EnvironmentalHealth Perspectives Vol. 79, pp. 179-185, 1989



# Acute Lung Function Responses to 

# Ambient Acid 

# Aerosol Exposures 

# in Children
by Mark E. 

# Raizenne,* Richard 

# T. Burnett,* Bonnie 

# Stern,* 

# Claire A. 

# Franklin,* and John D. 

# Spenglert

We examined the relationship between lungfunction changes and ambient acid aerosol episodes in children attendinga residential summer camp. Youngfemales (112) performed daily spirometry, and 96 were assessed on one occasion for airway hyperresponsiveness using a methacholine bronchoprovocation test. Air qualitymeasurements were performed on site and four distinct acid aerosol episodes were observed during the 41-day study. The maximum values observed during the 41-day studywere: 03 at 143 ppb; H2SO4 at 47.7 ,ug/m3; and [H+i at 550 nmole/m3. Maximum decrements of 3.5 and 7% for FEV1 and PEF, respectively, were observed to be associated with the airpollution episodes. There was some evidence of a differential lung function response to the episodes where children with a positive response to a methacholine challenge had larger decrements compared to theirnonresponsive counterparts.


## Introduction

Ambient acid 

### aerosols 

### resulting from 

### atmospheric transformations of 

### primary pollutants may represent

a 

### significant health hazard 

### (1). Acid aerosols are often observed to be associated with other air

### pollutants in

### cluding ozone 

### (03), nitrogen oxides 

### (NOx), and sulfur dioxide 

### (SO2) (2). There have been few

### epidemiological studies that have 

### specifically addressed the acidic 

### aerosol-health effect 

### hypothesis. Although no one 

### studyhas 

### clearlyassociatedacidaerosolswithobserved adverse health responses, there is 

### mounting evidence from 

### both 

### toxicological and clinical 

### studies that suggest that 

### moderate exposures to 

### air

### pollution mixtures

can influence 

### respiratory health and function 

### (2). Air

### pollutionepisodes havebeen

### observed to

### be associated with acute 

### mortality and acute and chronic 

### respiratory morbidity 

### (3). Evidence that acute 

### respiratory health and function in children is affected 

### by ambient air 

### pollutants at or near current air 

### quality standards has been 

### reported by several 

### investigators 

### (4-11). Although the 

### biological evidence for these associations resides 

### principally in transient decrements of 

### lung 

### function, the 

### implications of 

### repeated

*Department of National Health and Welfare, Health Protection Branch, Ottawa, CanadaKiA0L2. tHarvard School of Public Health, Boston, MA02115. 

### exposures and 

### subsequent decrements on 

### human res

### piratoryhealth remain to 

### be 

### determined. It is not 

### clear at 

### the present time 

### whether these 

### changes have causal 

### consequences in 

### the 

### development or

### promotion of

### lung disease. Summer 

### camps have been 

### used 

### by several investi

### gators to assess 

### the influence of 

### ambient air 

### pollution
on 

### respiratory health 

### and function of 

### children. Be
### cause 

### children are 

### predominantly outdoors and 

### rela

### tively active 

### while at 

### camp, 

### they 

### provide a 

### unique opportunity to assess 

### the 

### relationships between res

### piratory health and function and concurrent air 

### pollution levels. Raizenne 

### et al. (10) have 

### reported shortterm 

### decrements in 

### the 

### lung function 

### of 

### children at

### tending a 

### residential summer 

### camp in a 

### region re

### ceiving a mixture 

### of air 

### pollution, 

### including acid 

### aerosols. 

### Lung function decrements were 

### associated with 

### 03, fine 

### particles (PM2.5), 

### sulfates, and 

### temperature. 

### Thesedecrementswere

### also 

### observedto

### beassoci

### ated with 12- 

### and 24-hr time 

### lags. Other 

### investigators 

### (7,8,11) have 

### also 

### reported observing decrements in 

### lung function in 

### children at 

### camps to 

### be 

### related to 

### ambient air 

### pollution levels. In one 

### study (7), the 

### decrements were most 

### strongly associated with 

### 03 and
were 

### reported to 

### persist for 

### up to 1 

### week after a 

### 4-day 

### pollution episode having a mixture of 

### pollutants in

### cluding acid 

### aerosols. Other recent 

### studies indicate that 

### persistent lung function decrements are 

### observed in 

### children after an air 

### pollution 

### episode where 

### S02RAIZENNE ETAL.



### and total 

### suspended particulates 

### exceeded 200 

## gg/m3 (12,13). 

### The 

### present study was undertaken to 

### examine the 

### relationship between acute exposure to 

### ambient pollutants including 03, fine 

### particles (PM2.5), sulfates, and 

### sulfuric acid 

### (H2SO4) and respiratory function in 

### children. 

## Methodology

A 

### residential Girl Guide camp 

### located on the 

### north shore of Lake 

### Erie, 50 km 

### southwest of Hamilton, Ontario, was 

### used in this study. 

### There were three 

### con

### secutive 2-weeksessionsbetweenJune 29 

### andAugust9, 1986. 

### One hundred forty-five 

### young girls between 

### the 

### ages of 8 

### and 14 

### were 

### contacted, and 

### 116 agreed to 

### participate in 

### the 

### study

### activities. Parentswere asked to 

### complete a 

### self-administered questionnaire on 

### the 

### child's 

### respiratory health history, parental health, and 

### household characteristics. 

### Spirometry was 

### performed each 

### day in 

### two 

### mobile trailers 

### located on 

### the 

### camp site. Four 21E 

### Pulmonary Function Workstations 

### (Gould Medical Products, Dayton, OH) were operated by 

### four experienced technicians. 

### The method of 

### testing 

### followed the

### ATS (14) and GAP 

### (15) 

### spirometry guidelines for testing of 

### children and 

### incorporated a minim'um 

### of five 

### maneuvers 

### (16). Childrenwere

### testedeachday

### between3:00 

### P.M. and

### 5:30

### P.M., ina

### seatedpositionand

### with

### noseclips in

### place. 

### Children came 

### tothe testsiteat

### approximately the 

### same 

### time 

### each day 

### (± 30 

### min). Spirometers 

### were calibrated each 

### day before testing and 

### whenever 

### the ambient temperature 

### changed by 20C 

### during the 

### testing session. 

### Calibration was' 

### performed 

### by" each 

### technician using a 3-L 

### syringe. All 

### lung measurementswere 

### correctedto

### BTPS 

### (bodytemperatur'e, pressure, 

### saturated) values. 

### Height and 

### weight-were mea

### sured at 

### each of 

### the first four 

### lung function tests, and 

### the mean of

### the fourmeasurements was 

### used to 

### define
a

### unique 

### height andweight for 

### each 

### child.' Methacholine bronchial 

### challenge 

### (MCh) tests were 

### performed on 

### the third or

### fourth 

### day of

### each session 

### at 

### the 

### camp site. All 

### parental 

### questionnaires'* were reviewed 

### by attending 

### physicians at 

### the site prior to 

### the test. 

### Children with a

### history or current 

### symptoms, i.e.,persistent

### wheeze, 

### asthma, 

### allergy, andrecent

### colds,
were 

### scheduled 

### early in 

### the 

### day to 

### monitor 

### possible latentresponses. 

### All testswere

### conductedbetween 

### 8:30 A.M. 

### and 5:00 

### P.M. The method of

### Hargreave et-

### al. 

### '(17)
was 

### used for 

### all bronchial 

### challenges. The maximum concentration 

### used was 16 

### mg/mL and the'maximal response for termination of 

### the test was a 20% 

### decrement in 

### FEV1. The concentrations of 

### methacholine 

### inducing a 20% decrement in 

### FEV1 (PC20FEV1) were 

### obtained, andpositivemethacholine tests (MCh+) were defined as 

### children having a 

### PC20FEV1 of 8 

### mg/mLorless. All spirometric 

### assessments associated with the 

### methacholine challenge were 

### performed on two 8-L 

### Collins (Braintree, MA) 

### water-filled spirometers, calibrated eachdayusinga 3-Lsyringe. To 

### determine 

### atopy, skin 

### tests were 

### performed 

### using theprickmethod. Tencommon

### allergens 

### (Table 1) were 

### used, along with 

### negative 

### (diluent) and 

### positive (histamine, 8 

### mg/mL) controls. Wheal 

### diameter was 

### measured by ruler 

### and 

### caliper and 

### recorded to the 

### nearest 1 mm. A

### wheal diameter 2 

### mm or more 

### larger than the 

### response to 

### diluentwas 

### regarded as a

### positive test An air 

### pollution monitoring station was 

### operated on-site in a van 

### situated in an 

### open area 

### approxi

### mately 10 m 

### from the 

### lung testing trailers. The air 

### pollution trailer housed 

### continuously recording 03, SO2, NO2 monitors, and a thermal speciation 

### flame photometric unit 

### (modified 

### Meloy 285) 

### (18), which measured 

### continuously total 

### sulfate 

### (CSO42-) and

### H2SO4 

### (da

. 2.5 

### gm). Ambient air 

### samples for 

### the 

### continuous monitors were made 

### through a 

### Teflon and 

### glass filter mounted from an inlet 

### situated on 

### the roof of 

### the trailer 

### approximately 5 m from 

### the 

### ground. Ten

### minute and 

### hourly averages were obtained from 

### the continuous monitors. Two 

### Beckman dichotomous 

### particle samplers located on the roof of the 

### trailer sampledfine 

### (da



### . 2.5

### gim) andcoarse 

### (2.5 <

### da

. 10

### gm) particle mass 

### sulfate and elements 

### using teflon 

### filters. 

### Aerosol strong 

### acidity ([H+] nmole/m3) and 

### particle sulfate 

## (SO2-) were 

### determined from fine 

### particle mass 

### collected 

### by a 

### Harvard 

### impactor using Teflon 

### filters with ammonia denuders (19). Organic and elemental 

### carbon were 

### measured with a second 

### Harvard impactor using 

### prefixed quartz filters. Two 12-hr 

### samples perday 

### (starting 7A.M. 

### and 7 P.M. 

### EST) were 

### collected from 

### each particle monitor. 

### Meteorology pa

### rameters, temperature, dewpoint, andwind 

### speed and 

### direction were 

### monitored 

### continuously with an 

### hourly averaging point time 

### using a 

### Climatronics modular WM-111 

### system. Table 2 summarizes 

### the 

### aerometric measurements 

### and the 

### exposure metric 

### definitions. The 

### percent data 

### capture 

### during the 41- 

### -dayperiod

### equaledor

### exceeded 95%for

### all

### parameters. The influence 

### of air 

### pollution 

### episodes on 

### the 

### lung function of 

### children was 

### examined 

### by determining 

### the difference in 

### lung function for each 

### child between 

### days of 

### high and 

### low 

### pollution. Four 

### distinct intervals of 

### elevated air 

### pollution and the 

### corresponding control 

### days are 

### identified in

### Table 3. 

### Control 

### days
were defined as 

### days with 

### 03 max < 80 

### ppb; 

### SO2- < 15

Table 1. Skinpricktest: Allergens.
Alternaria tenuis Aspergillusf'umigatus Cathair/epithelium Doghair/dandermix Dustmite (Dermatophagoides farinae) Grasspollen Hormodendrumcladosporiodes Horsehair/dander Ragweedpollen Treepollen 180ACUTE LUNG FUNCTIONRESPONSES TOACIDAEROSOL EXPOSURE

Table 2. Pollutant exposuremetrics.
Pollutant, units Method 03, ppb Chemilumninescence

1 hrmaximumismaximumhourly value for 12-hrperiod, 7A.M.-7 P.M.
PM 2.5, Ag/m3 Dichotomous sampler

12-hr integrated sample (mass), 7A.M.-7 P.M. SO4, Ag/m3 Harvard impactor (withdenuderinlet) [H+], nmole/m3 12-hrintegrated sample, 7A.M.-7 P.M.

Total sulfate andaerosol strongacidity H2SO4, Ag/m3 ModifiedMeloy 285 [Allen et al. (18)]

Flamephotometry Continuous (10min/1-hr averages) Temperature, OC Mean ofhourlymeasurements over

12-hrperiod, 7A.M.-7 P.M. Relativehumidity, % Average % relativehumidity over

12-hr samplingperiod, 7A.M.-7 P.M.

,ug/m3; 

### H2SO4 < 10 

### gg/m3 (or [H+] < 55 

### nmole/m3). Note that there were two episodes identified in session 2. Thedifferencebetween the lungfunction response on the episode dayandthe average ofthe responses onthe corresponding control days was determined for each child and each of the responses separately. The distribution of these differences across children was examined. The mean ofthe differences were then tested to differ from zero by a one-sided t-test. A similar procedure was performed separately by methacholine

response.


## Results Subject characteristics are presented by session in Table 4. A total of 112 children (77.2% of contacted) participated in the study. Of those initially contacted, 20% refused to participate, one never attended, two left

camp early, and one subject withdrew from the study. Five children were reported to have doctor-diagnosed current asthma (from parental questionnaire), five did not perform the methacholine and allergy test, and six children did not perform either the methacholine

or the allergy test. Excluding the five asthmatics, a cohort of 96 children had complete data on all health components. For the 107 nonasthmatic girls with daily lung function results, a summary of the daily lung function responses is presented in Figure 1, where the

average residual value from each child's own mean

across days isdisplayed foreachday (± 2 SE). Foreach session, the meanvalues for FVC, FEV1, and 

### FEF25-75 exhibit a U-shaped pattern over time in which the

average on the first day was larger than the otherdays. A rapid decrease in function was observed initially, with a subsequent more gradual recovery. This pattern

was not observed for peak expiratory flow (PEF), and there was evidence of increasing values in the daily

means in the latterportion ofthe third session. Methacholine bronchial challenge (MCh) was successfully completed by all subjects in the cohort of 96 children. Thirty-nine children (40.6%) had a positive

response (MCh+). Atopy to one or more of the 10 inhalant allergens noted was observed in 47 of 96 children, or 49% of the cohort. Twenty-one of 96 children (21.8%) had both positive methacholine and a positive atopyassessment. The influence of MCh+ on lung function parameters (FVC, FEV1, and PEF) was examined (Table 5). It was observed that children with MCh+ tests had smaller

mean values for all three lung function parameters after adjusting for age and height. The effect of atopy

was observed to have no significant influence on lung function. Air pollution during the study period displayed day-to-day and diurnal variation. During each of the 2-week camp periods, four distinct pollution events

were observed. During these events, maximum 1-hr

03 concentrations exceeded 100 ppb; 12-hr [H+] ion concentrations exceeded 100 nmole/m3. More than half of the particle mass during these events were sulfates. The ambient levels ofNO2 and SO2 were low, with the maximum 12-hr concentrations of these gases being 10 ppb, and no single hour exceeding 25 ppb. These reflect the remoteness of the camp from local stationary and mobile sources. The most intense airpollution eventbegan to develop in the late morning of July 24, when 03 and cSO2- 

### c4
concentrations increased sharply. After dropping

Table 3. Pollutionepisode andcorrespondingcontrol days.
Episode Type of Pollutionlevelsa Session number day Date 03 max, ppb [H+], nmole/m3 SO

,,gm 1 I Control' June 29-July3 78 32 9

Episode July 6 128 321 49 2 II (a) Control' July 13-16 79 49 8 Episode July 18 133 100 14 2 II (b) Control' July 13-16 79 49 8 Episode July25 143 559 83 3 III Controlb July27-31 79 53 14 Episode August 6 108 306 54 

### a03 max, fromhighesthourlyvalue 12-hourdata set; [H ] and

### SO4'- fromHarvardimpactordata set. 

### bMaximumvalue across all control days. 181RAIZENNE ETAL.

Table 4. Sample size and cohort characteristics by session.
Session Characteristic I II III Mean

n = 112 53 32 27 Age, yearsa 11.6 11.5 11.7 11.6 Height, cma 151 146.2 148 149 Weight, kga 44 41 43 43 

### aMeanvalues. 

### slightly overnight, the levels 

### increased again on July 25, 

### reaching a maximum between noon 

### and 1:00 P.M. 03 

### concentrations were 143 ppm, 

### particle sulfates 

## (CS02-) exceeded 100 

## gg/m3 with 

### approximately half 

### (47.7 

### ,ug/m3) in 

### the form of 

### H2SO4 

### (Meloy 285 

### data). During 

### the most intense portion of the 

### episode, H+ ion concentrations 

### averaged 550 

### nmole/m3. The 

### correlations between 

### daytime 

### (12-hr) 

### pollutants
are 

### presented in

### Table 6, 

### and indicate a

### high degree of 

### correlation between PM2.5, 

### S02- and H+; 

### however,

0o100

0 050 FVC (L) 0

-0-050

-0-100

0I100

0 050

0

- 0-050

- 0100

0-4

0-2

0

-0-2

-0-4

0.20

0O10

0

-0o10

-0 20 Is

T I1 Table 5. Height andage-adjustedmeanpulmonary function responses bymethacholine responsiveness.

Methacholine Function MCh- pa MCh+ Mean FVC, L 2.66 0.029 2.54 2.62 FEVI, L 2.36 0.003 2.21 2.30 PEF, L/sec 5.61 0.001 5.18 5.43

n 57 39 96 

### aTwo-sidedp-valuefortesting

### differencebetweenMCh

-

### and.MQh+.

Table 6. Pearson correlation coefficients for daytime (12-hr) aerometric data.
Relative SO4- [H+1 03 max Temperature humidity
PM 2.5 0.97 0.95 0.78 0.32 0.37 SO4- 0.96 0.82 0.30 0.36 [H+1 0.80 0.37 0.29 03 max 0.48 0.52 Temperature 0.30



### temperature 

### and relative humidity were 

### weakly correlated with 

### the air 

### pollutants and each other. Nighttime correlations were 

### observed to 

### be 

### marginally 

### reduced compared to 

### daytime values. Daytime 

### values
are 

### graphically presented in 

### Figure 2. More 

### details on 

### the monitoring 

### data can 

### be obtained from 

### Spengler et 

### al. 

### (20). The influence of air 

### pollution on 

### lung function was 

### examined 

### by comparing children's responses on 

### the 

### day of a major 

### pollution 

### episode to the mean of 

### the responses on 

### corresponding days of low air 

### pollution, 

### termed control 

### days. Table 7 

### gives the average 

### change in lung function 

### between the 

### episode and the 

### control 

### days for 

### children with 

### positive and 

### negative methacholine responses. A

### furtherresponse, 

### II(c), was

### defined relating to 

### episode II(b) in

### Table 6 

### and is given 

### by the difference between the 

### lung function responses 

### taken the 

### morning after 

### episode II(b) and the average of the 

### control 

### days used for 

### II(a) and 

### 11(b). For 

### FEV1, there
was a tendency for the lung function responses on the 

### dayof

### the 

### episodes to

### be less than the responses on 

### the 

### correspondingcontrol

### days except forthe

### episode in

### the 

### third session, in 

### which an increase in function was 

### observed. The 

### children with 

### positive methacholine responsiveness were 

### observed to 

### have 

### larger decrements in 

### function 

### during the 

### episodes than their nonresponsive counterparts 

### (Table 7). A 

### similar patternwas 

### observedfor PEF 

### (67-143 

### mL/sec decline). For 

### both responses 

### (FEV1 and 

### PEF) the 

### largest decrements were 

### observed on 

### the 

### morning after 

### the 

### July 25 

### episode in session 2 

### where 

### FEV1 declines of 80 

### mL, and PEF

### declinesof383

### mL/secwere

### observed.

29 3 7 JUN JUL II 15 19 23 27 31 4 8 AUG

DATE (1986) Fi(;tJRE 1. Standardized lung function measurements bydate. I (+)/(-), standard errors. 

## Discussion

To date, most health studies have reported ambient acid concentrations, primarily H2S04, to be in the

range of 2 to 10 ,ug/m3 using the continuous flame FEV1.0 (L)

PEF 

### (Usec)

FEF25 75 

### (Usec) 182

IACUTE LUNG FUNCTIONRESPONSES TOACIDAEROSOL EXPOSURE

occasion 

### and to 

### exceed 20

## gg/m3 forH2SO4 onat least two 

### other occasions 

### during the 41-day summer 

### period. The initial analyses of the effect of episodes on acute pulmonary function indicate that only 

### small changes in 

### pulmonary function may be 

### observed to occur 

### with 

### episodes of air 

### pollution having high concentrations of

### acid 

### aerosols. Although the 

### magnitude and 

### temporal characteristicsof

### these changesaremodest, theyappear consistent 

### with other studies where acute 

### and/or per- 

### *BeforeandAfter sistent declines in lung function are associated 

### with DataMissing specific airpollutants. The studyalso demonstrates that

frequent and prolonged 

### episodes of relatively high concentrations of

### acid aerosols do occur in 

### the summer 

### period in 

### Southwestern Ontario.

R.H. 7U

- \| l

(0/0) 60

50

29 2 5 8 11 14 17 20 23 26 29 4 7 JUN JUL AUG

DATE (1986) Fi(t;Rvi 2. Environmental factorsbydate. photometric technique and/or equivalent units when the titratable acid method is used (H+, nmole/m3). In the present study, continuous ambient acid measurements were observed to attain 47.7 tg/m3 on one Lung function measurements 

### throughout the three camp sessionswere remarkably stable for

### all indices. In 

### all three sessions, the first measurement was signifi

### cantlylargerthan the mean of

### the last nine tests. 

### There
was evidence that larger, 

### older children 

### produced ac

### ceptabledatamore 

### frequentlyon

### the first

### day. However, when we examined the 

### childrenwith complete data on 

### all 

### days, the difference on the first 

### day remained significant. 

### This suggests 

### that for 

### this 

### study, the first measurement may not be a 

### reproducible value and may not 

### be a 

### representative value of 

### baseline 

### lung function. 

### There is 

### also evidence of a pattern in 

### lung performance, in 

### all 

### three sessions, where the initial 

### values for FVC, FEV1, 

### and 

### FEF25-75 are 

### high, decrease for a few 

### days, and then increase 

### and 

### stabilize for 

### the rest of

### the session. 

### The pattern

### differed for PEF, 

### where the measurements 

### appeared stable in 

### the first two sessions 

### but 

### deviated in session 3, 

### when it 

### appeared to 

### progressively increase 

### with time. 

### The third session 

### data are 

### discussed later. There appears to exist a

### dayof camp effect 

### where similar trends in 

### lung measurements 

### by day occur across 

### the three 

### independent sessions. 

### The reason for 

### this trending is not 

### evident, and the influence of 

### this trend will be 

### examined in future 

### analyses.

Table 7. ChangeinFEV, andPEFbetweenepisodeandcontroldays

bymethacholine responsiveness.
FEVI, mL PEF, mL/sec MCh- MCh+ MCh- MCh+ Episode (n = 57) (n = 39) (n = 57) (n = 39)
I -34 -48 -79 -67 (July6) (0.008)a (0.041) (0.113) (0.228)
II (a) -49 -59 30 -135 (July 18) (0.022) (0.170) (NA) (0.189)
II (b) 3 -66 -57 -143 (July25) (NA)b (0.144) (0.270) (0.218)
II (c)c 5 -80 -91 -383 (July26) (NA) (0.142) (0.191) (0.039)
III 10 39 109 211 (Aug. 6) (NA) (NA) (NA) (NA) aOne-sidedp-valuefromonesamplet-testtotestifchangeisnegative. bNA, p-value notappropriate, since change ispositive. 

### CDffferenceinlungfunctionvaluebetweenday

### afterepisodeII(b)and control days. 500

400

300

200

100

0

80

60

-

40 e [H+] (nmoles/m3)



### s04g (jAg/r3)

20

0

PM2.5 (Ag/M3) 140

120
100
80
60
40
20 0 V

I I-"/",OI
rH ,6

.



# *. <

Il Il

r-i I~~~~~~~~~~~~~~~j 140

120 03 100 max (ppb) 80

60

40

78

74 Temp. 

## (oF) 70

66

62 183

-1 

## -rw/,184 RAIZENNE ETAL.



### The influence of a 4-day episode when 03 concen

### trationsexceeded 150ppbhasbeen

### reportedto

### havebeen 

### associated with decrements in PEF 

### measurements and thatthis decrementpersistedfora

### period of 5 to 7 

### days in children attending a summer camp (7). Persistent decrements in various lung function indices have 

### also been associated with 

### episodes of total 

### suspended particulates and 

### SO2 (12,13). Although the design of these latter studies differed markedly from those of Lioy et al. (7) and from the current study, they all demonstrated a 

### persistent decrement in 

### lung function 

### following an air 

### pollution event. This 

### type of 

### response may account for 

### the low PEF 

### values and the subsequent increase, or 

### recovery, noted in 

### the 

### third session. 

### The PEF data for the third camp were unexpected 

### results. The measurements of PEF in 

### the first fewdays of

### session 3maynothavebeenrepresentativevalues, as 

### the children 

### came from the Hamilton 

### area, and 

### they would have been exposed to the polluted airmass that affectedthe region. There is evidence 

### thatthisairmass 

### extended as far as 

### Toronto (21), and Hamilton is situated betweenToronto and the 

### camp site. 

### Furthermore, Hamilton is known to have significant local sources of air 

### pollution (22), and the 

### pollution profile in 

### the Hamilton region during the event may have been
more intense. In

### this 

### study, we 

### observedthat PEF

### was

### decreased on 

### the dayof, and on 

### the morning

### following, the session 2 

### episode. If 

### we assume a 

### similar response in 

### children originating from 

### Hamilton, and assume a 

### persistent decline to 

### be 

### present when the 

### children arrive for 

### the 

### third session, then the initial PEF 

### data for 

### the third 

### session 

### maybe evidence ofa

### persistent decrement and 

### subsequentrecoveryfrom

### the

### episodethatoccurred 5 to 7 

### days previous to 

### the 

### positive 

### trending in 

### the PEF 

### values in the last session. As 

### shown in 

### Figure 2, the 

### pollution profile indicates that 

### 03 was near

### the 150

### ppb level 

### (143 

### ppb) and that 

### high aerosol 

### acidity was 

### also 

### present during the 

### July 25 event. 

### Although the association 

### between 

### decrements in PEF 

### and 

### 03 is 

### significant in

### the 

### Lioyet

### al. 

### study, the authors note 

### that other 

### pollutants, including acid 

### aerosols, may have con

### tributedto

### the

### persistentdeclineobserved. 

### Chamber studies have 

### provided evidence that adolescent 

### children, particularly asthmatic 

### children, may be 

### especially sensitive to 

### levels of 

### air

### pollution periodically observed in various 

### ambient 

### settings. Avol et 

### al. 

### (4) exposed children to 

### ambient oxidant air 

### pollution and 

### reported significant decrements in 

### lung function. 

### Koenigetal. 

### (23) have

### reportedevidence of

### decrements in 

### lung function of

### young asthmatics when 

### exposed to 

### H2SO4 aerosols at 100 

### ,ug/m3. Further 

### preliminary evidence 

### by the same 

### author was 

### presented at 

### this 

### symposium, which indicate altered 

### lung mechanics at 

### concentrations of

### H2SO4 of68 

### ,ug/m3 (24). Chamber studies have 

### also demonstrated enhanced 

### pulmonary mechanical 

### responses to 

### SO2 and 

### 03 when exposures are 

### coupled to 

### controlled exercise 

### regimes 

### (21). Utell 

### (25) notes 

### that exercise 

### potentiates 

### pulmonaryresponses to 

### H2SO4 pollutants, particularly in 

### asthmatics. Planned activities during the camp did not include events that required vigorous activity and exertion. The absence of regular, vigorous activity events may have been a significant factor mediating the daily, and episode, lung function responses of the 

### children. Atthepeakof

### theJuly 25 

### episode, 12 

### subjects performed pre- and postexercise spirometry (26). For 

### thegroup, postexercise FVC andFEV1wereobservedto 

### increase on control day tests and to decrease on the episode day. The magnitude of this difference, how

### ever, was not observed to be statistically different. The expected direction and magnitude of changes in lung function after an air 

### pollution episode appear con

### sistent with evidence of changes in 

### lung function in 

### highly controlled chamber exposure studies to various air 

### pollutants. Airway hyperresponsiveness is a common characteristic of 

### asthma. However, 

### there is evidence of non

### specific airway 

### hyperresponsiveness being present in 

### nonasthmatic, asymptomatic populations (27). In addition, recent evidence has suggested that nonspecific bronchial 

### responsiveness may reflect a 

### predisposition 

### to 

### the development of chronic 

### obstructive lung disease (28). We 

### observed that 40% of our nonasth

### matic children had MCh+ tests and that 33% of these children had no histories of chronic respiratory symptoms. We also noted that lung function changes due to 

### the 

### episodes in 

### the MCh+ 

### group, in 

### the first two 

### sessions, were 

### consistently negative 

### and, in 

### general, larger than the decrements in the MCh- 

### group. In 

### Table 7, 8 of 10 lung function responses in 

### the MCh+ 

### group are 

### negative, while 5 of 10 are 

### negative in 

### the MCh- 

### group. We further note that after 

### adjusting for 

### age and height, MCh+ 

### children had 

### lower 

### lung function and 

### greater 

### day-to-day variability 

### (data not 

### given) in 

### all 

### lung function 

### indices when 

### compared to 

### the MCh- group. These 

### preliminary results do not 

### permit definitive statements on 

### the 

### susceptibility of 

### methacholine sensitive 

### subjects to 

### be 

### made; however, there are 

### indications in 

### these data of 

### differential lung function 

### profiles and 

### responses to air 

### pollutants in 

### children with and 

### without airway 

### hyperresponsiveness. 

### Further analyses are 

### currently directed in 

### examining these differences and their 

### relationships with air pollution.

We thank the children attending Camp Kiawa, their parents, the Camp Kiawa staff, and the Hamilton Girl Guide Council for their cooperation throughout the study. Special acknowledgment is extended to Drs. M. Sears and E Hargreave and their co-workers at St. Joseph Hospital in Hamilton; the health field staff, J. Mortimer, C. Jette, T. Vlad, S. Dent; the aerometrics field staff, U. Allen, M. Wolfson, P. Koutrakis, T. Dhmyagn; our data analysis statistical associates, J. KearneyandD. Haines; andto E Marierforherassistance inpreparing themanuscript.

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