:21that assessed the three exposures altogether,
34:24and depending on certain criteria
34:27of consistency of the evidence
34:30of the cumulative effect of these three exposures,
34:33concluded that overall, there was low quality
34:37in the evidence to support interactive effects
34:41of all air pollutants,
34:44but there was some limited evidence for indications
34:47of interaction effects.
34:50They figured that there was a much larger literature
34:55that had assessed both heat effects
34:58and air pollution simultaneously,
35:00and they managed to gather 39 studies
35:04that assess the interactive effects on both.
35:07And the conclusion of this systematical use
35:11is that, in fact, there was a moderate quality of evidence
35:15that those response relationships in a number of studies
35:22was moderate, but there was sufficient evidence
35:26that there was synergistic effects
35:28between heat and air pollution exposures,
35:31specifically for ozone and particulate matter.
35:36This is a nice review on the climate change impact
35:40on human health and agricultural effects, productivity,
35:47and of course, the different impacts are studied
35:50according to different designs,
35:52and you can see that we have mainly, of course,
35:55observational studies assessing the impact
35:59on human health, and mostly,
36:02when we talk about temperature and air pollution,
36:05I forgot to point out we are focusing on short term,
36:09because we know that temperature has a short term
36:12of human health, and in fact,
36:15high warm temperature have a effect on health,
36:19meaning have increasing hospitalizations
36:22due to cardiovascular or respiratory causes,
36:25or increase in cardiorespiratory mortality
36:28that spans from the same day
36:31up to three days later than the events,
36:34while the effect of the cold temperature
36:36is expected to have a much longer impact.
36:40So we may observe hospitalization and mortality counts
36:44associated with cold effects even following
36:48two weeks after the cold effect, the cold level observed.
36:54So in any case, when we talk about interaction
36:58between temperature and air pollution,
37:01we are focusing on short term health effects of both.
37:05And in this review, also, it pointed out several designs,
37:10and how this was studied both on human health
37:12and agricultural impacts,
37:14and there was this nice figure
37:17showing that temperature does modify
37:20air pollution impacts on health
37:22depending on the area, the pollutant studied,
37:27or the methodological parameters studied,
37:31and that contributed to climate change effect,
37:34and also the vice versa,
37:35that air pollution also modified temperature health effects.
37:43I prefer to briefly show you some results.
37:50This is unpublished work, sorry about this.
37:54This is unpublished work for, again, a global study.
37:58You can see that this study includes about 500 cities
38:02spanning across the globe from 32 studies
38:04that contributed data on air pollution and temperature,
38:09and in fact, present results for the interaction effect
38:13between temperature and air pollution levels,
38:16the short term exposures, and the impact on total mortality.
38:21You can see in the graph again
38:22that the majority of the cities contributing data
38:25come from US and Europe,
38:28and the difference at the top
38:30is the different levels of average temperature,
38:33and lower is the different levels of ozone, for example.
38:38To graphically quickly show you the results,
38:41these are the results from North, Central,
38:44and South America.
38:46So we have the PM 2.5,
38:48let's focus on the main central figure.
38:52It's PM 2.5 effects,
38:54or total mortality by levels of pollutant.
38:58So you can see again a steady trend,
39:01both for Canada, for example, and US,
39:04although this may not be statistically different
39:09between them.
39:10As temperature levels increased,
39:12the effect of PM 2.5 on mortality increases.
39:17This is not the pattern that is observed in Mexico
39:20or other areas of Latin America,
39:25but of course, you may consider that the number of cities
39:28contributing data differs by the country shown here.
39:33The same patterns, pretty much,
39:36was observed in the majority of the European cities.
39:40You can see here for PM 2.5 in Northern Europe,
39:44we have increasing terms in Norway,
39:49but not a consistent pattern for other countries.
39:52There was a increasing trend
39:55also for (indistinct) particles, and the levels,
40:00the effect of ozone depending on temperature levels
40:04did not seem to vary in the European cities.
40:11To give you an idea in numbers,
40:14these are the overall global estimates
40:18of the health effects of the pollutants
40:20depending on the level of air pollution.
40:23So globally, we may see increasing effects,
40:26either of PM 10, PM 2.5, or ozone effects
40:31on total mortality.
40:33Of course, because these are global estimates
40:35of the air pollution health effects,
40:38there is large (indistinct) in this kind of meta-analysis.
40:43As I mentioned earlier, indirect pathway
40:45between climate change and air pollution health effects
40:49comes from wildfires,
40:51and here is one study we had been doing
40:56about 20 years ago that studied the impact
40:59of forest fires on mortality,
41:01and how this could be associated from particulate matter.
41:05This is a dot diagram trying to figure out the pathway
41:11that this may have affected health.
41:13So we may have direct effect,
41:16direct death as an effect of forest fire,
41:19or we may have an indirect death
41:22through increases in particulate matter levels,
41:26or even through increases in temperature,
41:28because locally, the temperature levels also increase
41:33due to wildfire.
41:34So this may affect our health outcomes in multiple pathways.
41:40This figure shows the severity and occurrence
41:43of forest fires in the Southern Europe from 2003 to 2011.
41:49Of course, there was variability depending on the country,
41:53but in general, we saw that there was not much difference
42:00on the effects of particles depending on forest fire days
42:05or non forest fire days.
42:09On smoke free days, for example,
42:11there was a 0.5% increase in total mortality,
42:17and on wildfire affected days,
42:20the increase in mortality was almost double,
42:23but it was not statistically significant,
42:26and it was a very wide (indistinct).
42:29But that's why I mentioned that,
42:31although the results may not be
42:33statistically significantly different between them,
42:37because we have much fewer count of wildfire affected days,
42:43we can see that in most of the cases,
42:46the impact is greater in wildfire affected days.
42:51I mentioned briefly
42:52that what solid fuel emits is black carbon,
42:56and I mentioned that black carbon
42:58is one of the most toxic components
43:00of ambient particulate matter.
43:03Black carbon health effects
43:05have been increasingly been studied.
43:07This is again from the same consortium that I showed you
43:11the paper before, from forest fires,
43:13that we assessed the effects of black carbon on mortality.
43:19And we can see that it had high health effects,
43:23either on the same day of exposure,
43:25or up to an average of three days before the events,
43:30both in Athens and Barcelona.
43:32And the effects of black carbon were much higher
43:34than the ones that usually are observed and attributed
43:39to particulate matter.
43:42This is another study on wildfire sourced PM 2.5,
43:49also coming from the same consortium
43:52studying short term health effects
43:55of air pollutants and temperature effects.
43:57And this study focused exactly on the health effects
44:01from PM 2.5 that was emitted from wildfire.
44:06And you can see again, the figure,
44:08the number of city that contributed data, sorry,
44:14and the level of wildfire related PM 2.5 by city.
44:21They assessed the effect of wildfire PM 2.5,
44:26either on the same day, or up to six days before,
44:29or the red...
44:33The red point on the figure on the left
44:35stands for the three days moving average
44:38of the exposure to wildfire related PM 2.5.
44:43So in all cases, we see very high effects
44:47up to three days after the exposure,
44:50or on the average of the same
44:53and two days prior to the event.
44:56Particularly for US, there was a 0.3% increase
45:01in total mortality associated with PM 2.5
45:05that could be attributed to wildfires.
45:09And this was the same percent increase
45:12attributed also for cardiovascular or respiratory mortality.
45:15Again, the magnitude on the effects
45:18depending on the location, as you may expect, differs.
45:24I also mentioned briefly that we expect an increase
45:27in the frequency duration of desert dust episodes,
45:31and we know also that desert dust
45:34may have impacts on health, and here is again a paper
45:41investigating the impact of desert dust
45:47on daily mortality in southern Europe.
45:51And you can see,
45:52because particles from desert dust are of larger diameter,
45:58we assessed here the health effects of PM 10,
46:01that are larger, as I mentioned in the beginning,
46:03compared to PM 2.5, and whether this could be attributed
46:08to non desert dust sources,
46:10or desert sources, excuse me.
46:14So in total, for example, for all cause mortality,
46:18an increase in PM 10 was associated
46:21with a 0.5% increase in total mortality.
46:25This was a bit higher, 0.55, for non desert PM 10,
46:32and PM 10 originating from desert dust
46:38had even higher effect on total mortality,
46:42and pattern was pretty much the same
46:44when we assessed cardiovascular mortality,
46:47respiratory mortality,
46:48and also there was an impact on hospital admissions.
46:53Just to close, and apologies for taking all the time.
46:57We had a major event in Athens last year
47:00that you may not be aware of,
47:03but for our twisted mind as scientists was very intriguing,
47:09because we have a very intense heat wave
47:12that lasted more than three weeks,
47:16and after two weeks of heatwave,
47:18also a major wildfire started
47:22in the northern suburbs of Athens.
47:24So we are in the process of studying this
47:29on mortality in the general population of Athens.
47:32The graph shows the excess number of deaths,
47:36and you can see the counts in daily mean temperature
47:42in the previous years, compared to the period
47:47that the heat wave and the desert
47:49and the wildfire started in Athens,
47:53and also the average number of deaths in previous years,
47:58and the excess numbers of deaths during this episode,
48:01that we can see higher increases, of course,
48:03in temperature and excess deaths.
48:05And briefly, some very premature results.
48:09When we try to associate the increase on mortality,
48:13on daily mortality
48:14attributed to this very intense heat wave,
48:17this accounted for about 20% increase.
48:21This is a huge increase.
48:22If we consider, for example, that high temperature levels
48:28account for about four to 5% increase in daily mortality,
48:3320% increase in daily mortality due to a heat wave
48:36is a very severe public health issue.
48:40And this even reached 70% increase in daily mortality
48:44when this intense heat wave
48:46was combined with a wildfire that lasted about a week
48:51in the outskirts of the city.
48:54So to conclude, and thank you for your attention,
48:58there seems to be synergistic and interactive effects
49:01between climate change variables,
49:03such as temperature and air pollution.
49:06There is heterogeneity on the effects,
49:08depending on the location we are studying,
49:11but this may be also attributed
49:13to a large variety of factors, also socioeconomic factors,
49:17the percent of aging of the population,
49:21and other demographic characteristics.
49:24There is a call for further research interactions
49:27between parameters of air pollution
49:29and climate change events,
49:31but also on the assessment of the cumulative effects
49:34of all these environmental factors.
49:38And there's also a need
49:39to address more complex future scenarios,
49:42accounting for reduction on tailpipe emissions
49:46due to the electrification of the fleet,
49:50as I mentioned earlier.
49:52But this is also expected to account for an increase
49:55in non tailpipe emissions, due to tire wear and brake wear.
50:01And we need to push through policy decisions
50:06to develop solutions that will effectively tackle
50:09both climate change and air pollution levels,
50:13because these seem to be
50:19undividedly interchanged between them.
50:22So thank you very much for your attention,
50:25and I would particularly like to thank my team
50:28in the University of Athens,
50:29and also the consortium of the EXHAUSTION research program
50:34at (indistinct) in Europe.
50:36And I will be happy to discuss any questions,
50:39either today, or in person in about two weeks time.
50:46<v Professor Chen>Thank you.</v>