Asthma and Air Pollution Health Effects Workshop July 29, 2008 NESCAUM David R. Brown ScD

To day we will Define asthma Define the environmental problem Basic Mechanisms Contribution of Air pollution to asthma Pollutants linked to asthma Pollutants linked to attacks Regulatory requirements

Asthma and Airways

Asthma physiology Chronic disease that affects airways. The inside walls of airways are inflamed (swollen). Inflammation makes the airways sensitive Airways react strongly to things that are allergic or irritating. Airways get narrower, and less air flows to lung tissue.

Symptoms of asthma Wheezing (a whistling sound when you breathe), Coughing, Chest tightness, Trouble breathing, especially at night and in the early morning. Life threatening respiratory distress

During an asthma attack Muscles around the airways tighten up, Making the airways narrower Less air flows through the airway Inflammation increases, Airways become more swollen and narrower. Cells in the airways make more mucus The extra mucus narrows the airways. These changes make it harder to breathe.

What Causes Asthma? Inflamed airways may be due to a combination of things. When people in a family have asthma, children are more likely to develop it. Exposure to things like tobacco smoke, infections, and some allergens early in life may increase chances of developing asthma. Occupations,such as teaching, are associated with higher rates of asthma Relocation from rural areas to city increase asthma in progeny

Causes of attacks Biological Allergens –Animal dander (from the skin, hair, or feathers of animals) –Dust mites (contained in house dust) –Cockroaches –Pollen from trees and grass –Mold (indoor and outdoor)

Causes of attacks non-b iological Irritants –Cigarette smoke –Air pollution –Cold air or changes in weather –Strong odors from painting or cooking –Scented products –Strong emotional expression (including crying or laughing hard) and stress

Who Is At Risk for Asthma? Asthma is closely linked to allergies but not all, people with asthma have allergies. Children with a family history of allergy and asthma are more likely to have asthma. About 20 million people in US have been diagnosed with asthma;9 million are children. Asthma affects starts in childhood. More boys have asthma than girls, but more adult women than men. African Americans are more likely to be hospitalized for asthma attacks and to die from asthma

Asthma, Traffic and Air Pollution Diesel emissions: In traffic-choked New York City, children were twice as likely to be hospitalized for asthma as the average American child. Factors like dirty air can trigger an attack. Cutting traffic congestion and air pollution is an option

The connection between asthma and dirty air Smog and soot trigger attacks. There is evidence that ozone in smog and diesel exhaust particles may even cause asthma. Other triggers –nitrogen oxides, –formaldehyde –environmental tobacco smoke, –other toxic air contaminants like pesticides are suspected of contributing to asthma attacks but have not been conclusively proven to do so. Two-thirds of asthmatics live where at least one federal air- quality standard is not being met.

Factoids about Asthma # 1 Atlanta during the 1996 Summer Olympics. To reduce traffic congestion, the city enhanced public transit, closed downtown to private cars Daily peak ozone levels dropped 28% and hospitalizations for asthma fell by almost 20% The Atlanta case demonstrates a link between air quality and the prevalence of asthma attacks,

Factoids about Asthma # 2

Factoids about Asthma # 3

Factoids about Asthma # 4

Factoids about Asthma # 5 If a person moves from rural to city asthma rates increase in the next generation –ASIA –New Zealand –Soviet Union –South and Central America

What about patterns of exposure? Ozone Particulate Matter Nitrogen Dioxide Sulfur Dioxide Hazardous Air Pollutants (Toxins) Lead Carbon Monoxide

DIESEL PARTICLE PM 2.5 RANGE WATER ADSORBED IRRITANT GAS ABSORBED IN WATER Irritant gases Deep lung exposure to irritants How particles increase exposure of irritants to the deep lungs

Results from the Harvard Six-cities study: All Cause Mortality Rates most exposed to least exposed City Fine Particles All cause death 1.26 ( ) Lung Cancer 1.37 ( ) Cardio pulmonary 1.37 ( ) Other causes 1.01 ( ) Range of exposure ug/m3 Dockery, NEJM 1993; 329:

Health actions from exposures of 2 hours or less. Peters etal. pm 2.5 & myocardial infarction –1.48 odds ratio 2 hr after 25ug/m3 increase –1.69 odds ratio 1 day after 20ug/m3 increase Gent etal. Severe asthma & O3, pm 2.5 –35% increase wheeze 1 hr after 50ppb O 3 inc. –47% increase in chest tightness 1 hr after. –1.24 odds ratio Chest tightness 12-18ug/m3 pm

If attacks occur less than 2 hours after exposures Can daily averages prevent peak exposures? Can regional averaging show areas and times of risk? Will staying indoors prevent an exposure?

As part of the process to determine whether an area meets the EPA particulate matter standard, this 3-month long series of hourly observations would be collapsed to a single value… 9.2 ug/m 3 … Totally obscuring any “structure” or other “content” within the data set (Carmine Dibattista, CT DEP).

PM 2.5 New Haven, Hartford and Waterbury (ug/m3)

Compare Bus to School and Ambient monitor for PM.

Difference in amount of exposure between times of day

Actual inhaled dose varies between day, time of day, activity and location

One half the volume in each hour One half the volume out each hour School Buildings have memories of outside exposures A 400 ppm diesel particulate emission from a bus that idles for one hour next to the school exposes the students for over 3 hours

Possible diurnal influence on school air

Analyzing fine PM data by comparing 3-hr exposure distributions to daily and annual averages reveals significant underestimation of potential health risk. Comparison of PM hr avg and 3-hr max avg for New Haven CT site, 2001

Local air quality events that are seen inside the school Buses idling Morning traffic Commercial vehicles Construction Sun rising and sun setting Nocturnal Jet Sun rising and sun setting Changes in the weather Pesticide applications

If attacks occur less than 2 hours after exposures Can daily averages prevent peak exposures? No Can regional averaging show areas and times of risk? No Will staying indoors prevent an exposure? No

Separate regulatory compliance from health risk A shorter averaging time is needed. –2 hours to 6 hours Measures should be based on aggregate dose. Which should be the health based standard (HBS) Number of days when the HBS is not met should be the criteria to measure trends

Finally if particulate and irritant exposure interact Can measures of single pollutants explain the public health risk? No, but approaches that attempt in integrate rather than reduce the variability will. Thank you very much.

“ Bad” Air Quality Ozone Particulate Matter Nitrogen Dioxide Sulfur Dioxide Hazardous Air Pollutants (Toxins) Lead Carbon Monoxide