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

November 15, 2022

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

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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>